Download Neet PG Biochemistry MCQs Question Bank
2.Boiledcabbageorrancidbutter smellingurineisseenin a)Phenylketonuria b)Tyrosinemia c)IsovalericAcidaemia d)Multiplecarboxylasedeficiency CorrectAnswer-BTyrosinemiaREF:Sapira'sart&scienceofbedsidediagnosis-Page138,TextbookofPediatricEmergencyMedicinebyGaryR.Fleisher,StephenLudwigPage1566Tyrosinaemiaisanerrorofmetabolism,inherited,inwhichthebodycannoteffectivelybreakdowntheaminoacidtyrosine,foundinmostanimalandplantproteins.Itisanautosomalrecessive,whichmeanstwocopiesofanabnormalgenemustbepresentinorderforthistodevelop.Therearethreetypesoftyrosinemia,eachwithdistinctivesymptomsandcausedbythedeficiencyofadifferentenzyme.OneofthesymptomsofTyrodinaemiatype1isanodorlikecabbageorrancidbutter.
3.TrueaboutGproteincoupledreceptorsis: a)Gproteinsbindtohormonesonthecellsurface b)Allthethreesubunitsalpha,betaandgammashouldbindto eachotherforGproteintoact c)Gproteinsactasinhibitoryandexcitatorybecauseofdifference inalphasubunit d)GproteinisboundtoGTPinrestingstate CorrectAnswer-CGproteinsactasinhibitoryandexcitatorybecauseofdifferenceinalphasubunit[Ref:Harper26/ep458;LippincottBiochem3/ep93;Ganong22/ep41]G-proteincoupledreceptors(GPCR)arethelargestsuperfamilyofcellsurfacereceptors.Theytypicallyhavesevenhelicesthattraversethemembrane.Thesereceptorsareintegralmembraneproteinscharacterizedbyanextracellularligand-bindingregion,seventransmembranehelices,andanintracellulardomainthatinteractswithG-proteins.ThefunctionofGPCRistotransducesignalsthatinduceacellularresponsetotheenvironment.Mechanism:Theligandbindstoasiteontheextracellularportionofthereceptor.Bindingoftheligandtothereceptor*activatesaGproteinassociatedwiththecytoplasmicC-terminal.Thisinitiatestheproductionofa"secondmessenger".Themostcommonoftheseare*cyclicAMP,(cAMP)whichisproducedbyadenylylcyclasefromATPand*inositol1,4,5-trisphosphate(IP3)
Thesecondmessenger,inturn,initiatesaseriesofintracellulareventssuchas*phosphorylationandactivationofenzymes*releaseofCa2+intothecytosolfromstoreswithintheendoplasmicreticulumGproteinsGproteinsareso-calledbecausetheybindtheguaninenucleotidesGDPandGTP.Theyareheterotrimers(i.e.,madeofthreedifferentsubunits)Thethreesubunitsare:*Ga,whichcarriesthebindingsiteforthenucleotide.Atleast21differentkindsofGamoleculesarefoundinmammaliancells.*GP*GyHowTheyWorkIntheinactivestateGproteinhasGDPboundtoitsGa.subunit.WhenahormoneorotherligandbindstotheassociatedGPCRtheGDPisexchangedforGTPGTPactivatesGacausingittodissociatefromGI3Gy(whichremainlinkedasadimer).ActivatedGainturnactivatesaneffectormolecule(adenylylcyclase-anenzymeintheinner.sfaceoftheplasmamembranewhichcatalyzestheconversionofATPintothe"secondmessenger"cyclicAMP).Thebetaandgammasubunitdonotseparatefromeachother,andGi3Gydimeralsoactivatesavarietyofeffectors.TheactionsoftheGa-GTPcomplexareshortlivedbecausetheG-proteinhasaninherentGTPaseactivity,resultingintherapidhydrolysisofGTPtoGDP.ThisleadstoreassociationoftheGaunitwiththeGI3Gydimer.ThisinactivatestheGprotein.TheabilityofaligandtostimulateorinhibitthesecondmessengerdependsonthetypeofG-proteinthatislinkedtothereceptor.OnefamilyofG-proteins,designatedGs,isspecificforstimulationofadenylylcyclase;anotherfamily,designatedGi,causesinhibitionoftheenzyme.ThesedifferentactionsofGproteinsareattributedtodifferentalphasubunits.Gscontainsa,andGicontainsSomeTypesofGaSubunits
Gas_Thistypestimulates(s="stimulatory")adenylylcyclase.GasisthetargetofthetoxinliberatedbyVibriocholerae,thebacteriumthatcausescholera.BindingofcholeratoxintoGaskeepsitturned"on".TheresultingcontinuoushighlevelsofcAMPcausesamassivelossofsaltsfromthecellsoftheintestinalepithelium.Massiveamountsofwaterfollowbyosmosiscausingadiarrheathatcanbefatalifthesaltsandwaterarenotquicklyreplaced.Ga;-Thisinhibits(i="inhibitory")adenylylcyclaseloweringthelevelofcAMPinthecell.Gag_ThisactivatesphospholipaseC(PLC)whichgeneratesthesecondmessengers:*inositoltrisphosphate(IP3)*diacylglycerol(DAG)Gat_The"t"isfortransducin,themoleculeresponsibleforgeneratingasignalintherodsoftheretinainresponsetolight.
4.Respiratoryquotientofcarbohydrateis: a)0.5 b)0.8 c)0.75 d)1 CorrectAnswer-DAns:D.1Therespiratoryquotient(orRQorrespiratorycoefficient),isadimensionlessnumberusedincalculationsofbasalmetabolicrate(BMR)whenestimatedfromcarbondioxideproduction.Itiscalculatedfromtheratioofcarbondioxideproducedbythebodytooxygenconsumedbythebody.Suchmeasurements,likemeasurementsofoxygenuptake,areformsofindirectcalorimetry.Itismeasuredusingarespirometer.Therespiratoryquotient(RQ)istheratio:RQ=CO2eliminated/O2consumed
5.Essentialfattyacidsareexcept: a)Arachidonicacid b)Linoleicacid c)Palmiticacid d)Linolenicacid CorrectAnswer-ATheessentialfattyacidsarepolyunsaturatedfattyacids,linoleicacid(18:26)andlinolenicacid(18:33). Arachidonicacid(20:46)isderivedfromdietarylinoleicacidandispresentprimarilyinmembranephospholipids. Importantderivativesoflinolenicacidareeicosapentaenoicacid(20:63)anddocosahexaenoicacid(DHA,22:63)foundinhumanmilkandbrainlipids.Palmiticacidisacommonsaturatedfattyacid.Arachidonicacid(20C:ro6)isnotnutritionallyessentialbecausechainelongasesystemcanconvertlinoleicacid(l8C:<o6)intoArachidonicacid(20C:o6).Soarachidonicacidisconsideredasconditionallyessential,becauseithastobesuppliedinthedietiflinoleicacidisnotsupplemented.Ref:BothamK.M.,MayesP.A.(2011).Chapter23.BiosynthesisofFattyAcids&Eicosanoids.InD.A.Bender,K.M.Botham,P.A.Weil,P.J.Kennelly,R.K.Murray,V.W.Rodwell(Eds),Harper'sIllustratedBiochemistry,29e.
6.ThepredominantisozymeofLDHinLungis: a)LD-1 b)LD-2 c)LD-3 d)LD-5 CorrectAnswer-CIsoenzymesofLactateDehydrogenase:Lactatedehydrogenaseisatetramericenzymeandconsistsoffoursubunits.Thesesubunitscanoccursintwoisoformsi.e.Hisoform(forheart),Misoform(formuscle).LDH-1(4H)-intheheartandRBCsLDH-2(3H1M)-inthereticuloendothelialsystemLDH-3(2H2M)-inthelungsLDH-4(1H3M)-inthekidneys,placenta,andpancreasLDH-5(4M)-intheliverandstriatedmuscleNormalvalueofLDHinserumis100-200U/L.LDHlevelis100timesmoreinsidetheRBCthaninplasma,andthereforeminoramountofhemolysiswillresultinafalsepositivetest. Ref:Harper'sIllustratedBiochemistry,26thEdition,Page57;TextbookofBiochemistryByVasudevan,5thEdition,Page53
7.Substratelevelphosphorylationoccurinstepcatalysedbywhichofthefollowing enzymeinTCAcycle? a)Isocitratedehydrogenase b)Malatedehydrogenase c)Aconitase d)Succinatethiokinase CorrectAnswer-DSuccinatethiokinaseistheenzymethatgeneratesATPdirectlybysubstrate-levelphosphorylation.InKrebscyclesuccinatethiokinasecatalyzetheconversionofSuccinylCoAintosuccinate.InthisstepGDPisphosphorylatedtoGTP.GTPcanthenbeconvertedtoATPbyreactingwithanADPmolecule.Substrate-levelphosphorylationisatypeofmetabolismthatresultsintheformationandcreationofadenosinetriphosphate(ATP)orguanosinetriphosphate(GTP)bythedirecttransferanddonationofaphosphoryl(P03)grouptoadenosinediphosphate(ADP)orguanosinediphosphate(GDP)fromaphosphorylatedreactiveintermediate.Inglycolysissubstratelevelphosphorylationoccurintwosteps:Conversionof1,3BPGto3PhosphoglyceratecatalyzedbyPhosphoglyceratekinaseConversionofPhosphoenolpyruvatetopyruvatecatalyzedbyPyruvatekinaseRef:TextbookofBiochemistryByDMVasudevan,3rdEdition,Page195
8.Phosphofructokinase-1occupiesakeypositioninregulatingglycolysisandis alsosubjectedtofeedbackcontrol.Whichamongthefollowingistheallostericactivatorsofphosphofructokinase-1? a)Fructose2,3bisphosphate b)Fructose2,6bisphosphate c)Glucokinase d)PEP CorrectAnswer-BThemostpotentpositiveallostericactivatorofphosphofructokinase-1andinhibitoroffructose1,6-bisphosphataseintheliverisfructose2,6-bisphosphate.Itrelievesinhibitionofphosphofructokinase-1byATPandincreasestheaffinityforfructose6-phosphate.Itinhibitsfructose1,6-bisphosphatasebyincreasingtheKmforfructose1,6-bisphosphate. Itsconcentrationisunderbothsubstrate(allosteric)andhormonalcontrol(covalent modification).Phosphofructokinase-1isinhibitedbycitrateandbynormalintracellularconcentrationsofATPandisactivatedby5'AMP.Ref:BenderD.A.,MayesP.A.(2011).Chapter20.Gluconeogenesis&theControlofBloodGlucose.InD.A.Bender,K.M.Botham,P.A.Weil,P.J.Kennelly,R.K.Murray,V.W.Rodwell(Eds),Harper'sIllustratedBiochemistry,29e.
9.Enzymesofglycolysisarefoundin: a)Cytosol b)Cellmembrane c)Mitochondria d)Ribososmes CorrectAnswer-AAlloftheenzymesofglycolysisarefoundinthecytosol.Ref:Harper28thedition,chapter18.
10.TheFentonreactionleadstofreeradicalgenerationwhen: a)Radiantenergyisabsorbedbywater b)Ferrousionsareconvertedtoferricions c)Nitricoxideisconvertedtoperoxynitriteanion d)Hydrogenperoxideisformedby,myeloperoxidase CorrectAnswer-BFentonreactioninvolvestheferrousironcatalyzedconversionofhydrogenperoxideintoahydroxideionandahydroxylfreeradicalwiththeconcurrentoxidationofferrousirontoferriciron.Fentonreaction:H.J.HFentondiscoveredin1894thatseveralmetalshaveaspecialoxygentransferpropertieswhichimprovetheuseofhydrogenperoxide.Actually,somemetalshaveastrongcatalyticpowertogeneratehighlyreactivehydroxylradicals(.OH).Sincethisdiscovery,theironcatalyzedhydrogenperoxidehasbeencalledFenton'sreaction.HydrogenperoxideisconvertedtohydroxylradicalsintheFentonreaction.Theironcanexistinanumberofdifferentoxdationstates.Thereforetheoxidationoffe2+byh2o2canproceedthroughaoneelectrontransferoratwoelectrontransfer.Fentonsreactionisaninnersphereoneelectrontransferprocess.Theh2o2formsacomplexwithfe2+beforeelectrontransfertakesplace.Afteradditionoftheironandthehydrogenperoxide,theyaregoingtoreacttogethertogeneratesomehydroxylradicalsasitshowsinthefollowingequations:Fe2++H2O2---->Fe3++.OH+OH-Fe3++H2O2---->Fe2++.OOH+H+Importance:Hydroxylradicalsarethemostpowerfulofthereactiveoxygenspecies.Itiscapableofdestroyinganyorganicmolecule.Uses:Usedtotreatalargevarietyofwaterpollutionsuchasphenols,formaldehyde,BTEX,pesticidesandrubberchemicals.Ref:FreeRadicalsinMedicine,ByRaduOlinescu,Dr.TerranceL.Smith,Page28
11.Themechanismofactionofuncouplersofoxidativephosphorylationinvolves: a)InhibitionofATPsynthase b)StimulationofATPsynthase c)Disruptionofprotongradientacrosstheinnermembrane d)Disruptionofprotongradientacrossoutermembrane CorrectAnswer-CUncouplersareproteincarriersthatcanfreelypassthroughtheinnermitochondrialmembrane.Itallowstranslocationoftheprotonsintotheintermembranousspaceduringtheelectrontransportintherespiratorychainbutblockstheformationofprotongradientacrosstheinnermitochondrialmembrane.Thermogeninaproteinpresentintheinnermitochondrialmembraneofadipocytesisanexampleofphysiologicuncouplersofoxidativephosphorylation.Examplesofuncouplersare:2,4dinitrophenol,pentachlorophenol,nigericin,thyroxinandthermogenin.Ref:Jaypee'sReviewofMed.BiochemistryByS.M.Rajupage102.
12.Whichofthefollowingistheratelimitingstepincholesterolsynthesis? a)HMGCoAsynthase b)HMGCoAreductase c)Thiokinase d)Mevalonatekinase CorrectAnswer-BInitiallyincholesterolsynthesis,twomoleculesofacetyl-CoAcondensetoformacetoacetyl-CoAcatalyzedbycytosolicthiolase.Acetoacetyl-CoAcondenseswithafurthermoleculeofacetyl-CoAcatalyzedbyHMG-CoAsynthasetoformHMG-CoA,whichisreducedtomevalonatebyNADPHinareactioncatalyzedbyHMG-CoAreductase.Thislaststepistheprincipalregulatorystepinthepathwayofcholesterolsynthesisandisthesiteofactionofthemosteffectiveclassofcholesterol-loweringdrugs,thestatins,whichareHMG-CoAreductaseinhibitors.Ref:BothamK.M.,MayesP.A.(2011).Chapter26.CholesterolSynthesis,Transport,&Excretion.InD.A.Bender,K.M.Botham,P.A.Weil,P.J.Kennelly,R.K.Murray,V.W.Rodwell(Eds),Harper'sIllustratedBiochemistry,29e.
13.Whichoneofthefollowingcanbeahomologoussubstitutionforisoleucinein aproteinsequence? a)Methionine b)Asparticacid c)Valine d)Arginine CorrectAnswer-CIsoleucineisoneoftheaminoacidwithanaliphaticsidechain.Otheraminoacidswithanaliphaticsidechainisglycine,alanine,valineandleucine.Amongtheoptionsprovided,valineistheonlyaminoacidwithanaliphaticsidechainandsoitcanbeahomologoussubstitutionforisoleucineinaproteinsequence.Ref:Harper'sIllustratedBiochemistry,26thEdition,Chapter3,Page15;HumanGeneEvolutionByDavidN.Cooper,1999,Page299.
14.Albinismisduetodeficiencyofthefollowingenzyme? a)Phenylalaninehydroxylase b)Homogentisicacidoxidase c)Tyrosinase d)Decarboxylase CorrectAnswer-CThemostcommoncauseofalbinismisadefectintyrosinase,theenzymemostresponsibleforthesynthesisofmelanin.Albinismisaninbornerrorduetolackofsynthesisofmelanin.Itisanautosomalrecessivedisorderwithafrequencyof1in20,000. Ref:TextbookofBiochemistryandHumanBiologybyG.P.Talwar,3rdEd,Page452
15.Whichamongthefollowingglucosetransporterpresentinbetacells? a)GLUT1 b)GLUT2 c)GLUT3 d)GLUT4 CorrectAnswer-BGLUT2istheglucosetransporterpresentinthebetacellsandlivercells.IthasahighKmforglucose.Henceentryofglucoseisdirectlyproportionaltotheglucoselevel.Itisaninsul;inindependenttransport.GLUT3ispresentinbrainandGLUT4meditesinsulindependenttransportofglucoseintomuscleandadiposetissue.Ref:MurrayR.K.,GrannerD.K.(2011).Chapter40.Membranes:Structure&Function.InD.A.Bender,K.M.Botham,P.A.Weil,P.J.Kennelly,R.K.Murray,V.W.Rodwell(Eds),Harper'sIllustratedBiochemistry,29e.
16.Whatistheroleofcataboliteactivatorprotein(CAP)inLACoperon? a)Positiveregulator b)Negativeregulator c)Attenuation d)Constitutiveexpression CorrectAnswer-ACataboliteactivatorprotein,CAPisanactivatorrequiredforhighleveltranscriptionofthelacoperon.CAPproteinexertspositivecontrolandlacrepressorexertsnegativecontrol.WhatisanOperon?Inprokaryotes,thegenescodingforproteinsinvolvedinaparticularmetabolicpathwayareoftensequentiallyarranged-togetheronthechromosomealongwithasinglepromoterorregulatoryregion.Thisentireclusteristermedasanoperon,foreg,thelacoperon(codingproteinsformetabolismoflactose)ortrpoperon(codingproteinsneededforthesynthesisoftryptophan).Lacoperon:LacoperoncontainslacZ,lacYandlacAgenesencodingbetagalactosidase,galactosepermeaseandthiogalactosidetransacetylaseandisprecedbyanoperator(O)siteandpromoter(P)site.TheoperonistranscribedbyRNApolymerasetoproduceasinglepolycistronicmRNAthatistranslatedtoproduceallthreeenzymeswhichareinvolvedinlactosemetabolism.
17.Trueaboutglutamatedehydrogenaseis A/E a)Livermitochondrialenzyme b)UsebothNAD*orNADP+coenzyme c)InhibitedbyADP&activatedbyGTP d)Reversibleoxidativedeamination CorrectAnswer-CCi.e.InhibitedbyADP&activatedbyGTPDuringfirstfewdaysoffasting,thereisrapidbreakdownofmuscleprotein,providingaminoacids(alanine&glutaminemainly)thatareusedbyliverforgluconeognesisQ.Inthefastingstate,theoutputofalaninefromskeletonmuscleisinfarexcessofitsconcentrationinthemuscleproteinsthatarebeingcatabolized.Becauseitisalsoformedbytransaminationofpyruvateproducedbyglycolysisofmuscleglycogen.Alanineisexportedtotheliver,whereitistransaminatedbacktopyruvate,whichservesasasubstrateforgluconeogenesisQ.
18.Amongthefollowing,themaximumredox potentialisfor: a)NADH/NAD b)Succinate/Fumarate c)Ubiquinone d)Fe+3/Fe+2 CorrectAnswer-DAns.Di.e.Fe+3/Fe+2Becauseelectronstendtoflowspontaneouslyfromcarriesoflowerredoxpotential(E?)tocarriesofhigherredoxpotential.Theorder(sequence)ofelectroncarriersinETCofmitochondria(andsotheincreasingorderofredoxpotential)isSubstrate-->NADP+/NADPH-->NADVNADH-->NADHdehydrogenase(FMN)/NADHdehydrogenase(FMNH2)-->FAD/FADH2-->UbiquinoneorCoenzymeQ-->Fe3+/Fee*incytochromesb-->C-->a-+a3-->02
19.(-oxidationofpalmiticacidyields a)3acetylCoA b)129ATPnet c)131ATPnet d)16AcetylCoA CorrectAnswer-BBi.e.129ATPnet
20.Refsum'sdiseaseisduetodeficiencyof whichofthefollowingenzyme? a)Malonatedehydrogease b)Thiophorase c)Succinatethiokinase d)Phytanicalphaoxidase CorrectAnswer-DDi.e.PhytanicalphaoxidaseRefsum'sdiseaseisarareautosomalrecessivedisordercausedbydeficiencyofphytanicaoxides(Nelson)/a?hydroxylase(Lippincot)/PhytanoylCoAhydroxylase(Lehninger)resultsinaccumulationofphytanicacidduetoitsdecreaseda-oxidation(i.e.hydroxnlationatacarbonbyfattyacidahydroxylase)
21.Energysourceusedbybraininlaterdays ofStarvationis a)Glucose b)Ketonebodies c)Glycogen d)Fattyacids CorrectAnswer-BBi.e.Ketonebodies
22.Instarvation,nitrogeniscarriedfrom muscletoliverandkidneyby: a)Alanine b)AsparticacidandSerine c)Glycine d)Asparagines CorrectAnswer-AAi.e.AlanineInstarvation,alanineandglutaminearequantitativelythemostimportantgluconeogenicaminoacidsQ.Soalaninecarriesnitrogenfrommuscletoliver&kidneyforfurthermetabolism&energyproductionduringstarvation.
23.ThegapsbetweensegmentsofDNAon thelaggingstrandproducedbyrestrictionenzymesarerejoinedsealedby: a)DNALigases b)DNAHelicase c)DNAtopoisomerase d)DNAphosphorylase CorrectAnswer-AAi.e.DNALigases
24.Replicationandtranscriptionaresimilar processesinmechanistictermsbecauseboth: a)UseRNAprimersforinitiation. b)Usedeoxyribonucleotidesasprecursors. c)Aresemiconservedevents d)Involvephosphodiesterbondformationwithelongation occurringinthe5'-3'direction CorrectAnswer-DDi.e.Involvephosphodiesterbondformationwithelongationoccurringinthe5'-3'direction.InbothDNAandRNAsynthesis,thegeneralstepsofinitiation,elongationandterminationoccurin5'-3'directionwiththeformationofphosphodiesterbondsQ.
25.
Theanticodonregionisanimportantpartofthe a)r-RNA b)m-RNa c)t-RNa d)hn-RNa CorrectAnswer-CCi.e.t-RNA
26.Kmvalueisdefinedas: a)SubstrateconcentrationatVmax/2 b)SubstrateconcentrationoftwiceVmax c)SubstrateconcentrationofthriceVmax d)SubstrateconcentrationofonethirdVmax CorrectAnswer-AAns.A.SubstrateconcentrationatVmax/2
27.Enzymeactivityisexpressedas: a)Millimoles/lit? b)Milligm/lit? c)Mg/dl d)Micromoles/min CorrectAnswer-DAns.is.D.Micromoles/min
28.Whichofthefollowingisaserine protease a)Chymotrypsin b)Pepsin c)Carboxypeptidase d)Caspases CorrectAnswer-AAns.is'a'i.e.,ChymotrypsinlRef:Chatterjee7h/ep.4j5-361*ThetermProteaseisusedtorepresentthegroupofenzymesthatcatalyzethecleavageofpeptidebondsinproteinsandpeptidemoleculeswiththeparticipationofwaterasco-reactant.Insimplewords,proteasescatalyzethecleavageofpeptidebondsbyhydrolysis(additionofwaterSerineproteases:-*Thesepossesacriticalserineresidueattheactivesite.-Exampleofserineproteasesaretrypsin,chymotrypsin,elastase,andthrombin.*Serineproteasesareinhibitedbydisopropylphosphofluridatewhichbindscovalentlytoserineresidue.-Theactivesiteofserineproteasescontainthreecriticalaminoacidsserine,histidineandaspartate.Theseresiduesareoftenreferredtoascatalytictriad
29.Creatinineisformedfrom: a)Arginine b)Lysine c)Leucine d)Histamine CorrectAnswer-AGlycine,arginineandmethionineallparticipateincreatinebiosynthesis
30.Acidicaminoacidsare- a)Asparagine b)Arginine c)None d)Lysine CorrectAnswer-AProlineisauniqueaminoacidandhasanimminogroup(=NH)insteadofanamino(NH2)groupfoundinotheraminoacid.Methionine&Cysteinearesulfurcontainingaminoacids.Thepropertyofphotochromicity(i.e.absorbanceofultravioletlightat250-290nmesp280nm)isseenwitharomaticaminoacid(tryptophan>tyrosine>phenylalanine).Hydrophobic(nonpolar)aminoacidshavenochargeontheirRgrouporsidechain.Aliphatic(egmethyl,methylene,thioether&imino)sidechainsandaromaticsidechainsarenonpolar.Somethyl(CH3)sidechainofalanine;propyl(C3H7)sidechainofvaline;butyl(C4H9)sidechainofleuicine&isoleucine;thioethersidechainofmethionine;andiminogroup/pyrrolidinecontainingsidechainofprolinearenonpolar.Methyl(CH3)sidechainofalanineisnonpolar.Serine,threonine,tyrosinecontaininghydroxylgroupandcysteinecontainingsulfhydrylgroup,arepolaraminoacidswithneutral/uncharged/nonionicsidechain.Positivelychargedbasicamino(NH + 3 )groupsidechainof histidine,arginineandlysine;andnegativelyacidiccarboxyl(COO-)sidechainofasparticacidandglutamicacidispolar.
31.Non-Essentialaminoacidis- a)Tyrosine b)Phenylalanine c)Lysine d)Threonine CorrectAnswer-AAns.A.Tyrosine
32.Detergentactionofbilesaltsisdueto: a)Hydropathic b)Actsasazwitterion c)Amphipathic d)All CorrectAnswer-CAns.C.Amphipathic
33.Hemesynthesisrequires a)Ferrousiron b)Glycine c)SucchylCoA d)All CorrectAnswer-D
34.Tumorsuppressorgeneisnotinvolvedin ? a)Breastcancers b)Neurofibromatosis c)Multipleendocrineneoplasia d)Retinoblastoma CorrectAnswer-CoMultipleendocrineneoplasiainvolvesRETprotooncogene(nottumorsuppressorgene).
35.InEndometrialcarcinoma,whichofthe followingtumorsuppressorgeneoccurs? a)P53 b)Rb c)PTEN d)APC CorrectAnswer-CPTENisatumorsuppressorgenewhichisimplicatedinthecausationofendometrialandprostatecarcinoma.
36.Telomerase- a)RNApolymerase b)Causescarcinogenesis c)Presentinsomaticcells d)Absentingermcells CorrectAnswer-BTelomeraseisaDNApolymerase(RNAdependentDNApolymerase)whichispresentingermcellsandisabsentfrommostsomaticcells.Thustelomeraseactivityandmaintenanceoftelomerelengthareessentialforthereplicativepotentialincancercells.
37.Ecadheringenedeficiencyisseenin- a)Gastricca b)Intestinalca c)Thyroidca d)Pancreaticca CorrectAnswer-AThemajorityofgastriccancersarenothereditary,themutationsidentifiedinfamilialgastriccancerhaveprovidedimportantinsightsintomechanismofcarcinogenesisinsporadiccancers.GermlinemutationsinCDHI,whichencodesEcadherin,aproteinthatcontributestoepithelialintercellularadhesionareassociatedwithfamilialgastriccancers,whichareusuallyofdiffusetype.MutationsinCDH1arepresentinabout50%ofsporadiccasesofdiffusegastriccancers,whileEcadherinexpressionisdrasticallydecreasedintherest,oftenbymethylationoftheCDHIpromotor.Lobularcarcinomaofbreastwhichalsotendstoinfilterateassinglecells,&individualswithBRCA2mutationsareatincreasedriskofdevelopingdiffusegastriccancers.
38.Li?Fraumenisyndromeisduetomutation ofwhichgene- a)P21 b)P53 c)P41 d)P43 CorrectAnswer-BCancerarisesthroughaseriesofsomaticalterationsinDNAthatresultinuncontrolledcelldivision.Humancancershavefollowingimportantetiologicalfactors?GeneticpredispositiontocancerNon-hereditarypredisposingconditionsGeographicandenvironmentalfactorsGenetic(Hereditaryorinherited)predispositiontocancerAlargenumberofcancershavehereditarypredispositions.Geneticpredispositionmaybeofthreetypes.AutosomaldominantInheritedcancersyndromesThisisthemostcommontypeofgeneticpredisposition.Themechanisminvolvesuncontrolledcelldivisionduetogermlinemutationofcancersuppressorgene. Gene Inheritedpredisposition RB Retinoblastoma p53 Li-fraumenisyndrome pl6INK4A MelanomaFamilialadenomatouspolyposis/colon APC cancer NF-1,NF-2 Neurofibromatosis1and2 BRAC-1,BRAC-2 Neurofibromatosis1and2
BRAC-1,BRAC-2 Neurofibromatosis1and2 MEN1,RET Multipleendocrineneoplasia MSN2,MLH1,MSH Heriditarynonpolyposiscoloncancer 6PATCH Nevoidbasalcellcarcinomasyndrome 2.DefectiveDNArepairsyndromeBesidethedominantlyinheritedprecancerousconditions,agroupofcancerpredisposingconditionsiscollectivelycharacterizedbydefectsinDNArepair.Normally,iftheDNAdamageispresentitisrepairedatcell-cyclecheckpoints.IfDNArepairmechanismisdefective,cellsreplicatewithdefectiveDNAandmutationsorchromosomalbreaksaretransferedintheprogenyofcellsthatcanleadtouncontrolledreplication.Mostoftheseconditionsareinheritedasautosomalrecessive,e.g? 1. Xerodermapigmentosa2. Fanconisyndrome3. Bloomsyndrome4. Ataxiatelangectasia Oneconditioninthisgroupisautosomaldominantheriditorynonpolypidcoloncancer(HNPCC).3.FamilialcancersBesidestheinheritedsyndromesofcancersusceptibility,somecancersoccurathigherfrequencyincertainfamilieswithoutaclearlydefinedpatternoftransmission.Thatmeans,thereisfamilialclusteringofcases,butroleofinheritedpredispositionisnotclearforeachindividual.Example-Breast,ovarian,andpancreaticcancers.
39.Whichelementisrequiredby phosphofructokinase? a)Magnesium b)Inorganicphosphate c)Manganese d)Copper CorrectAnswer-APhosphofructokinase(PFK)is--300aminoacidsinlength,andstructuralstudiesofthebacterialenzymehaveshownitcomprisestwosimilar(alpha/beta)lobes:oneinvolvedinATPbindingandtheotherhousingboththesubstrate-bindingsiteandtheallostericsite(aregulatorybindingsitedistinctfromtheactivesite,butthataffectsenzymeactivity).Theidenticaltetramersubunitsadopt2differentconformations:ina'closed'state,theboundmagnesiumionbridgesthephosphorylgroupsoftheenzymeproducts(ADPandfructose-1,6-bisphosphate);andinan'open'state,themagnesiumionbindsonlytheADP,asthe2productsarenowfurtherapart
40.CarbamoylphosphatesynthetaseIis: a)Lysosolicenzyme b)Cytosolicenzyme c)Mitochondrialenzyme d)Alloftheabove CorrectAnswer-CMitochondrialcarbamoylphosphatesynthetaseIisanenzymethatcatalyzesareactionthatproducescarbamoylphosphate.ThisenzymecatalyzesthereactionofATPandbicarbonatetoproducecarbonylphosphateandADP.CarbonylphosphatereactswithammoniatogivecarbamateCytosoliccarbamoylphosphatesynthetaseIIusesglutamineratherthanammoniaasthenitrogendonorandfunctionsinpyrimidinesynthesis.
41.Whichofthefollowingisrequiredfor propereffectsofInsulin? a)Selenium b)Iron c)Copper d)Chromium CorrectAnswer-DInassociationwithinsulin,chromiumpromotestheutilizationofglucoseChromiumisacomponentofaproteinnamelychromodulinwhichfacilitatesthebindingofinsulintocellreceptorsitesChromiumItisanessentialnutrientforthemaintenanceofnormalglucosetoleranceItsdeficiencycausesinsulinresistance.Chromiumadministrationhasalsobeenshowninseveralstudiestolowerglucoseandinsulinlevelsinpatientswithtype2diabetes.Ithasbeenclassifiedasnotessentialformammals.(Cr(III)orCr3+).Chromiumdeficiencyiscontroversialorisatleastextremelyrare.Ithasbeenattributedtoonlythreepeopleonparenteralnutrition,whichiswhenapatientisfedaliquiddietthroughintravenousdrips.Incontrast,hexavalentchromium(Cr(VI)orCr6+)isverytoxicandmutagenicwheninhaled.Cr(VI)hasnotbeenestablishedasacarcinogenwheninsolution,althoughitmaycauseallergiccontactdermatitis(ACD).Dietarysupplementsforchromiumincludechromium(III)picolinate,chromium(III)polynicotinate,andrelatedmaterials.
chromium(III)polynicotinate,andrelatedmaterials.GlutathioneperoxidaserequiresseleniumCopperisanimportantconstituentofcatalse,cytochromeoxidaseandtyrosinase.Zincisalsonecessaryforthestorageandsecretionofinsulin
42.Glycemicindexisdefinedas: a)Glucosecontrolinlast3months b)Measureofthechangeinthebloodglucosefollowingingestion ofproteins c)Measureofthechangeinthebloodglucosefollowingingestion ofcarbohydrate d)Measureofthechangeinthebloodglucosefollowingingestion offats. CorrectAnswer-CTheGlycemicindex(GI)ofacarbohydratecontainingfoodisameasureofthechangeinthebloodglucosefollowingitsingestion
43.Whichofthefollowingisknownas suicidalenzyme? a)Lipoxygenase b)Cyclooxygenase c)Thromboxanesynthatase d)5'nucleotidase CorrectAnswer-BSuicidalenzymeisone,whichundergoesself-destructioninordertoterminateitsownacitivity,e.g.Cyclooxygenase.SuicidalInhibitionisconversionofasubstratebytheenzymeintoametabolite,whichisapotentinhibitoroftheenzyme;example:Xanthineoxidaseconvertsallopurinoltoalloxanthine(oxypurinol),whichisamorepotentinhibitorofallopurinol.Cycloorygenaseisknownassuicideenzymebecauseitcatalyzesitsowndestruction.
44.Whichofthefollowingenzymeisnota componentoffattyacidsynthasecomplex? a)AcetylCo-Acarboxylase b)Ketoacylsynthase c)Enoylreductase d)Acetoacetyl CorrectAnswer-ATheFattyAcidSynthaseComplexIsaHomodimerofTwoPolypeptideChainsContainingSixEnzymeActivitiesandtheAcylCarrierProtein.The6enzymesare-KetoacylsynthaseKetoacylreductaseMalonyltransacylaseDehydrataseEnoylreductaseThioesteraseAcetylCo-Acarboxylaseistherate-limitingenzymeoffattyacidsynthesisandisanenzyme,whichisnotacomponentoffattyacidsynthasecomplex.
45.Umamitasteisevokedby? a)Glucose b)Glutamicacid c)Quinine d)Sodiumchloride CorrectAnswer-BAns.is'b'i.e.,GlutamicacidTherearefourbasictastesnamelySweet,bitterSaltyandSour.Theremechanismsofsensorytransductionare:1)SweetreceptorisaGproteincoupledreceptorandleadstoanincreaseincAMPconcentrationinthesensorycellswhichresultsinclosureofK+channelsanddepolarization.2)BitterreceptorsarealsoGproteincoupledreceptorsandcausesriseinintracellularCa'byIP3-DAGsystem.RiseinintracellularCa+2triggersneurotransmitterrelease.3)Salty-tastingsubstancesdepolarizetastecellsbyactivatingamiloride-sensitiveNa+channels.4)Sour-tastingsubstancesdepolarizetastecellsbyraisingtheintracellularH+ionconcentration,whichcausesclosureofK+channels.Theumamitasteisthefifthtastewhichisunique.Theproposedmechanismofumamitasteisthroughglutamatetastesensors(glutamatereceptors)withreleaseofneuronalglutamicacid.Innature,therearethreeumamisubstances:-i)Monosodiumglutamate(MSG)ii)Disodium51-guanosinemosphosphate(GMP)iii)Disodium51-ionsinemonophosphate(IMP)
46.Sirtuinsareassociatedwith? a)Memory b)Metabolism c)Vision d)Olfaction CorrectAnswer-BAns.is'b'i.e.,MetabolismSirtuinsareafamilyofhighlyconservedNAD+dependentdeacetylase5thatactascellularsensorstodetectenergyavailabilityandmodulatemetabolicprocess.Twomammaliansirtuinsareinvolvedincontrolingmetabolicprocess:SIRT-1(innucleus)andSIRT-2(inmitochondria).TheyareactivatedbyhighNAD?levels(lowcellularenergystatus).They,then,deacetylateavarietyofproteinscausinginductionofcatabolicprocessesandinhibitionofanabolicprocesses.SIRT-1andSIRT-3coordinatelyincreasecellularenergystoresandultimatelymaintaincellularenergyhomeostasis.GeneticvariantinSIRT-1geneisassociatedlowerriskofcardiovascularmortalityandwithbettercognitivefunctioning.SIRT-1variantsareassociatedwithdecreasedbasalenergyexpenditureandalowerlipidperoxidationrate.Therefore,ithasbeenproposedthatgeneticvariationinSIRT-1maydeterminetheresponseratesofindividualesundergoingcaloricrestrictionandincreasedphysicalactivity.GeneticvariantsofSIRT-3maybeassociatedwithincreasedlongevity(increasedlifespan),butthereisnoevidenceofsuchanassociation.
47.Normaluricacidlevelis? a)1-2mg/dl b)2-3mg/dl c)3-6mg/dl d)10-15 CorrectAnswer-CAns.is'c'i.e.,3-6mg/dl
48.Allaretrueaboutphosphorusexcept? a)Comprises1%ofthetotalbodyweight b)85%remainsinthebones c)Dietisnotacommonsource d)ParathormoneactsonNaPiIIcreceptors CorrectAnswer-DAns.is'd'i.e.,ParathormoneactsonNaPilicreceptors
49.CarbohydrateinABObloodgroup antigensis? a)Glucose b)Fructose c)Inulin d)Maltose CorrectAnswer-BAns.'b'FructoseABOantigensareglycoproteins,i.e.saccharides(carbohydrates)linkedwithpolypeptides.Therearefourmaingroups:BloodgroupA:ContainingAantigenBloodgroupB:ContainingBantigenBloodgroupAB:Containingboth'A'and'EVantigenBloodgroup0:NoABOantigen'A'and'EVantigensarederivedfromH-antigen.H-antigenisformedbyaddingfucosetoterminalgalactoseofbackbonestrucuture.TheadditionofN-acetyl-D-galactosamineorD-galactosetothegalactoseresidueofH-antigenconfers'A'or'B'antigen,respectively.
50.Inargininosuccinasedeficiency,what shouldbesupplementedtocontinuetheureacycle? a)Aspartate b)Arginine c)Citrullin d)Argininosuccinate CorrectAnswer-BArgininosuccinase(argininosuccinatelyase)catalyzesthecleavageofargininosuccinateintoarginineandfumarate.Thus,inargininosuccinasedeficiency,argininecannotbeproduced.Supplementationwithargininebasehelpsreplenishthisaminoacid.
51.Tay-Sachdiseaseisduetodeficiencyof a)HexosaminidaseA b)HexosaminidaseB c)Sphingomyelinase d)-galactosidase CorrectAnswer-AAns.is.A.HexosaminidaseA
52.Maximumenergyisliberatedby hydrolysisof? a)Creatinephosphate b)ATP c)Phosphoenolpyruvate d)Glucose-6-phosphate CorrectAnswer-CAns.C.PhosphoenolpyruvateAcompoundthatliberates7Kcal/n:olormoreonhydrolysisiscalledhighenergycompound,oracompoundthatonhydrolysisundergoesalarge(.7kcal/mol)decreaseinfreeenergy(AG)understandardconditioniscalledhighenergycompound,i.e.,AG-7Kcal/mol.
53.Whichofthefollowingisanaldose sugar? a)Ribulose b)Fructose c)Glyceraldehyde d)Alloftheabove CorrectAnswer-CAns.C.Glyceraldehyde Numberof Sugar Aldoses Ketoses carbonAtoms Trioses 3 Glyceraldehyde Dihydroxyacetone Tetroses 4 Erythrose Erythrulose Pentoses 5 Ribose,Xylose Ribulose,Xylulose Hexoses 6 Glucose,Galactose,Mannose Fructose Heptoses 7 Glucoheptose Sdoheptulose
54.Bondinvolvedinformationofprimary structureofprotein/polypeptide? a)Hydrogen b)Peptide c)Disulfide d)aandbboth CorrectAnswer-DAns:D.aandbbothTheprimarystructureisstabilizedbyapeptidebond,whichisatypeofcovalentbondBondsresponsibleforproteinstructureTwotypesofbondsstabilizeproteinstructure:-Covalent(strong):-Peptidebonds,Disulfidebond.Non-covalent(weak):-Hydrogenbond,hydrophobicinteractions,electrostatic(orionicorsalt)bond,VanderWaalsinteractions.
55.Mainsourceofenergyin1minis? a)Glycogen b)FFA c)Phosphates d)Glucose CorrectAnswer-ASourceofenergyformuscularactivityTheimmediatesourceofenergyforallmusclecontractionsisATP,followedimmediatelybycreatinephosphate.Instrenuousexercise,theATPstoreissufficientonlyfor1-2secondsandcreatinephosphateforanother5-7seconds.Thus,energy-richphosphagenstores(ATPandcreatinephosphate)permitseveremusclecontractionfor8-10secondsonly.Afterthis,energyisobtainedfromthemetabolismofstoredglycogenorfromcirculatingglucoseandfreefattyacids,dependingupontheavailabilityofoxygen.Energysourceduringinexercisecanbesummarizedby:-i)Theshortburstofintenseactivity(e.g.,100-metersprintorweightlifting):-AllenergycomesfromATPandcreatinephosphate.Thebreakdownofthesecompoundsisanaerobicprocesses.ii)Littlelongerintenseexercise(e.g.,200-metersprintor100-meterswim):-BesidesATPandcreatinephosphate,glycogenismetabolizedbyanaerobicglycolyticpathwaystoprovideareadysourceofenergy.So,muscleworkisanaerobic.iii)Longerdurationexercise(e.g.,jogging,marathonrun):-Themuscleworkisaerobicandenergycomesfromaerobicutilizationofglucoseandfreefattyacids.Moreglucoseisutilizedattheinitialstage,butastheexerciseisprolonged,freefattyacidsbecomethe
predominantfuel.
56.Quarternaryammoniumcompound disinfectantsare? a)Anionic b)Cationic c)Neutral d)Gases CorrectAnswer-BQuaternaryammoniumcompoundsarecationicdetergents.Theyhavemicrocidalandviricidalactivities.Theycanbeusedforinstrumentdisinfectionandskinantisepsis.
57.NotacomponentofPCR? a)Primer b)Taqpolymerase c)DNAPolymerase d)Restrictionenzyme CorrectAnswer-DStepsinPCRPCRusesDNApolymerasetorepetitivelyamlifytargetedportionofDNA.EachcycledoublestheamoutofDNAinthesample,leadingtoexponentialincreasewithrepeatedcyclesofamplification.Thusamplificationafter'n'numberofcyclein(2)".Twentycyclesprovideanamplificationof106(million)and30cyclesof109(billion).PCRoccursinfollowingsteps-i)IsolationoftargetDNAsequence:-ii)Primersconstruction:-iii)DenaturationofDNA:-iv)AnnealingofprimerstosinglestrandedDNA:-v)Chainextension:-ThusfollowingarerequiredinPCR:-TargetdoublestrandedDNA,twospecificprimers,athermostableDNApolymerase(Taqpolymerase),deoxyribonucleotides(dNTP).
58.Whichofthefollowingisincreasedin lipoproteinlipasedeficiency? a)VLDL b)LDL c)HDL d)Chylomicrons CorrectAnswer-DType1hyperlipoproteinemiasLipoproteinfractionelevated-ChylomicronsMetabolicdefect-LipoproteinlipaseorApoCIIdeficiency.Features-Eruptivexanthoma,hepatomegaly,Painabdomen.Management-Restrictionoffatintake,supplementationwithMCT
59.NADHCoQreductaseisinhibitedby? a)Rotenone b)Carbonmonoxide c)Antimycin d)Atractyloside CorrectAnswer-ARotenoneinhibitscomplexI(NADH-CoQreductase).Inhibitorsofelectrontransportchain?Inhibitorsofrespiratorychainmaybedividedintothreegroups:?1)InhibitorsofelectrontransportchainproperTheseinhibitorsinhibittheflowofelectronsthroughtherespiratorychain.Thisoccursatfollowingsites.i)ComplexI(NADHtoCoQ)isinhibitedby:-Barbiturates(amobarbital),PiericidinA(anantibiotic),rotenone(aninsectiside),chlorpromazine(atranquilizer),andguanethidine(anantihypertensive).TheseinhibitorsblockthetransferofreducingequivalentsfromFeSproteintoCoe.ii)ComplexIIisinhibitedby:-CarboxinandTTFAinhibittransferofelectonfromFADH2toCoQ,whereasmalanatecompetitivelyinhibitfromsuccinatetocomplexII.iii)ComplexIII(CytochromebtocytochromeC1)isinhibitedby:-Dimercaprol,antimycinA,BAL(Britishantilewisite),Naphthyloquinone.TheseinhibitorsblockthetransferofelectronsfromcytochromebtocytochromeCI.iv)ComplexIV(cytochromeCoxidase)isinhibitedby:-Carbonmonoxide,CN?,H2Sandazide(N3).Theseinhibitorsblockthetransferofelectronsfromcytochromeaa3tomolecularoxygenand
thereforecantotallyarrestcellularrespiration.2)InhibitorsofoxidativephosphorylationThesecompoundsdirectlyinhibitphosphorylationofADPtoATP.OligomycininhibitsFocomponentofFoF1ATPase.Atractilosideinhibitstranslocase,atransportproteinthattransportsADPintomitochondriaforphosphorylationintoATP.3)UncouplesAsthenamesuggests,thesecompondsblockthecoupelingofoxidationwithphosphorylation.ThesecompoundsallowthetransferofreducingequivalentsinrespiratorychainbutpreventthephosphorylationofADPtoATPbyuncouplingthelinkagebetweenETCandphosphorylation.Thustheenergyinsteadofbeingtrappedbyphosphorylationisdissipatedasheat.Uncouplersmaybe:-i)Natural:-Thermogenin,thyroxineii)Synthetic:-2,4-dinitrophenol(2,4-DNP),2,4-dinitrocresol(2,4-DNC),andCCCP(chlorocarbonylcyanidephenylhydrazone).
60.Ratelimitingstepinureacycleis catalyzedby? a)Arginase b)Argininosuccinase c)Carbamoyl-phosphatesynthase d)Ornithinetranscarbamylase CorrectAnswer-CAns.is'c'i.e.,Carbamoyl-phosphatesynthaseBiosynthesisofureaoccursinfivesteps.1)Carbamoylphosphatesynthase-I(CPS-I),amitochondria!enzyme,catalyzestheformationofcarbamoylphosphatebycondensationofCO,andammonia.TwomoleculesofATParerequiredforthereaction.CPS-Iistheratelimitingenzymeofureacycle.ItisanallostericenzymeandallostericallyactivatedbyN-acetylglutamate.Thereisonecytosoliccarbamylphosphatesynthase-II(CPS-II)whichusesglutamineratherthanammoniaasthenitrogendonorandfunctionsinpyrimidinesynthesis.2)Ornithinetranscarbamoylasecatalyzestheformationofcitrullinefromcarbamoylphosphateandornithine.3)Arginosuccinatesynthasecatalyzestheformationofarginosuccinatefromcitrullineandaspartate.ThisreactionrequiresIATP,but2highenergyphosphatebondsareconsumedasATPisconvertedtoAMP+PPi.Theaminogroupofaspartateprovidesoneofthetwonitrogenatomsthatappearinurea(TheotheroneisprovidedbyammoniaNH4).4)Arginosuccinatelyase(arginosuccinase)catalysesthecleavageofarginosuccinateintoarginineandfumarate.FumarateentersinTCAcycle.
TCAcycle.5)Arginasecatalysestheformationofureafromargininebyhydrolyticcleavageofargininetoyieldureaandornithine.Ornithineisthusregeneratedandcanentermitochondriatoinitiateanotherroundoftheureacycle.
61.Citrullinemiaisduetodeficiencyof? a)Argininosuccinatelyase b)Argininosuccinatesynthase c)Arginase d)Ornithinetranscarbamylase CorrectAnswer-BAns.is.B.Argininosuccinatesynthase
62.Ureaseisa/an? a)Oxidoreductase b)Lyase c)Ligase d)Hydrolase CorrectAnswer-Dfunctionally,belongtothesuperfamilyofamidohydrolasesandphosphotriesterasesHydrolases-->Alldigestiveenzymes(Pepsin,trypsin',Lipases,esterases),lysosomalenzymes'urease'andphosphatase.
63.Vitamininvolvedindecarboxylation? a)Biotin b)Pyridoxine c)Niacin d)Thiamine CorrectAnswer-BAns.is.B.PyridoxinePyridoxalphosphateisacoenzymeformanyenzymesinvolvedinamino1309acidmetabolism,especiallytransaminationanddecarboxylation.Itisalsothecofactorofglycogenphosphorylase,wherethephosphategroupiscatalyticallyimportant.Inaddition,itisimportantinsteroidhormoneaction.Pyridoxalphosphateremovesthehormone-receptorcomplexfromDNAbinding,terminatingtheactionofthehormones.
64.Nitrogen-9ofpurineringisprovidedby? a)Glycine b)Aspartate c)Glutamine d)CO2 CorrectAnswer-CIndenovosynthesis,purineringisformedfromvarietyofprecursorsisassembledonribose-5-phosphate.Precursorsfordenovosynthesisare-i)GlycineprovidesC4,C5andN7ii)AspartateprovidesN1iii)GlutamineprovidesN3andN9iv)TetrahydrofolatederivativesfurnishC2andC8v)CarbondioxideprovidesC6
65.Ratelimitingstepinfattyacidsynthesisis ? a)ProductionofacetylCoA b)Productionofoxaloacetate c)Productionofmalonyl-CoA d)Productionofcitrate CorrectAnswer-CProductionofmalonyl-CoAistheinitialandrate-limitingstepinthefattyacidsynthesis.Acetyl-CoAneedstobeconvertedtotheactivatedform,whichwillserveasthedonorofcarbonunitstothegrowingfattyacidchain.Malonyl-CoA,a3-carboncompoundissuchanactivatedform.Itisproducedbycarboxylationofacetyl-CoA,areactioncatalyzedbyacetyl-CoAcarboxylase.Acetyl-CoAcarboxylaserequiresbiotinasacofactor.ThereactionalsorequiresHCO - 3 andATP Thereactiontakesplaceintwosteps:(i)CarboxylationofbiotininvolvingHCO3andATP.(ii)transferofthecarboxylgrouptoacetyl-CoAtoformmalonyl-CoA.
66.Whichisnotacommonenzymefor glycolysisandgluconeogenesis? a)Aldolase b)Glucose-6-phosphatase c)Phosphoglyceratemutase d)Phosphoglyceratekinase CorrectAnswer-BSevenofthereactionsofglycolysisarereversibleandareusedinthesynthesisofglucosebygluconeogenesis.Thus,sevenenzymesarecommontobothglycolysisandgluconeogenesis: 1. Phosphohexoseisomerase;2. Aldolase;3. Phosphotrioseisomerase,4. Glyceraldehyde3-phosphatedehydrogenase;5. Phosphoglyceratekinase;6. Phosphoglyceratemutase;7. Enolase. Threereactionsofglycolysisareirreversiblewhicharecircumventedingluconeogenesisbyfourreactions.So,enzymesatthesestepsaredifferentinglycolysisandgluconeogenesis.
67.Whichisnotastepofgluconeogenesis? a)Conversionofglucose-6-phosphatetoglucose b)Carboxylationofpyruvate c)Conversionofoxaloacetatetophosphoenolpyruvate d)Conversionofphosphoenolpyruvatetopyruvate CorrectAnswer-DAns.'D'ConversionofphosphoenolpyruvatetopyruvateConversionofphosphoenolpyruvatetopyruvateisastepofglycolysis(notofgluconeogenesis).ReactioningluconeogenesisSevenreactionsofglycolysisarereversibleandthereforeareusedwiththesameenzymeinthesynthesisofglucosebygluconeogenesis.However,threeofthereactionsofglycolysisareirreversibleandmustbecircumventedbyfourspecialreactionsthatareuniquetogluconeogenesisandcatalyzedby(I)Pyruvatecarboxylase,(ii)Phosphoenolpyruvatecarboxykinase,iii)fructose-I,6-bisphosphatase,(iv)Glucose-6-phosphatase.Allthreeirreversiblestepsofglycolysisshouldbebypassedforgluconeogenesistooccur.Thesethreebypassstepsarecircumventedbyfourspecialreactions.A)Firstbypass(conversionofpyruvateintophosphoenolpyruvate):-Conversionofpyruvateintophosphoenolpyruvatetakesplacethroughtworeactions:?i)Carboxylationofpyruvate:-First,pyruvateentersthemitochondriaandisconvertedintooxaloacetatebypyruvatecarboxylase.Pyruvatecarboxylaseisamitochondrialenzyme,thereforethisreactionoccursinmitochondriaonly.ii)Conversionofoxaloacetatetophosphoenolpyruvate:
-Oxaloacetateproducedinthemitochondriacannotcrossthemembrane.Itisfirstreducedtomalate,whichthenmovesacrossthemitochondrialmembraneintothecytosol.Malateis,then,reoxidizedtooxaloacetateinthecytosol.Oxaloacetateisconvertedtophosphoenolpyruvatebyphosphoenolpyruvate(PEP)carboxykinase.B)Secondbypass:-Conversionoffructose-1,6-bisphosphateintofructose-6-phosphateiscatalyzedbyfructose-1,6-bisphosphatase.Itspresencedetermineswhethertissueiscapableofsynthesizingglucose(gluconeogenesis)orglycogen(gluconeogenesis)notonlyfrompyruvatebutalsofromtriosephosphate.Itispresentintheliver,kidney,andskeletalmuscle,butisprobablyabsentfromheartandsmoothmuscle.C)Thirdbypass:-Conversionofglucose-6-phosphatetoglucoseiscatalyzedbyglucose-6-phosphatase.
68.VitaminCisrequiredfor? a)Posttranslationalmodification b)Synthesisofepinephrine c)Tyrosinemetabolism d)Alloftheabove CorrectAnswer-DVitaminC(ascorbicacid)Ascorbicacid(VitaminC)isalsocalledantiscorbuticfactor.Itisveryheatlabile,especiallyinbasicmedium.Ascorbicaciditselfisanactiveform.MaximumamountofvitaminCisfoundinadrenalcortex.Ascorbicacidfunctionsasareducingagentandscavangeroffreeradicals(antioxidant).Itsmajorfunctionsare:-i)Incollagensynthesis:-VitaminCisrequiredforpost-translationalmodificationbyhydroxylationofprolineandlysineresiduesconvertingthemintohydroxyprolineandhydroxylysine.ThusvitaminCisessentialfortheconversionofprocollagentocollagen,whichisrichinhydroxyprolineandhydroxylysine.Throughcollagensynthesis,itplaysaroleinformationofmatrixofbone,cartilage,dentineandconnectivetissue.ii)Synthesisofnorepinephrinefromdopaminebydopamine-(3-monoxygenase(dopamine-13-hydroxylase)requiresVitaminC.iii)Carnitinesynthesisiv)Bileacidsynthesis:-7-a-hydroxylaserequiresvitaminC.v)Absorptionofironisstimulatedbyascorbicacidbyconversionofferrictoferrousions.vi)Duringadrenalsteroidsynthesis,ascorbicacidisrequiredduring
hydroxylationreactions.vii)Tyrosinemetabolism-OxidationofP-hydroxy-phenylpyruvatetohomogentisate.viii)Folatemetabolism-FolicacidisconvertedtoitsactiveformtetrahydrofolatebyhelpofVitaminC.
69.Firstproductofpurinemetabolism a)Uricacid b)Xanthine c)P-alanine d)CO2 CorrectAnswer-BHumanscatabolizepurinestouricacid.But,firstpurinesarecatabolizedtoxanthine,whichisfurthercatabolizedtopurine.
70.Whichofthefollowingmetabolicpathway incarbohydratemetabolismisrequiredforsynthesisofnucleicacids? a)Gluconeogenesis b)Glycolysis c)HMPshunt d)Glycogenesis CorrectAnswer-CAns.'C'HMPShunt.HMPisanalternativeroutefortheoxidationofglucose(besideglycolysis).Itisalsocalleda"pentosephosphatepathway","Dickens-Horeckerpathway","Shuntpathway"or"phosphogluconateoxidativepathway"MetabolicRoleofNADPHformedbyHMPShuntPathway1.Requiredforreductivebiosyntheses,suchasfattyacid,cholesterol,andsteroids.2.Freeradicalscavenging3.RBCmembraneintegrity4.Preventionofformationofmeth-hemoglobin5.Detoxification6.Preservingtransparencyofthelensoftheeye7.Bactericidalactivityofmacrophages8.ProductionofriboseanddeoxyriboseforDNAandRNAsynthesis.
71.Mineralrequiredforcholesterol biosynthesis? a)Fe b)Mn c)Mg d)Cu CorrectAnswer-CMgisrequiredinstage2ofcholesterolsynthesis.Biosynthesis(DeNovoSynthesis)ofcholesterolTheliveristhemajorsiteforcholesterolbiosynthesis.Somecholesterolisalsosynthesizedintheintestineadrenalcortex,gonadsandskin.Themicrosomal(smoothendoplasmicreticulum)andcytosolfractionofcellareresponsibleforfircholesterolsynthesis;However,mostofthereactionsinsynthesisoccurinthecytosol.CholesterolisaC-27compound.All27-carbonatomsofcholesterolarederivedfromasingleprecursor,i.e.acetyl-CoA(activatedacetate).Thefirsttwomoleculesofacetyl-CoAcondensetoformacetoacetyl-CoA.Next,thethirdmoleculeofacetyl-CoAcondenseswithacetoacetyl-CoAtoform3-hydroxy-3-methylglutaryl-CoA(HMG-CoA).ThenHMG-CoAisconvertedtomevalonatebyHMG-CoAreductase,thekeyregulatoryenzymeofcholesterolsynthesis.
72.SourceofenergyinKreb'scycleis- a)NAD b)NADP c)NADPH d)NADH CorrectAnswer-DAns.'D'NADHEnergeticsofTCAcycles(Kreb'scycle)Alpha-ketoglutarateisoxidativelydecarboxylatedtoformsuccinylCoAbytheenzymealpha-ketoglutaratedehydrogenase.TheNADHthusgeneratedentersintoETCtogenerateATPs.AnothermoleculeofCO2isremovedinthisstep.Thisistheirreversiblestepinthewholereactioncycle.
73.CoenzymeusedinKreb'scycle? a)NAD b)NADP c)NADPH d)NADH CorrectAnswer-ANiacinisusedascoenzymenicotinamideadeninedinucleotide(NAD')fortransferofhydrogen.
74.Mousyodorofurineisseenin? a)Alkaptunuria b)Phenylketonuria c)Hartnupdisease d)Albinism CorrectAnswer-B
75.Cabbage-likeodourisseenin? a)Alkaptonuria b)Phenylketonuria c)Hartnupdisease d)Tyrosinemia CorrectAnswer-DAns.is.D.Tyrosinemia
76.Immediateenergysupplyformuscle contraction? a)GTP b)ATP c)Creatinephosphate d)Fattyacid CorrectAnswer-CTheimmediatesourceofenergyforallmusclecontractionisATP,followedimmediatelybycreatinephosphate.TheimmediatesourceofenergyforallmusclecontractionisATP,followedimmediatelybycreatinephosphate.InsternousexerciseATPstoreissufficientonlyfor1-2secondsandcreatinephosphateforanother5-7seconds.Thus,energyrichphosphagenstores(ATPandcreatinephosphate)permitseveremusclecontractionfor8-10secondsonly.Afterthis,energyisobtainedfromthemetabolismofstoredglycogenorfromcirculatingglucoseandfreefattyacids,dependingupontheavailabilityofoxygen.Energysourceduringinexercisecanbesummarizedby:-i)Shortburstofintenseactivity(e.g.,100metersprintorweightlifting):-AllenergycomesfromATPandcreatinephosphate.Breakdownofthesecompoundisananaerobicprocesses.ii)Littlelongerintenseexercise(e.g.,200metersprintor100meterswim):-BesidesATPandcreatinephosphate,glycogenismetabolisedbyanerobicglycolyticpathwaystoprovideareadysourceofenergy.So,muscleworkisanaerobic.iii)Longerdurationexercise(e.g.,jogging,marathanrun):-The
muscleworkisaerobicandenergycomesfromaerobicutilizationofglucoseandfreefattyacids.Moreglucoseisutilizedattheinitialstage,butastheexerciseisprolonged,freefattyacidsbecomethepredominantfuel.
77.Cofactorfordopaminehydroxylase? a)Fe b)Mg c)Mn d)Cu CorrectAnswer-DDopamine8-hydroxylaseisa'copper'containingmonooxygenasethatrequiresascorbicacidandmolecularoxygen.Itcatalyzestheformationofnorepinephrine.
78.Lipoproteininvolvedinreverse cholesteroltransport? a)LDL b)VLDL c)IDL d)HDL CorrectAnswer-DTheHDLparticlesarereferredtoasscavengersbecausetheirprimaryroleistoremovefree(unesterified)cholesterolfromtheextrahepatictissues.HDLparticlestransportcholesterolfromextrahepatictissuestotheliver(i.e.reversecholesteroltransport)whichisthenexcretedthroughbile.ReversecholesteroltransportAllnucleatedcellsindifferenttissuessynthesizecholesterol,buttheexcretionofcholesterolismainlybytheliverinthebileorbyenterocytesinthegutlumen.So,cholesterolmustbetransportedfromperipheraltissuetotheliverforexcretion.ThisisfacilitatedbyHDLandiscalledreversecholesteroltransportbecauseittransportsthecholesterolinreversedirectiontothatistransportedfromthelivertoperipheraltissuesthroughtheVLDLLDLcycle.ProcessHDLissynthesizedintheliverandsmallintestine.NascentHDLcontainsphospholipidsandunesterifiedcholesterolandApo-A,C,E.ThisnascentHDLissecretedintocirculationwhereitacquiresadditionalunesterifiedcholesterolfromperipheraltissues.WithintheHDLparticle,thecholesterolisesterifiedbylecithin-cholesterolacetyltransferase(LCAT)toformcholesterylesterandadditional
lipidistransportedtoHDLfromVLDLandchylomicrons.Apo-A1activatesLCAT.
79.Allantoinistheendproductof metabolismof? a)Glycogen b)Purine c)Pyrimidine d)Histidine CorrectAnswer-BInnon-primatemammals,endproductofpurinemetabolismisallantoinduetopresenceofenzymeuricase.Uricaseconvertesuricacidtoallantoin.Humanslacktheenzymeuricase.Therefore,endproductofpurinecatabolisminhumansisuricacid.
80.Pyruvatedehydrogenasecontainsall, except- a)NAD b)FAD c)Biotin d)CoA CorrectAnswer-CPDHcomplexismadeupofthreeenzymesandrequiresfivecoenzymes.Theenzymesare:i)E1:Pyruvatedehydrogenaseorpyruvatedecarboxylaseii)E2:Dihydrolipoyltransacetylaseiii)E3:Dihydrolipoyldehydrogenase.Thecoenzymerequiredarethiaminepyrophosphate(APP),lipoicacid,FAD,NAD,andCoA.
81.Northernblotisusedtodetect? a)Protein b)Immunoglobulin c)RNA d)DNA CorrectAnswer-CAns:C.RNAVisualizationofaspecificDNAorRNAfragmentamongthemanythousandofcontaminatingmoleculesrequirestheconvergenceofnumberoftechniquescollectivelytermedtheblottransfer.SouthernblotDetectsDNANorthernblotDetectsRNAWesternblotDetectsproteins(proteinsareseparatedbyelectrophoresis,renaturedandanalysedforaninteractionbyhybridizationwithaspecificlabelledDNAprobe).
82.Notanessentialaminoacid? a)Arginine b)Histidine c)Glutamate d)Lysine CorrectAnswer-CAns'C'GlutamateEssentialorIndispensableTheaminoacidsmayfurtherbeclassifiedaccordingtotheiressentialityforgrowth.TheyareIsoleucineLeucineThreonineLysineMethioninePhenylalanineTryptophanValine
83.Enzymedeficientingangliosidoses? a)-glucuronidase b)Iduronidase c)-galactosidase d)Hyaluronidase CorrectAnswer-CAns.'C'-galactosidaseGeneralizedgangliosidosesisalipidstoragedisorder.Enzymedefect--galactosidaseLipidaccumulates-Ganglioside(GM1)Clinicalfeatures-Mentalretardation,hepatomegaly,skeletaldeformities.Foamcellsinthebonemarrow.Cherryredspotintheretina.
84.DefectintypeIIhyperlipidemia a)Apo-E b)Lipoproteinlipase c)LDLreceptor d)None CorrectAnswer-CAlsocalledFamilialhypercholesterolemia.TypeIIA(Primaryfamilialhypercholesterolemia)ThereisanelevationofLDL.Patientsseldomsurviveintheseconddecadeoflifeduetoischemicheartdisease.ThecauseistheLDLreceptordefect.ReceptordeficiencyintheliverandperipheraltissueswillresultintheelevationofLDLlevelsinplasma,leadingtohypercholesterolemia.TheLDLreceptordefectmaybeduetothefollowingreasons: 1. LDLreceptordeficiency.2. DefectivebindingofB-100tothereceptor.3. Thereceptor-LDLcomplexisnotinternalized. SecondarytypeIIhyperlipoproteinemiaisseeninhypothyroidism,diabetesmellitus,nephroticsyndrome,andcholestasis.
85.Majorsourceofenergyforbrainin fasting/starvation? a)Glucose b)Glycogen c)Fattyacids d)Ketonebodies CorrectAnswer-DThereisnostoredfuelinthebrain,butitutilized60%oftotalenergyunderrestingconditions.Glucoseisvirtuallythesolefuelforthebrain,exceptinprolongedstarvingwhenketonebodiesarethemajorsource.Fattyacidsdonotserveasfuelforthebrain,becausetheyareboundtoalbumininplasma;hencecannotcrosstheblood-brainbarrier.
86.Nicotinicacidisderivedfrom? a)Glutamine b)Tryptophan c)Glutathione d)Phenylalanine CorrectAnswer-BAns.'B'Tryptophan.NicotinicAcidPathwayofTryptophan-About97%ofmoleculesoftryptophanaremetabolizedinthemajorpathway.About3%ofmoleculesaredivertedatthelevelof3-hydroxyanthranilicacid,toformNAD+.Theenzyme,QPRT(quinolinatephosphoribosyltransferase)istherate-limitingstep.About60mgoftryptophanwillbeequivalentto1mgofnicotinicacid.Thedevelopmentofpellagralikesymptomsinthemaizeeatingpopulationisduetotryptophandeficiencyinmaize.Hydroxyanthranilateproductionisdependentonpyridoxalphosphate.HenceinvitaminB6deficiency,nicotinamidedeficiencyisalsomanifested.
87.Sexdeterminingregionislocatedon? a)LongarmofYchromosome b)ShortarmofYchromosome c)LongarmofXchromosome d)ShortarmofXchromosome CorrectAnswer-BProductofSRYgeneissex-determiningregionYprotein.Thisproteinisinvolvedinmalesexualdevelopment.
88.Transferasesareclassifiedas? a)EC-1 b)EC-2 c)EC-3 d)EC-4 CorrectAnswer-BAns.B.EC-2
89.Trueaboutacidphosphataseis? a)ActsatpH8-9 b)Prostateisoformistartarateresistant c)Erythrocyteisoformisinhibitedbycupricions d)Alloftheabove CorrectAnswer-CAcidphosphataseAcidphosphatase(ACP)hydrolyzesphosphoricacidestersatpH5-6.Itisfoundindifferentisoformsinprostate,spleen,liver,erythrocytes,plateletsandbones.Prostaticanderythrocyteisoformcanbedifferentiatedby?i)Prostaticisoformisinhibitedbytartarate(tartaratesensitive),whereaserythrocyteisoformisnot.ii)Erythrocyteisoformisinhibitedbyformaldehydeandcupricions,whereasprostaticisoformisnot.Acidphosphatase,particularlyprostaticenzyme,isunstableatroomtemperatureabove37?CandatpHabove7.0andmorethan50%oftheacidphosphataseactivitymaybelostin1houratroomtemperature.
90.Alcoholismetabolizedby? a)Alcoholdehydrogenase b)MEOS c)Catalase d)Alloftheabove CorrectAnswer-DEthylalcohol(ethanol)isreadilyabsorbedfromGITanddegradedbyoxidation(oxidativeprocess).Liveristhemajorsiteforethanoloxidation.Atleastthreeenzymesystemsarecapableofethanoloxidation:-i)Alcoholdehydrogenase(ADH)Majorpathwayii)Microsomalethanoloxidisingsystem(MEOS):ItinvolvescytochromeP450.iii)Catalaseofperoxisomes.Theproductofallthreeoxidationpathwaysisacetaldehyde,whichisrapidlyoxidizedtoacetatebyaldehydedehydrogenase(ALDH).
91.Aminoacidwhichisopticallyinert? a)Valine b)Alanine c)Glycine d)Threonine CorrectAnswer-CAns.'C'GlycineThea-carbonofaminoacidshasfourdifferentgroupsattachedtoitandsoisachiralorasymmetriccarbon.Hence,therearetwopossibleenantiomers,LandD,i.e.,mirrorimagewithreferenceto-carbon.Thechiralcarbonisalsoresponsibleforopticalactivityandstereoisomerism.Theonlyexceptionisglycine,whichisthesimplestaminoacid.Glycinehasnochiralcarbon(chirality)becausea-carbonofglycinedoesnothavefourdifferentgroupsattachedtoit.ThereforeglycinedoesnothaveopticalactivityorDandLforms(enantiomers).
92.Firstpurinenucleotide,whichis synthesizedinpurinebiosynthesis? a)AMP b)GMP c)IMP d)UMP CorrectAnswer-CThebiosynthesisofpurinebeginswithribose-5-phosphate,derivedfrompentosephosphatepathway(PPP).Firstintermediateformedinthispathway,5-phosphoribosyl-pyrophosphate(PRPP),isalsoanintermediateinpurinesalvagepathway.
93.Ratelimitingstepinhemesynthesisis catalyzedby? a)ALAdehydratase b)ALAsynthase c)UPGdecarboxylase d)Ferrochelatase CorrectAnswer-BAns.B.ALAsynthaseSynthesisofhemeHemesynthesistakesplaceinallcells,butoccurstogreatestextentinbonemarrowandliver.ThefirststepinthesynthesisofhemeisthecondensationofglycineandsuccinylCo-Atoform&-aminolevulinicacid(Delta-ALA),whichoccursinmitochondria.ThisreactioniscatalyzedbyDelta-ALAsynthasewhichrequirespyridoxalphosphate(PLP)ascofactor.Thisistheratelimitingstepinhemesynthesis.
94.Ratelimitingstepinporphyrinesynthesis - a)ALAdehydratase b)ALAsynthase c)UPGdecarboxylase d)Ferrochelatase CorrectAnswer-BAns.is.B.ALAsynthase
95.Oxidationofverylongchainfattyacids takesplacein? a)Cytosol b)Mitochondria c)Ribosomes d)Peroxisomes CorrectAnswer-DAmodifiedformof-oxidationisfoundinperoxisomesandleadstothebreakdownofvery-long-chainfattyacids(eg,C20,C22)withtheformationofacetyl-CoAandH2O2,whichisbrokendownbycatalase.ThissystemisnotlinkeddirectlytophosphorylationandthegenerationofATP,andalsodoesnotattackshorter-chainfattyacids.Theperoxisomalenzymesareinducedbyhigh-fatdietsandinsomespeciesbyhypolipidemicdrugssuchasclofibrate.Anotherroleofperoxisomal-oxidationistoshortenthesidechainofcholesterolinbileacidformation
96.Salvagepathwayofpurinebiosynthesisis importantfor? a)Liver b)RBCs c)Kidney d)Lung CorrectAnswer-BPurinenucleotidesynthesisoccursbytwopathways:1.Denovosynthesis2.SalvagepathwayLiveristhemajorsiteofpurinenucleotidebiosynthesis(denovo).Certaintissuescannotsynthesizepurinenucleotidesbydenovopatyway,eg.brain,erythrocytesandpolymorphonuclearleukocytes.Thesearedependentonsalvagepathwayforsynthesisofpurinenucleotidesbyusingexogenouspurines,whichareformedbydegradationofpurinenucleotidessynthesizedinliver.
97.Lipoproteinassociatedwithcarrying cholesterolfromperipheraltissuestoliveris? a)HDL b)LDL c)VLDL d)IDL CorrectAnswer-AThetotalbodycholesterolcontentvariesfrom130-150grams.LDL(low-densitylipoprotein)transportscholesterolfromthelivertotheperipheraltissuesandHDL(high-densitylipoprotein)transportscholesterolfromtissuestotheliver.CellsofextrahepatictissuestakeupcholesterolfromLDL.
98.Whichofthefollowingisanucleoside? a)Adenine b)Uridine c)Thymine d)Guanine CorrectAnswer-BAns.is.B.Uridine
99.AminoacidswithextraNH (aminogroup) 2 instructure- a)Aspartate b)Glutamate c)Histidine d)Alanine CorrectAnswer-CAns.is.C.HistidineTheaminoacidswillundergoalphadecarboxylationtoformthecorrespondingamine.Someimportantaminesareproducedfromaminoacids.Forexample,HistidineHistamine+CO2TyrosineTyramine+CO2TryptophanTryptamine+CO2LysineCadaverine+CO2GlutamicacidGamma-aminobutyricacid(GABA)+CO2
100.NumberofATPproducedbyRBCwhen GlycolysisoccursthroughRapoportLeuberingpathway- a)2 b)6 c)8 d)0 CorrectAnswer-DAns.'D'0NetnumberofATPsproducedfrom1molofGlucosebyAnaerobicGlycolysis-2ATPsAerobicGlycolysis-7ATPsAerobicoxidation-32ATPsRapaport-LeuberingCycle-Zero
101.Mostimportantvitamin,whichpromotes woundhealing? a)VitaminC b)VitaminD c)VitaminA d)Niacin CorrectAnswer-AVitaminCisrequiredforcollagensynthesis.Duetoitsimportantroleincollagensynthesis,vitaminCisrequiredforadequatewoundhealing.
102.Whichofthefollowingisnota glycerosphingolipid? a)Lecithin b)Cardiolipin c)Plasmalogens d)Sphingomyelin CorrectAnswer-DPhospholipidsare: i. Glycerophospholipids(glycerolcontaining):-Phosphatidylcholine (lecithin),phosphatidylethanolamine(cephaline),phosphatidylserine,phosphatidylinositol,plasmalogens,lysophospholipids,cardiolipin. ii. Sphingophospholipids(sphingosinecontaining):-Sphingomyelin
103.Immediateprecursorofcreatine a)Carbamoylphosphate b)Arginosuccinate c)Guanidoacetate d)Citrulline CorrectAnswer-CAns.'C'GuanidoacetateCreatineandcreatininearenotaminoacids,butspecializedproductsofaminoacids.Creatineissynthesizedfromglycine,arginine,andmethionine.Thesynthesisstartswiththeformationofguanidinoacetatefromglycineandarginineinthekidney.Furtherreactionstakeplaceintheliverandmuscle.
104.Tyrosineentersgluconeogenesisby formingwhichsubstrate a)SuccinylCoA b)Alpha-ketoglutarate c)Fumarate d)Citrate CorrectAnswer-CAns.'C'FumarateTCAcycleintermediatesarethesubstrateforgluconeogenesis.GluconeogenicaminoacidsentertheTCAcycleaftertheirtransaminationintovariousintermediatesoftheTCAcycle:?Histidine,proline,glutamineandarginineareconvertedtoglutamatewhichisthentransaminatedto-ketoglutarate.Isoleucine,methionineandvalineenterbyconversionintosuccinylCoA.Propionate(ashortchainfattyacid)alsoenteratthislevel.Tyrosine,andphenylalanineenterbyconversionintofumarate.Tryptophanisconvertedtoalaninewhichisthentransaminatedtopyruvate.Hydroxyproline,serine,cysteine,threonineandglycineenterbyconversionintopyruvate.
105.FumarateofTCAisderivedfrom transminationofwhichaminoacid a)Phenylalanine b)Methionine c)Valine d)Glutamine CorrectAnswer-AAns.is.A.Phenylalanine
106.AlphahelixandBetapleatedsheetare examplesof? a)Primary b)Secondarystructure c)Tertiary d)Quaternarystructure CorrectAnswer-BAns.'B'SecondarystructureStructuralorganizationofproteinsEveryproteinhasauniquethree-dimensionalstructure,whichisreferredtoasitsnativeconformationandmadeupofonly20differentaminoacids.Proteinstructurecanbeclassifiedintofourlevelsoftheorganization.1)PrimarystructuresThelinearsequenceofaminoacidresiduesandthelocationofdisulfidebridges,ifany,inapolypeptidechainconstituteitsprimarystructure.Insimplewords,theprimarystructureofproteinsreferstothespecificsequenceofaminoacids.Theprimarystructureismaintainedbythecovalent'peptide'bond.2)SecondarystructureForstabilityoftheprimarystructure,hydrogenbondingbetweenthehydrogenofNHandoxygenofC=0groupsofthepolypeptidechainoccurs,whichgivesrisetotwisting,foldingorbendingoftheprimarystructure.Thus,regularfoldingandtwistingofthepolypeptidechainbroughtaboutbyhydrogenbondingiscalledsecondarystructure.Importanttypesofsecondarystructuresarea-helix,beta-pleatedsheet,andbeta-bends.3)Tertiarystructure
Thepeptidechain,withitssecondarystructure,maybefurtherfoldedandtwistedaboutitselfformingthree-dimensionalarrangementofthepolypeptidechain,i.e.,tertiarystructurereferstotheoverallfoldingpatternofapolypeptidewhichformsthethree-dimensionalshape.Thetertiarystructure(three-dimensionalshape)ismaintainedbyweaknon-covalentinteractionswhichincludehydrogenbonds,hydrophobicinteractions,ionicbond(electrostaticbondsorsaltbridges)andVan-derwallforces.Covalentlinkage(disulfidebond)alsoplayssome(butminor)role.4)QuaternarystructureManyproteinsaremadeupofmorethanonepolypeptidechain(polymers).Eachpolypeptidechainisknownasprotomer(orsubunit).Thesubunitislinkedwitheachotherbynon-covalentbonds.Thestructureformedbytheunionofsubunitsisknownasquaternarystructure,i.e.,thespatialrelationofsubunits(peptidechains)withoneanotheriscalledthequaternarystructure.Mainlythreenon-covalentbondsstabilizequaternarystructure:Hydrophobic,hydrogenandionic(electrostatic).Dimericproteinscontaintwopolypeptidechains.Homodimerscontaintwocopiesofthesamepolypeptidechain,whileinaheterodimerthepolypeptidesdiffer.
107.RNApolymerasehaswhichactivity a)Primase b)Helicase c)Ligase d)Topoisomerase CorrectAnswer-ADNAsynthesiscannotcommencewithdeoxyribonucleotidesbecauseDNApolymerasecannotaddamononucleotidetoanothermononucleotide.Thus,DNApolymerasecannotinitiatesynthesisofcomplementaryDNAsynthesisstrandofDNAonatotallysinglestrandedtemplate.Forthis,theyrequireRNAprimer,whichisashortpieceofRNAformedbyenzymeprimase(RNApolymerase)usingDNAasatemplate.RNAprimeristhenextendedbyadditionofdeoxyribonucleotides.Lateron,theribonucleotidesoftheprimerarereplacedbydeoxyribonucleotides.PrimaseisactuallyaDNAprimasewhichhasRNApolymeraseactivity.ThisDNAprimaseisalsocalledDNApolymerase.
108.whichofthefollowingoccursonlyin mitochondria a)ECT b)Ketogenesis c)Ureacycle d)Steroidsynthesis CorrectAnswer-CAns.D.UreaCycleKetogenesisoccursprimarilyinthemitochondriaoflivercells.Fattyacidsarebroughtintothemitochondriaviacarnitinepalmitoyltransferase(CPT-1)andthenbrokendownintoacetylCoAviabeta-oxidationIneukaryotes,animportantelectrontransportchainisfoundintheinnermitochondrialmembranewhereitservesasthesiteofoxidativephosphorylationthroughtheactionofATPsynthase.Mitochondriaareessentialsitesforsteroidhormonebiosynthesis.Mitochondriainthesteroidogeniccellsoftheadrenal,gonad,placentaandbraincontainthecholesterolside-chaincleavageenzyme,P450scc,anditstwoelectron-transferpartners,ferredoxinreductaseandferredoxin.Thisenzymesystemconvertscholesteroltopregnenoloneanddeterminesnetsteroidogeniccapacity,sothatitservesasthechronicregulatorofsteroidogenesis.ureaisproducedthroughaseriesofreactionsoccurringinthecytosolandmitochondrialmatrixoflivercellsboth
109.NumberofstructuralgeneinLacoperon a)3 b)4 c)5 d)6 CorrectAnswer-ALactoseoperoneorLacoperonThelacoperonisaregionofDNAinthegenomeofE.colithatcontainsfollowinggeneticelements?i)Threestructuralgenes:-Thesecodefor3proteinsthatareinvolvedincatabolismoflactose.Thesegenesare'Z'gene(codesforP-galactosidase),'Y'gene(codesforgalactosidepermease),and'A'gene(codesforthiogalactosidetransacetylase).ii)Regulatorygene(laci)Itproducesrepressorprotein.iii)Apromotorsite(P):-ItisthebindingsiteforRNApolymerase.Itcontainstwospecificregions?a)CAPsite(Cataboliteactivatorproteinbindingsite).b)RNApolymerasebindingsiteiv)Anoperatorsite(0):-Repressorbindstothissiteandblockstranscription.3Structuralgenesareexpressedonlywhen'0'siteisempty(repressorisnotbound)andtheCAPsiteisboundbyacomplexofcAMPandCAP(catabolitegeneactivatorprotein).
110.Theenzymeinvolvedininitiationof peptidechainsynthesis- a)Topoisomerase b)Transformylase c)RNApolymerase d)Peptidyltransferase CorrectAnswer-BAns.'B'TransformylaseStepsineukaryotictranslation(proteinsynthesis)Therearethreemajorsteps,inproteinsynthesis(translation):-(i)Initiation,(ii)Elongation;and(iii)Termination.Inprokaryotesandinmitochondria,thefirstaminoacidmethionineismodifiedbyformylation,i.e.theinitiatortRNAcarriesanN-formylatedmethionine.Theformylgroupisaddedbytheenzymetransformylase(formyl-transferase).InEukaryotes,theinitiatortRNAcarriesamethioninethatisnotformylated.
111.Strongestinteractionsamongthe following a)Covalent b)Hydrogen c)Electrostatic d)VanderWaals CorrectAnswer-AAns.A.CovalentStrongestbondCovalentWeakestbondVanderwalsforcesMoleucularinteractionsTherearetwotypesofinteractionsbetweenmoleculesthatstabilizemolecularstructures:- 1. Covalentbonds,e.g.peptidebondsanddisulphidebonds.2. Non-covalentbonds.
112.Highestmobilityonelectrophoresis a)HDL b)VLDL c)LDL d)Chylomicrons CorrectAnswer-AAsinlipoproteinelectrophoresis,HDLshowsthehighestmobilityfollowedbyVLDL,IDL,andLDL.Chylomicronsmigrateaccordingtotheirnet-chargebetweenHDLandVLDLbecauseisotachophoresishasnegligiblemolecularsieveeffects.
113.RegulatingenzymesinGluconeogenesis areall,except a)Pyruvatecarboxylase b)PEPcarboxykinase c)PFK-1 d)Glucose-6-phosphatase CorrectAnswer-CAns.is.C.PFK-1
114.Glucagonstimulates a)Gluconeogenesis b)Glycogenesis c)Fattyacidsynthesis d)Glycolysis CorrectAnswer-AAns.'A'Gluconeogenesis.GlucagonisapolypeptidehormonethatissecretedbytheAcellsoftheisletsofLangerhansofthepancreas.ItactsbyincreasingcAMP.1)Glucagonstimulatesglycogenolysisintheliverbutnotinmuscle.Breakdownofglycogenyieldsglucose.2)Glucagonstimulatestheproductionofglucosefromaminoacids(gluconeogenesis).Bothglycogenolysisandgluconeogenesistendtoraiseplasmaglucoselevels.3)Glucagonstimulateslipolysis.Breakdownoflipidsyieldsfreefattyacids,whichmaybeoxidizedcompletelytocarbondioxide,orincompletelytoformketonebodies.
115.Whichofthefollowingaminoacidsis purelyketogenic? a)Phenylalanine b)Leucine c)Proline d)Tyrosine CorrectAnswer-BAns:B.)LeucineAminoacids:Ketogenic:Leucine,LysineGlucogenic:Valine,Cysteine,Serine,Alanine,Histidine,Threonine,Arginine,Glycine,Glutamate,Proline/HydroxyprolineBothGlucogenic&Ketogenic:Isoleucine,Tyrosine,Tryptophan,Phenylalanine
116.Cystathioninelyaserequireswhich cofactor? a)Thiamine b)Riboflavin c)Pyridoxine d)Niacin CorrectAnswer-CAns.'C'PyridoxineHydrolyticcleavage(hydrolysis)ofcystathionineformsHomoserinepluscysteine.Thisreactioniscatalyzedbytheenzymecystathioninelyase(cystathionase),whichrequirescofactorpyridoxalphosphate(theactiveformofpyridoxine).
117.MostcommonphysiologicalformofDNA a)A-form b)B-form c)Z-form d)C-form CorrectAnswer-BDNAcanexistinatleastsixforms,i.e.A,B,C,D,EandZ.TheB-formofDNAisthemostcommonformofDNAandisright-handedhelix.ItisthestrandardDNAstructurewith10basepairsperturn.WatsonandCrickmodeldescribestheB-formofDNA.OtherformsofDNAareA-form(contains11basepairsperturnandisrighthandedhelix)andZ-form(contains12basepairsperturnandislefthandedhelix).Z-formisfavoredbyalternatingG-Csequencesinalcoholandhighsaltsolution;andisinhibitedbyalternatingA-Tsequnces(Note-Bformhasminimumbasepairsperturn,i.e.10).
118.COactsbyinhibitingwhichcomponent ofrespiratorychain? a)Cytochromeb b)CytochromeCoxidase c)NADHCoQreductase d)Oxidativephosphorylation CorrectAnswer-BAns.'B'CytochromeCoxidaseInhibitorsofElectrontransportchain(Respiratorychain)ComplexI:-Barbiturates(amobarbital),piericidinA,rotenone,chlorpromazine,guanethidine.ComplexII:-Carboxin,TTFA,malonate.ComplexIII:-Dimercaprol,BAL,actinomycinA,Naphthyloquinone.ComplexIV(cytochromecoxidase):-Carbonmonoxide(CO),cyanide(CN),H2S,azide(N3-)
119.Specificinhibitorofsuccinate dehydrogenase? a)Fluoroacetate b)Arsenite c)Malonate d)Fluoride CorrectAnswer-CAns.C.MalonateInhibitionoftheenzymesuccinatedehydrogenasebymalonateillustratescompetitiveinhibitionbyasubstrateanalog.Succinatedehydrogenasecatalyzestheremovalofonehydrogenatomfromeachofthetwomethylenecarbonsofsuccinate.
120.Incitricacidcycle,NADHisproduced by- a)Succinatethiokinase b)Succinatedehydrogenase c)Isocitratedehydrogenase d)Fumarase CorrectAnswer-CAns'C'FumaraseNADHisproducedandCO2isliberatedat3steps:i)Conversionofisocitratetoa-ketoglutaratebyisocitratedehydrogenaseii)Conversionofalpha-ketoglutaratetosuccinylCoAbyalpha-ketoglutaratedehydrogenaseiii)ConversionofL-malatetooxaloacetatebymalatedehydrogenase.
121.Ureaissynthesizedinallexcept a)Liver b)Brain c)Kidney d)Spleen CorrectAnswer-DUreaissynthesizedinliverbutsmallquantities(notsignificant)maybeformedinbrainandkidneyalso.Ammoniaisultimatelydisposedofbyformationofureaby"Kreb'sHenseleitureacycle"intheliver.Ureacycletakesplacebothinmitochondriaandcytosol.Firsttworeactionsofureacycleoccurinthemitochondria,andremainingreactionsoccursincytosol
122.Whichofthefollowingstepisspecific forgluconeogenesis a)PyrovatetoacetylCoA b)Oxaloacetatetocitrate c)OxaloacetatetoPEP d)OxaloacetatetoPEP CorrectAnswer-CAns.is'c'i.e.,OxaloacetatetoPEP
123.Pyruvatecanbeasubstratefor a)Fattyacidsynthesis b)TCAcycle c)Cholesterolsynthesis d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,AlloftheabovePyruvateaItisadegradationproductofglucose(glycolysis)andglycogenicaminoacids.Itcanbeconvertedtoglucose(gluconeogenesisthroughoxaloacetate)andacetylCoA(thereforeallbiosyntheticproductswhicharisefromacetylCoA)
124.Inoxidativepathway,NADPHis producedin? a)Cytosol b)Mitochondria c)Ribosome d)Peroxisomes CorrectAnswer-AAns.is'a'i.e.,CytosolNADPHisproducedmainlyinHMPshunt,whichoccurscytosol.HMPisanalternativeroutefortheoxidationofglucose(besideglycolysis).Itisalsocalledas"pentosephosphatepathway","Dickens-Horeckerpathway","Shuntpathway"or"phosphogluconateoxidativepathway".HMPshuntisrequiredforprovisionofreducedNADPHandfiver-carbonsugarse.g.ribose(Pentosephosphates)fornucleicacidsynthesis.Normally,90%ofglucoseisoxidizedbyglycolysisand10%isoxidizedbyHMPshunt.However,inliverandRBCsHMPshuntaccountsforoxidationof30%glucose.HMPshuntoccursinthecytosol.Itishighlyactiveinliver,adiposetissue,adrenalcortex,lens,cornea,lactating(butnotthenonlactating)mammarygland.Gonads(testis,ovary)anderythrocytes.Activityofthispathwayisminimalinmuscleandbrain,wherealmostalloftheglucoseisdegradedbyglycolysis.
125.Glucoseisconvertedtosorbitolby? a)AldolaseB b)Aldosereductase c)Sorbitoldehydrogenase d)Allofthese CorrectAnswer-BAns.is'b'i.e.,Aldosereductase
126.Lactoseintoleranceisdueto? a)DeficiencyofGalactokinase b)DeficiencyofUridyltransferase c)DeficiencyofLactase d)DeficiencyofEnteropeptidase CorrectAnswer-CAns.is'c'i.e.,DeficiencyofLactaseLactoseintoleranceItoccursduetodeficiencyoflactase,themostimportantmemberof-galactosidaseenzymaticclass.Lactasehydrolyseslactoseintoglucoseandgalactoseinthesmallintestine.Lactoseispresentinmilk.Therefore,deficiencyoflactase,(-galactosidase)resultsinintolerancetomilkandotherdairyproducts.Clinicalfeaturesarebloating,diarrhea,failuretothrive,abdominaldistensionandabdominalcramp.
127.Deficiencyofwhichvitamincauses excretionofxantheurenicacidinurine? a)Folicacid b)Pyridoxin c)Niacin d)VitaminB12 CorrectAnswer-BAns.is'b'i.e.,Pyridoxin
128.TotalnumberofdehydrogenasesKrebs cycle? a)3 b)2 c)4 d)5 CorrectAnswer-CAns.is'c'i.e.,4
129.NumberofATPgeneratedinoneTCA cycle? a)2 b)8 c)10 d)11 CorrectAnswer-CAns.is'c'i.e.,10InasingleTCAcycle10moleculesofATPareproduced(12moleculesaccordingtooldercalculations).OneturnoftheTCAcycle,startingwithacetylCoAproduces10ATPs.Whenthestartingmoleculeispyruvate,theoxidativedecarboxylationofpyruvate,theoxidativedecarboxylationofpyruvateyields2.5ATPsandtherefore,12.5ATPsareproducedwhenstartingcompoundispyruvate.Since,twomoleculesofpyruvateentertheTCAcyclewhenglucoseismetabolized(glycolysisproduces2moleculesofpyruvate),thenumberofATPsisdoubled.Therefore,25ATPmolecules,perglucosemolecule,areproducedwhenpyruvateenterstheTCAcycle.Note:PreviouslycalculationsweremadeassumingthatNADHproduces3ATPsandFADHgenerates2ATPs.Thiswillamountanetgenerationof30ATPmoleculesinTCApermoleculeglucoseandtotal38moleculesfromstarting.RecentexperimentsshowthatthesevaluesareoverestimatesandNADHproduces2.5ATPsandFADHproduces1.5ATPs.Therefore,netgenerationduringTCAis25ATPsandcompleteoxidationofglucosethroughglycolysispluscitricacidcycleyieldanet32ATPs.Energyyield(numberofATPgenerated)permoleculeofglucose
whenitiscompletelyoxidizedthroughglycolysispluscitricacidcycle,underaerobicconditions,isasfollows:-
130.Ifurinesampledarkensonstanding:the mostlikelyconditionsis? a)Phenylketonuria b)Alkaptonuria c)Maplesyrupdisease d)Tyrosinemia CorrectAnswer-BAns.is'b'i.e.,AlkaptonuriaAlkaptonuriaItisduetodeficiencyofhomogentisateoxidase.Asaresulthomogentisicacid(homogentisate)isexcretedexecessivelyinurine.Therearcthreeimportantcharacteristicfeaturesinalkaptonuria?i)Urinebecomesdarkafterbeingexposedtoair.Itisduespontaneousoxidationofhomogentisateintobenzoquinoneacetate,whichpolymersetoformblack-brownpigmentalkaptonwhichimpartsacharacteristicblack-browncolourtourine.ii)Alkaptondepositionoccursinsclera,ear,nose,cheeksandintervertebraldiscspace.Aconditioncalledochronosis.Theremaybecalcificationofintervertebraldiscs.iii)Onchronosisarthritisaffectingshoulder,hips,knee.Benedict'stestisstronglypositiveinurineandsoistheferricchloride(FeC13)test.Benedict'sreagentgivesagreenishbrownprecipitatewithbrownishblacksupernatent.Fehling'sreagent(FeC13)givesbluegreencolour.
131.Whichofthefollowingenzymedoesnot catalyzesirreversiblestepinglycolysis? a)Hexokinase b)Phosphoglyceratekinase c)Pyruvatekinase d)Phosphofructokinase CorrectAnswer-BAns.is'b'i.e.,PhosphoglycoratekinaseGlycolysisisregulatedat3stepswhichareirreversible.Thesereactionsarecatalyzedbyfollowingkeyenzymes:?1)Hexokinaseandglucokinase2)Phosphofructokinase-I3)Pyruvatekinase.
132.Taurineismadefrom? a)Glycine b)Tyrosine c)Cysteine d)Phenylalanine CorrectAnswer-CAns.is'c'i.e.,CysteineTaurineissynthesizedfromcysteine.
133.Aminoacidcarryingammoniafrom muscletoliver? a)Alanine b)Glutamine c)Arginine d)Lysine CorrectAnswer-AAns.is'a'i.e.,Alanine.DISPOSAL/DETOXIFICATIONOFAMMONIA1.FirstlineofDefense(Trappingofammonia)Beinghighlytoxic,ammoniashouldbeeliminatedordetoxified,asandwhenitisformed.Evenveryminutequantityofammoniamayproducetoxicityincentralnervoussystem.But,ammoniaisalwaysproducedbyalmostallcells,includingneurons.Theintracellularammoniaisimmediatelytrappedbyglutamicacidtoformglutamine,especiallyinbraincells.Theglutamineisthentransportedtoliver,wherethereactionisreversedbytheenzymeglutaminase.Theammoniathusgeneratedisimmediatelydetoxifiedintourea.Asparticacidmayalsoundergosimilarreactiontoformasparagine.2.TransportationofAmmoniaInsidethecellsofalmostalltissues,thetransaminationofaminoacidsproduceglutamicacid.However,glutamatedehydrogenaseisavailableonlyintheliver.Therefore,thefinaldeaminationandproductionofammoniaistakingplaceintheliver.Thus,glutamicacidactsasthelinkbetweenaminogroupsofamino
acidsandammonia.Theconcentrationofglutamicacidinbloodis10timesmorethanotheraminoacids.Glutamineisthetransportformsofammoniafrombrainandintestinetoliver;whilealanineisthetransportformfrommuscle.3.FinaldisposalTheammoniafromalloverthebodythusreachesliver.Itisthendetoxifiedtoureabylivercells,andthenexcretedthroughkidneys.Ureaistheendproductofproteinmetabolism. Transportofalaninefrommuscletoliver(glucose-alaninecycle)hastwofunctions:?i)Providingsubstrateforgluconeogenesisii)Transportofammonia(NH4-)toliverforureasynthesis.
134.FIGLUexcretiontestisusedfor assessmentofdeficiencyof? a)VitaminB12 b)Niacin c)Folicacid d)Pyridoxin CorrectAnswer-CAns.is'c'i.e.,FolicacidAssessmentoffolatedeficiencyFollowingtestsarcusedforassessmentoffolatedeficiency.i)Bloodlevel:-Normallevelinserumisabout2-20nanogram/mlandabout200micorgram/mlofpackedcells.ii)HistidineloadtestorFIGLUexcretiontest:-Histidineisnormallymetabolizedtoformiminoglutamicacid(FIGLU)fromwhichformiminogroupisremovedbyTHF.Thereforeinfolatedeficiency,FIGLUexcretionisincreasedinurine.
135.RoleofmolecularoxygeninETC? a)TransferofreducingequivalenttoCoQ b)Transferofreducingequivalentfromcytosoltomitochondria c)Toactaslastelectronacceptor d)GenerationofATP CorrectAnswer-CAns.is'c'i.e.,ToactaslastelectronacceptorStructuralorganizationsofcomponentsofETC3Componentsofrespiratorychaindonotfunctionasdiscretecarriersofreducingequivalentbutareorganizedintofourcomplexeseachofwhichactsasaspecificoxidoreductase.CoenzymeQandcytochromeCarenotpartsofanycomplexandarenotfixedintheinnermitochondria!membrane.Theothercomponentsarefixedinthemembrane.Thesecomponentsarearrangedinorderofincreasingredoxpotential.Therefore,reducingequivalents(electrons)flowinonedirection,I--->II-->III-->IV,onlybecauseredoxcouplewithlowredoxpotentialisbetterelectrondonorwhereastheonewithhighredoxpotentialiselectronacceptor.Thus,reducingequivalents(electrons)flowthroughthechainfromthecomponentsofmorenegativeredoxpotentialtothecomponentsofmorepositiveredoxpotential.i)ComplexI(NADH-CoQreductase)catalyzesthetransferofelectronfromNADHtocoenzymeQ(CoQ).ii)ComplexII(Succinate-CoQreductaseorsuccinatedehydrogenase)transferselectronsfromsuccinatetocoenzymeQ.iii)ComplexIII(CoQ-cytochromeCreductase),transferselectronfromCoQtocytochromeC.iv)ComplexIV(cytochromeCoxidase)transferselectronsfromcytochromeCto02.
cytochromeCto02.
136.Whichofthefollowingisa homopolysaccharide? a)Heparin b)Chitin c)Hyaluronicacid d)Chondroitinsulfate CorrectAnswer-BAns.is'b'i.e.,ChitinPolysaccharidesareclassifiedinto?a)Homopolysaccharides(Homoglycans):-Thistypeofpolysaccharideismadeupofseveralunitsofsamemonosaccharideunitonly.Examplesarestarch(multipleunitsofglucose),glycogen(multipleunitsofglucose),cellulose(multipleunitsofglucose),Inulin(multipleunitoffructose),Dextrin,Dextran(multipleunitsofglucose),andchitin.b)Heteropolysaccharides(Heteroglycans):-Thistypeofpolysaccharidecontainstwoormoredifferenttypesofmonosacharideunits.Examplesareheparin,heparansulfate,chondroitinsulfate,dermatansulfate,hyaluronicacid,keratansulfateandbloodgrouppolysaccharides.
137.Iftyrosinelevelinbloodisnormal withoutexternalsupplementation,deficiencyofwhichofthefollowingisruledout? a)Tryptophan b)Phenylalanine c)Histidine d)Isoleucine CorrectAnswer-BAns.is'b'i.e.,PhenylalanineTyrosineissynthesizedfromphenylalanine.Inphenylalaninedeficiencyorindisordersinwhichphenylalaninecannotbeconvertedintotyrosine(phenylketonuria),tyrosinebecomesanessentialaminoacidandshouldbesupplementedfromoutside.
138.Endproductofporphyrinmetabolism? a)Albumin b)CO2&NH2 c)Bilirubin d)None CorrectAnswer-CAns.is'c'i.e.,BilirubinHemeisthemostimportantporphyrin.Itisdegradedintobilirubin.
139.Huntersyndromeisduetodeficiencyof a)Betagalactosidase b)Sphingomyelinase c)IduronateSulfatase d)Hyaluronidase CorrectAnswer-CAns.is'c'i.e.,IduronateSulfatase
140.UDPglucoseisnotusedin? a)Uronicacidpathway b)Glycogensynthesis c)Galactosemetabolism d)HMPshunt CorrectAnswer-DAns.is'd'i.e.,HMPshuntUDP-glucoseisderivedfromglucose-6-phosphateviaglucose-l-phosphate.ThemajorfateofUDP-glucoseisthesynthesisofglycogen.OtherusesofUDP-glucoseare-1.Inuronicacid(glucoronicacid)cycletogenerateUDPglucuronate.2.Galactosemetabolism3.Glycosylationofproteins,lipidsandproteoglycans.
141.NumberofATPmoleculesandNADH formedineachcycleofglycolysis? a)4ATP,2NADH b)2ATP,2NADH c)4ATP,4NADH d)2ATP,4NADH CorrectAnswer-AAns.is'a'i.e.,4ATP,2NADHEnegeticsofglvcolysisDuringglycolysis2ATPareutilizedand4ATPareproducedatsubstratelevel.2reducingequalentsNADH'areproducedandreoxidizedbyelectrontransportchain,togenerata5ATPmolecules(2.5ATPperNADH'molecule).Thustotal9ATPmoleculesareproducedand2areutilized,i.e.,Thereisnetgainof7ATPmoleculesinaerobicglycolysis.Inanaerobicconditions,thereoxidationofNADHbyelectrontransportchainispreventedandNADHgetsreoxidizedbyconversionofpyruvatetolactatebylactatedehydrogenase.Thus,inanaerobicglycolysisonly4ATPareproducedatsubstratelevel.Therefore,thereisnetgainof2ATPmoleculesinanaerobicglycolysis.Note:-PreviouscalculationsweremadeassumingthatNADHproduces3ATPsandFADH2generates2ATPs.Thiswillamounttoanetgenerationof8ATPsperglucosemoleculeduringglycolysis.RecentexperimentsshowthattheseoldvaluesareoverestimatesandNADHproduces2.5ATPsandFADH2produces1.5ATPs.Thus,netgenerationisonly7ATPsduringglycolysis.
142.Whichofthefollowingisnottrue regardingETC? a)Occursinmitochondria b)GeneratesATP c)Noroleofinorganicphosphate d)Involvestransportofreducingequivalent CorrectAnswer-CAns.is'c'i.e.,NoroleofinorganicphosphateInorganicphosphate(Pi)isrequiredinETCtogenerateATP.ADP+pi-->ATPETCoccursinmitochondriaandinvolvestransferofreducingequivalenttogenerateATP
143.Proteinsareseparatedonthebasisof chargein? a)SDS-PAGE b)Ultracentrifugation c)Affinitychromatography d)HPLC CorrectAnswer-DAns.is'd'i.e.,HPLC
144.IsoformofLDHinskeletalmuscles? a)LDH-1 b)LDH-2 c)LDH-3 d)LDH-4 CorrectAnswer-DAns.is'd'i.e.,LDH-4SkeletalmusclescontainLDH-4andLDH-5
145.Followingistrueregardingsulhydryl groupsexcept? a)TheyarepresentincoenzymeAandlipoicacid b)TheyarepresentinCaptoprilandpenicillamine c)Theyarenotinvolvedinreductionofperoxides d)Theyarepresentincysteine CorrectAnswer-CAns.is'c'i.e.,TheyarenotinvolvedinreductionofperoxidesSulfhydrylGroup(orthiolgroup)ItisanSHgroupoforganiccompounds.Sulfhydrylgroupshavegreatandvariedreactivity.Theyoxidizeeasily,withtheformationofdisulfidesandsulfenic,sulfinic,orsulfonicacids,andtheyreadilyundergoalkylation,acylation,andthiol-disulfideexchange.Theyformmercaptidesuponreactingwiththeionsofheavymetals,andtheyformmercaptalsandmercaptolsuponreactingwithaldehydesandketones,respectively.Sulfhydrylgroupsplayanimportantroleinbiochemicalprocesses.ThesulfhydrylgroupsofcoenzymeA,lipoicacid,and4'-phosphopantotheineparticipateinenzymaticreactionsfortheformationandtransferofacylresiduesthatarerelatedtolipidandcarbohydratemetabolism.Thesulfhydrylgroupsofglutathioneplayanimportantroleintheneutralizationofforeignorganiccompoundsandthereductionofperoxides;theyarealsoofmajorimportanceinthefulfillmentbyglutathioneofitsfunctionasacoenzyme.Inproteins,residuesoftheaminoacidcysteinehavesulfhydrylgroups.
Ascomponentsoftheactivecentersofanumberofenzymes,sulfhydrylgroupsparticipateinthecatalyticeffectoftheenzymesandinthebindingofsubstrates,coenzymes,andmetalions.Drugscontainingsulfhydrylgroupsare:captopril,zofenoprilandpenicillamine.
146.CauseofHerpesZoster? a)PrimaryinfectionwithVZV b)RecurrentinfectionwithVZV c)ReactivationoflatentinfectionofVZV d)MultipleinfectionwithVZV CorrectAnswer-CAns.is'c'i.e.,ReactivationoflatentinfectionofVZVVaricellazostervirusinfectionVaricella(Chickenpox)andHerpeszosteraredifferentmanifestationsofthesamevirusinfection.Thevirusisthereforecalledvaricellazostervirus(VZA)PrimaryinfectionwithVZVcauseschickenpox.ReactivationoflatentVZV,whenimmunityhasfallentoineffectivelevelscauses-HerpeszosterThevirusremainsdormantinsensoryganglionoftrigeminalnerveandreachestheeyealongoneormorebranchesoftheopthalmicdivisionofthe5thnerveHerpesZoster(Shingles)Occursinoldage60yearsoraboveAsaconsequenceofreactivationoflatentinfectionfromthedorsalrootganglion.oUnilateralvesiculareruptionswithinadermatomaldistributionDermatomesfromT3toL3andtrigeminalnerve(especiallyophthalmicbranch)areinvolved.oZosterophthalmicus-duetoreactivationinophthalmicbranchoftrigeminal(gasserian)gangliaoRamsayHuntSyndrome-duetoreactivationingeniculateganglionoffacialnerve.oComplicationsPostherpeticneuralgia-mostdebilitatingcomplication
1. Meningealirritation2. Transversemyelitis3. Cutaneousdissemination4. Patient'swithhodgkin'sdiseaseandnonhodgkin'slymphomaareat greatestriskforprogressivehespeszoster. 5. Bacterialsuperinfection
147.Bileacidsaresynthesizedfrom? a)Heme b)Cholesterol c)Ribulose d)Arachidonicacid CorrectAnswer-BAns.is'b'i.e.,CholesterolPrimarybileacidsarecholicacidandchenodeoxycholicacid,whicharesynthesizedfromcholesterolinliver.Intheintestinesomeoftheprimarybileacidsareconvertedintosecondarybileacids,i.e.,deoxycholicacid(formedfromcholicacid)andlithocholicacid(derivedfromchenodexoxycholicacid).Glycineandtaurineconjugatesofthesebileacidsarecalledasbilesalts.Forexample,cholicacidisabileacid,anditsglycineconjugate(glycocholicacid)isabilesalt.Bilesaltshelpindigestionandabsorptionoffatbyemulsificationandmicellesformation.Bilesaltsactasdetergents,i.e.,theyhavesurfacetensionloweringaction.Detergentactionisduetoamphipathicnatureofbilesalts(Note:Amphipathicmoleculesaremoleculesthatcontainbothhydrophobicnon-polaraswellashydrophilic-polarends).
148.Notasubstrateforgluconeogenesis- a)Glycerol b)Leucine c)Lactate d)Propionate CorrectAnswer-BAns.is'b'i.e.,LeucineSubstratesforgluconeognesis? 1. Lactate2. Allaminoacidsexceptleucineandlysine3. Pyruvate4. Propionate5. Glycerol6. Intermediatesofcitricacidcycle Alanineisthemostimportantgluconeogenicaminoacid.
149.Ratelimitingenzymeinbileacid synthesis? a)Desmolase b)21-hydroxylase c)7-hydroxylase d)12-hydroxylase CorrectAnswer-CAns.is'c'i.e.,7-hydroxylaseAbouthalfofthecholesterolinthebodyisultimatelymetabolizedtobileacids.Theprimarybileacidsaresynthesizedfromcholesterolinliver.Thesearecholicacidandchenodeoxycholicacid.Ratelimitingenzymeinprimarybileacidssynthesisis7-hydroxylase(cholesterol7-hydroxylase).Thisenzymeisinhibitedbybileacidsandinducedbycholesterol.Thyroidhormonesinducetranscriptionof7a-hydroxylase,thusinpatientswithhypothyroidismplasmacholesteroltendstorise(becauseofinhibitionof7-hydroxylasewhichinturninhibitsconversionofcholesteroltobileacids).
150.Ratelimitingenzymeincatecholamine synthesis? a)Dopadecarboxylase b)N-methyltransferase c)Dopaminehydroxylase d)Tyrosinehydroxylase CorrectAnswer-DAns.is'd'i.e.,Tyrosinehydroxylase
151.NAD+Actsasacoenzymefor? a)Xanthineoxidase b)L-aminoacidoxidase c)Succinatedehydrogenase d)Malatedehydrogenase CorrectAnswer-DAns.'D'MalatedehydrogenaseNAD-linkeddehydrogenasesPyruvatedehydrogenase,isocitratedehydrogenase,malatedehydrogenase,a-ketoglutaratedehydrogenase,glutamatedehydrogenase,glyceraldehyde-3-Pdehydrogenase,lactatedehydrogenase,13-hydroxyacylCoAdehydrogenase,glycerol3-Pdehydrogenase(cytoplasmic).NADP*-linkeddehydrogenasesGlucose-6-Pdehydrogenase,6-Phosphogluconatedehydrogenase,3-ketoacylreductase,Enoylreductase,gulonatedehydrogenase.FAD-linkeddehydrogenasesSuccinatedehydrogenase,fattyacylCoAdehydrogenase,glycerol-3Pdehydrogenase(mitochondrial).
152.TrueabouttRNA? a)80%oftotalRNA b)Contains50-60nucleotides c)CCAsequenceistranscribed d)LongestRNA CorrectAnswer-C"TheCCAtailisaCCAsequenceat3'endofthetRNAmolecule.Inprokaryotes,CCAsequenceistranscribed.Ineukaryotes,theCCAsequenceisaddedduringprocessing"."tRNAisthesmallestofthreemajorspeciesofRNAs"--DineshpuritRNAcomprises15%oftotalRNAinthecell.Itcontains73-93nucleotideresidue.
153.Selenocysteineisassociatedwith? a)Carbonicanhydrase b)Catalase c)Deiodinase d)Transferase CorrectAnswer-CAns.C.DeiodinaseSelenocysteineisconsideredas21standardaminoacid.Itispresentattheactivesiteofsomeenzymesthatcatalyzeredoxreactions,e.g.thioredoxinreductase,glutathioneperoxidase,andthedeiodinase(convertsthyroxintotriiodothyronine).Biosynthesisofselenocysteinerequirescysteine,serine,ATPandaspecifict-RNA.Serineprovidesthecarbonskeletonofselenocysteine.Selenocysteinehasastructuresimilartocysteine,butcontainingthetraceelementseleniuminplaceofsulfuratomofcysteine.
154.Whichvitaminisrequiredfortransferof 1-carbonunit? a)VitaminA b)Folicacid c)VitaminB12 d)Niacin CorrectAnswer-BFolicacid[RefHarper29m/ep.537-539,Vasudevanelep.400-402]Goups,containingasinglecarbonatomarecalledonecarbongroups.Onecarbongroupsareformedfromfollowingaminoacidsduringtheirmetabolism:-Serine,glycine,histidineandtryptophan.Onecarbongroupsformedduringmetabolismare:methyl(C113),methylene(CH,),methenyl(CH),formyl(CHO)andformimino(CH=NH)Theseonecarbongroupsaretransferredbywayoftetrahydrofolate(THF),whichisderivativeoffolicacid?.OnecarbongroupscarriedbyTHFareattachedeithertonitrogenN5orMc'ortobothN5andN").DifferentonecorbonderivativesofTHFare-N5-methylTHF,N5,N'?-methyleneTHF,N5,N"-methenylTHF,N5-formylTHFandN5-formiminoTHEThesederivativesareinterconvertable.
155.Hemeissynthesizedfrom? a)Lysine+succinylCoA b)Glycine+succinylCoA c)Arginine+MalonylCoA d)Glycine+MalonylCoA CorrectAnswer-BAns.B.Glycine+succinylCoAOrganelle:PartlycytoplasmicandpartlymitochondrialStartingmaterials:SuccinylCoAandGlycine
156.Splicingisaprocessof? a)Activationofprotein b)Removalofintrons c)Synthesisofprotein d)ReplicationofDNA CorrectAnswer-BInmolecularbiologyandgenetics,splicingisamodificationofanRNAaftertranscription,inwhichintronsareremovedandexonsarejoined.ThisisneededforthetypicaleukaryoticmessengerRNAbeforeitcanbeusedtoproduceacorrectproteinthroughtranslation.Formanyeukaryoticintrons,splicingisdoneinaseriesofreactionswhicharecatalyzedbythespliceosomeacomplexofsmallnuclearribonucleoproteins(snRNAs),buttherearealsoself-splicingintrons.
157.Creatinineisformedfrom- a)Glycine b)Lysine c)Leucine d)Histamine CorrectAnswer-AAns.A.GlycineCreatinineandcreatinearesynthesizedfromglycine,arginine,andmethionine.SynthesisofcreatineandcreatinineCreatineandcreatininearenotaminoacids,butspecializedproductsofaminoacids.Creatineissynthesizedfromglycine,arginine,andmethionine.Thesynthesisstartswiththeformationofguanidinoacetatefromglycineandarginineinthekidney.Furtherreactionstakeplaceintheliverandmuscle.
158.MostcommonlyusedvectorforDNA cloning? a)Plasmid b)Virus c)Cosmid d)Phage CorrectAnswer-AAns:A.PlasmidAcloningvectorisacarrierDNAmoleculetowhichhumanDNAfragmentisattached.Normally,foreignDNAfragmentscannotself-replicatewithinhostcell.Therefore,theyarejoinedtoavectorDNA,thatcanreplicatewithinhostcell.Thefivemajortypesofcloningvectorsusedare-*Plasmids*Viralvectors/Bacteriophages*Cosmids*BacterialArtificialChromosomes(BACs)*Yeastartificialchromosomes(YACs)
159.RichestsourceofvitaminB12? a)Meat b)Greenleafyvegetables c)Cornoil d)Sunfloweroil CorrectAnswer-AAns.is'a'i.e.,MeatVitaminB12isnaturallyfoundinanimalproducts,includingfish,meat,poultry,eggs,milk,andmilkproducts.VitaminB12isgenerallynotpresentinplantfoods,butfortifiedbreakfastcerealsareareadilyavailablesourceofvitaminB12withhighbioavailabilityforvegetarians.RichsourceofvitaminB12Beef,liver,andchicken.Fishandshellfishsuchastrout,salmon,tunafish,andclams.Fortifiedbreakfastcereal.Low-fatmilk,yogurt,andcheese.Eggs.
160.Keshandiseaseinduetodeficiencyof a)Selenium b)Copper c)Zinc d)Iron CorrectAnswer-AAns.'a'SeleniumSeleniumisrequiredforthesynthesisoftheaminoacidselenocysteine.Selenocysteineispresentattheactivesiteofseveralhumanenzymesthatcatalyzeredoxreactions.Impairmentsinhumanselenoproteinshavebeenimplicatedintumorigenesisandatherosclerosis,andareassociatedwithseleniumdeficiencycardiomyopathy(Keshandisease)
161.PFK-Iinhibitor? a)AMP b)Citrate c)Glucose6phosphate d)Insulin CorrectAnswer-BAns.is'b'i.e.,Citrate
162.Allareusedingluconeogenesisexcept? a)Oleate b)Succinate c)Glutamate d)Aspartate CorrectAnswer-AAns.is'a'i.e.,OleateSubstrateofgluconeogenesisare:Lactate(lacticacid)PyruvateAllaminoacids(exceptleucineandlysine)PropionateIntermediatesofcitricacidcycleFattyacidsarenotsubstratesforgluconeogenesis.ComingtothequestionFattyacids(oleateinthequestion)isnotasubstrateforgluconeogenesis.SuccinateisanintermediateofTCAcycle,andisasubstrateforgluconeogenesis.Allaminoacids(inthequestionglutamateandaspartate),exceptleucineandlysinearesubstratesforgluconeogenesis.
163.Mainenzymeforglycogenmetabolism? a)Glucose-6-phosphatase b)Glycogensynthase c)PFK-1 d)Noneoftheabove CorrectAnswer-BAns.is'b'i.e.,Glycogensynthase
164.Actionofmetalloproteinase? a)Degradationofcollagen b)Polymerizationofcollagen c)Oxidationofcollagen d)Stimulationofcollagen CorrectAnswer-AAns.is'a'i.e.,DegradationofcollagenDegradationofcollagenandotherECM(extracellularmatrix)proteinsisachievedbymatrixmetalloproteinases(MMPs).MMPsisafamilyofenzymesthathaveincommona180-residuezincproteasedomain.Matrixmetalloproteinasesinclude:-Interstitialcollagenase(MMP-1,2,and3):CleavethefibrillarcollagentypesI,IIandIII.Gelatinases(MMP-2and9):Degradeamorphouscollagenandfibronectin.Stromelysins(MMP-3,10and11):Actonproteoglycans,laminin,fibronectinandamorphouscollagen.Membrane-boundMMPs(ADAMs):Cleavemembrane-boundprecursorformsofTNFandTGF-a,releasingtheactivemolecule.
165.Proteincatabolismisincreasedin? a)Starvation b)Burns c)Surgery d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,AlloftheaboveConditionscausingincreasedproteincatabolismMultipletraumaInfectionandsepsisBurnsFeverSurgeryLongbonefractureProlongedstarvationProlongedcorticosteroidtherapy
166.TATAboxisseenin? a)Promoterregion b)Palindromicregion c)Enhancerregion d)Silencerregion CorrectAnswer-AAns.is'a'i.e.,Promoterregion
167.Frameshiftmutationdoesnoteffect completeaminoacidsequenceifitoccursinmultipleof? a)I b)2 c)3 d)None CorrectAnswer-CAns.is'c'i.e.,3Frame-shiftmutationFrameshiftmutationsQoccurduetoinsertionordeletionQofoneortwobaseswhichcauseschangeinthereadingframedistaltothemutation.IfIor2basepairchange,wholereadingframeischangeddistaltothemutation,resultingintoentirelydifferentproteinmolecule.If3basepairschange,singleaminoacidisincorporatedordeleted.Therestofaminoacidsequenceissame.Thisisbecausethegeneticcodeisreadinformoftripletsofnucleotides(i.e.codons).Ifoneortwobasepairsfromthecodeareremovedorinserted,thegeneticcodewillbemisreadfromthatchangeonwardsbecausegeneticcodeisnotpunctate.Thereforetheaminoacidsequencetranslatedfromthechangeonwardswillbecompletelychanged.Howeveriftheremoval/insertionhappensinmultipleofthree,restofthereadingfromdoesnotchangeandhencetheaminoacidsequencewillnotchange.
168.Corisdiseaseisduetodefectin a)Branchingenzyme b)Debranchingenzyme c)Myophosphorylase d)Hepaticphosphorylase CorrectAnswer-BAns.is'b'i.e.,Debranchingenzyme Organ(s) Type Enzymedeficiency affectedGlucose6- I vonGierke'sdisease Liver,kidney phosphatasea(1?44) II Pompe'sdisease Allorgans Glucosidase (acidmaltase) Cori's Debranching disease/Forbe's Muscle,liver enzyme III disease Liver, IV Andersen'sdisease Branchingenzyme myocardium V McArdle'sdisease Phosphorylase Muscle VI Hers'disease Phosphorylase Liver VII Tarui'sdisease Phosphofructokinase Muscle,RBCsPhosphorylase Liver VIII kinase ThereisalsoonX-linkedformofphosphorylasekinasedeficiency.Thisissoleexceptionasallotherglycogenstoragediseasesareinheritedasautosomalrecessivetrait.
169.Oxidativedeaminationiscatalyzedby? a)Glutaminase b)Glutaminesynthase c)Glutamatedehydrogenase d)Noneoftheabove CorrectAnswer-CAns.is'c'i.e.,Glutamatedehydrogenase
170.Glucoseistransportedinpancreas throughwhichreceptor? a)GLUT1 b)GLUT2 c)GLUT3 d)GLUT4 CorrectAnswer-BAns.is'b'i.e.,GLUT2GlucoseenterstheBcellsofpancreaticisletsviaGLUT2transporterandthisstimulatethereleaseofinsulin.
171.Immediatesourceofenergyis? a)Cori'scycle b)HMP c)ATP d)TCAcycle CorrectAnswer-CAns.is'c'i.e.,ATPTherearethreeenergysystemstoprovideenergyformuscularactivities.Immediateenergysystem:EnergyisprovidedbystoredATPandcreatinephosphate.Anaerobicglycolyticsystem(lacticacidsystem):Energyisgeneratedbyutilizationofglucoseorglycogenbyanaerobicglycolysis.Thisenergyisalsogeneratedearly.Aerobicoroxidativesystem:Energyisgeneratedbyutilizationofglucose/glycogen,andfattyacidsthroughoxidativepathways,e.g.TCAcycle.Thesethreeenergysystemsoperateasacontinuum;eachsystemisalwaysfunctioning,evenatrest.oWhatvariesistherelativecontributioneachsystemmakestototalATPproductionatanygiventime. Oxidative(aerobic) Immediate Anerobic system energysystem glycolyticsystem Glucoseor ATP,creatine Glucoseor glycogen,fatty phosphate glycogen Substrates acids EnergyproductionVery Fast Slow fastPeakat 0-30sec. 20-180sec. >3min
Peakat 0-30sec. 20-180sec. >3min Limiting DepletionofCrP, Lacticacidas_. Glycogendepletion factor ATP vitiation Activity Powerlifting& Longersprints Enduranceevents example weightlifting,short Middledistance Teamsports sprints teamsports Jumping, Ballgames Ballgames(Soccer, throwing (Soccer,rugby) fieldhockey)
172.Whichofthefollowingvitaminsdoesnot participateinoxidativedecarboxylationofpyruvatetoacetylCoA? a)Thiamine b)Niacine c)Riboflavin d)Biotin CorrectAnswer-DAns.is`d'i.e.,Biotin
173.Salvagepathwayofpurinenucleotide synthesisareusedbyallexcept? a)Brain b)Liver c)RBC d)Leukocytes CorrectAnswer-BAns.is'b'i.e.,LiverPurinenucleotidesynthesisoccursbytwopathways:DenovosynthesisSalvagepathwayLiveristhemajorsiteofpurinenucleotidebiosynthesis(denovo).Certaintissuescannotsynthesizepurinenucleotidesbydenovopatyway,eg.brain,erythrocytesandpolymorphonuclearleukocytes.Thesearedependentonsalvagepathwayforsynthesisofpurinenucleotidesbyusingexogenouspurines,whichareformedbydegradationofpurinenucleotidessynthesizedinliver.
174.Carboxypeptidasecontainswhich mineral? a)Copper b)Zinc c)Iron d)None CorrectAnswer-BAns.is'b'i.e.,ZincZinccontainingenzymesarecarboxypeptidase,carbonicanhydrase,alkalinephosphatase,lactatedehydrogenase,alcoholdehydrogenase,glutamatedehydrogenase,RNApolymeraseandsuperoxidedismutase.
175.Krabbesdiseaseisduetodeficiencyof? a)Sphingomyelinase b)Betagalactocerebrosidase c)Hexosaminidase d)Arylsulfatase CorrectAnswer-BAns.is'b'i.e.,Betagalactocerebrosidase
176.Trueaboutgluconeogenesis? a)Occursmainlyinmuscle b)Itisreverseofglycolysis c)Alanine&lactatebothcanserveassubstrate d)Glycerolisnotasubstrate CorrectAnswer-CAns.is'c'i.e.,Alanine&lactatebothcanserveassubstrateSynthesisofglucosefromnoncarbohydrateprecursorsiscalledgluconeogenesisi.e.,synthesisofnewglucose.Themajornoncarbohydrateprecursors(substrate)forgluconeogenesisarelactate,pyruvate,glycerol,glucogenicaminoacids,propionateandintermediatesofthecitricacidcycle.Allaminoacids,exceptforleucineandlysine,aresubstrateforgluconeogenesis.Alanineisthemostimportantgluconeogenicaminoacid.Gluconeogenesisoccursmainlyintheliverandtoalesserextentinrenalcortex.Somegluconeogenesiscanalsooccurinsmallintestine,butitisnotsignificant.Someofthereactionsofgluconeogenesisoccursinthemitochondriabutmostoccurincytosol.Gluconeogenesisinvolvesglycolysis,thecitricacidcycleplussomespecialreactions.Glycolysisandgluconeogenesissharethesamepathwaybutinoppositedirection.Sevenreactionsofglycolysisarereversibleandthereforeareusedwithsameenzymeinthesynthesisofglucosebygluconeogenesis.However,threeofthereactionsofglycolysisareirreversibleand
mustbecircumventedbyfourspecialreactionswhichareuniquetogluconeogenesisandcatalyzedby:(1)Pyruvatecarboxylase,(ii)Phosphoenolpyruvatecarboxykinase,(iii)Fructose-1,6-bisphosphatase,(iv)Glucose-6-phosphatase.Thesefourenzymesarethekeyenzymesofgluconeogenesis(orgluconeogenesisenzymes).Amongthesefour,pyruvatecarboxylaseisamitocondrialenzymeandotherthreearecytoplasmicenzymes.
177.Whichenzymepolymerisesokazaki fragments? a)DNApolymeraseI b)DNApolymeraseII c)DNApolymeraseIII d)RNApolymerase CorrectAnswer-CAns.is'c'i.e.,DNApolymeraseIIITwoDNApolymerasesactonOkazakifragments:?DNApolymerase:-Causespolymerizationofokazakifragments,i.e.synthesisofDNAonlaggingstrand.Italsocausessynthesisofleadingstrand.DNApolymeraseI:-Itfillsthegapbetweenokazakifragmentswhentheirpolymerizationiscompleted,i.e.whenthesynthesisonlaggingstrandiscompleted,DNApolymeraseIfillsthegapbetweenfullypolymerizedokazakifragments.Thus,DNApolymeraseIIIisinvolvedduring'elongation'(polymerizationofokazakifragments)andDNApolymeraseIisinvolvedduring'termination'(fillingthegapsbetweenokazakifragments).
178.Riboflavindeficiencyisassessedby? a)Transketolase b)Glutathionereductase c)PDH d)None CorrectAnswer-BAns.is'b'i.e.,GlutathionereductaseRiboflavin(VitaminB2)RiboflavinisalsocalledWarburgyellowenzyme.Riboflavinprovidesthereactivemoietiesofthecoenzymesflavinmononucleotide(FMN)andflavinadeninedinucleotide(FAD).Flavincoenzymesareinvolvedinoxidoreductionreactionsaselectroncarriers.Thesereactionsincludethemitochondrialrespiratorychain,keyenzymesinfattyacidandaminoacidoxidationandthecitricacidcycle.Flavindependent(flavoprotein)enzymesare:FMNdependent:L-aminoacidoxidase,NADHdehydrogenase.FADdependent:ComplexIIofrespiratorychain,microsomalhydroxylasesystem,D-aminoacidoxidase,xanthineoxidase,succinatedehydrogenase,acyl-CoAdehydrogenase,glycerol-3-phosphatedehydrognenase,pyruvatedehydrognenase,a-ketoglutaratedehydrogenase.Deficiencyofriboflavinischarcterizedbycheilosis,desquamationandinflammationoftongue,andaseborrheicdermatitis.RiboflavinnutritionalstatusisassessedbymeasurementofactivationofglutathionereductasebyFADaddedinvitro.
179.Hemeiswhichporphyrin? a)TypeI b)TypeII c)TypeIII d)TypeIV CorrectAnswer-CAns.is'c'i.e.,TypeIII
180.Whichofthefollowingisalyase? a)Decarboxylase b)Synthetase c)Kinase d)Oxygenase CorrectAnswer-AAns.is'a'i.e.,Decarboxylase Enzymeclass Importantenzymes Oxidases,Dehydrogenases,Hydroperoxidases, Oxidoreductase (catalase,peroxidase),oxygenases Aminotransferaseortransaminase,e.g.,SGOT(AST)andSGPT(ALT),kinases(Hexokinaseo Transferase glucokinase,pyruvatekinaseetc),Transketolases,transaldolases,transcarboxylaseAlldigestiveenzymes(Pepsin,trypsin,lipases, Hydrolases esterases),lysosomalenzymes,urease,andphosphataseDecarboxylasesQ,aldolases,hydratases,enolase, Lyases fumaraseQ,ArginosuccinaseRacemases,epimerases,cis-trans-isomerases, lsomerases mutases Ligases SynthatasesQ,Carboxylases,DNAligase
181.NotpresentinDNA? a)Uracil b)Thymine c)Cytosine d)Adenine CorrectAnswer-AAns.is'a'i.e.,UracilTwotypesofbasesarefoundinnucleotides:(i)purinesand(ii)pyrimidines. 1. Purines:TwomajorpurinebasesfoundbothinDNAsaswellas RNAsare(i)adenine(A)and(ii)guanine(G). 2. Pyrimidines:Threemajorpyrimidinebasesare(i)cytosine(C),(ii) Uracil(U)and(iii)Thymine(T).CytosineanduracilarefoundinRNAsandcytosineandthyminearefoundinDNAs.UracilisnotfoundinDNAseandthymineisnotfoundinRNAs.Differentmajorbaseswiththeircorrespondingnucleosidesandnucleotides Base Ribonucleoside Ribonucleotide Adenine Adenosinemonophosphate Adenosine (A) (AMP) Guanine Guanosinemonophosphate Guanosine (G) (GMP) Uracil(U) Uridine Uridinemonophosphate(UMP) Cytosine Cytidine Cytidine(Monophosphate)(CMP) (C)Base Deoxyribonucleoside Deoxyribonucleotide Deoxyadenosinemonophosphate Deoxyadenosine
Deoxyadenosine Adenine (dAMP) Deoxyguanosinemonphosphate Guanine Deoxyguanosine (dGMP)Deoxycytidinemonophosphate Cytosine Deoxycytidine (dCMP)Deoxythymidinemonophosphate Thymine Deoxythymidine (dCMP)
182.Neutralaminoacidis? a)Aspartate b)Arginine c)Glycine d)Histidine CorrectAnswer-CAns.is'c'i.e.,GlycineNeutralaminoacidsAlanineAspargingCysteineGlycineGlutamineIsoleucineLeucineMethionineProlinePhenylalanineSerineThreonineTyrosineTryptophanValine
183.Allaretrueaboutketonebodiesexcept? a)Acetoacetateisprimaryketonebody b)Synthesizedinmitochondria c)Synthesizedinliver d)HMGCoAreductaseistherate-limitingenzyme CorrectAnswer-DAns.is'd'i.e.,HMGCoAreductaseistherate-limitingenzyme
184.ThemineralhavingactionlikevitaminE ? a)Calcium b)Iron c)Selenium d)Magnesium CorrectAnswer-CAns.is'c'i.e.,SeleniumSeleniumfunctionsasanantioxidantalongwithvitaminE.Seleniumisaconstituentofglutathioneperoxidase,anantioxidantenzymewhichpreventsagainstoxidativedamage.Seleniumalsoisaconstituentofiodothyroninedeiodinase,theenzymethatconvertsthyroxinetriiodothyronine.
185.Whichisanabnormallipoprotein? a)VLDL b)Chylomicron c)Lp(a) d)LDL CorrectAnswer-CAns.is'c'i.e.,Lp(a)SomepeoplehaveaspecialtypeofabnormalLDLcalledlipoprotein(a)orLp(a),containinganadditionalprotein,apoprotein-a.ElevatedLPalevelsareassociatedwithanincreasedriskofCHD.
186.Okazakifragmentsareformedduring? a)Transcription b)Translation c)DNAreplication d)None CorrectAnswer-CAns.is'c'i.e.,DNAreplication
187.Hay'ssulphertestisusedtodetect whichofthefollowing? a)Bilesaltsinurine b)Reducingsugarinurine c)Ketonebodiesinurine d)Urobilinogeninurine CorrectAnswer-AAns.is'a'i.e.,Bilesaltsinurine Tests Usedfor Rothera'stest Ketonebodiesinurine:-acetoneand (nitroprussidetest) acetocetate Gerhardt'stest(ferric Ketonebodiesinurine:-acetoacetate. chloridetest)Benedict'stest Reducingsugarsinurine Fehling'stest Reducingsugarsinurine Hay'ssulphertest Bilesaltsinurine Fouchet's(boriumsulphate Bilepigment:bilirubin test)Gmelin's(nitricacid)test Bilepigment:bilirubin VandenBerghtest Bilepigment:bilirubinBilinogens(stercobilinogen, Ehrlich'stest urobilinogen) Schlesinger'stest Bilins(stercobilin,urobilin).Porphobilinogenandurobilinogenin Ehrlich'saldehydetest urine
188.Whichofthefollowingaccumulatesin maplesyrupurinedisease a)Leucine b)Valine c)Isoleucine d)All CorrectAnswer-DAns.is`d'i.e.,AllMaplesyrupurinedisease(MSUD)orbranched-chainketoaciduria*Itisaninbornerrorofmetabolismofbranched-chainaminoacidsvaline,leucineandisoleucine.*Itisduetodeficiencyofanenzymethatcatalyzesthesecondreactionintheseaminoacidsmetabolismi.e.branchedchain-aketoaciddehydrogenasewhichcatalyzesthedecarboxylationofbranched-chainaminoacids.*Asaresult,thebranched-chainaminoacids,leucine,isoleucineandvaline,andtheira-ketoacidsaccumulateintheblood,urine,andCSF.*Thereisacharacteristicmaplesyrupodourtotheurine.*Inmaplesyrupurinediseasethereistheexcretionofbranched-chainaminoacids(isoleucine,leucine,valine)andtheirketoacids(-keto-methylvalerate,-ketoisocaproate,-ketoisovalerate)intheurine.
189.Keratinisa? a)Globularprotein b)Cylindricalprotein c)Fibrousprotein d)Noneoftheabove CorrectAnswer-CAns.is'c'i.e.,FibrousproteinBasedontheirthree-dimensionalshape(i.e.,conformation),theproteinsaredividedintotwoclasses: 1. Fibrousproteins:-Thepolypeptidechainsextendalonga longitudinalaxiswithoutshowinganysharpbends,givingthemrodorneedlelikeelongatedshape.Mostofthestructuralproteinsarefibrousproteins,e.g.,collagen,elastin,andkeratin.Fibrousproteinscentrifugemorerapidlybecauseoftheirrodlikeshape. 2. Globularproteins:-Thepolypeptidechainsaretightlyfoldedand packedintocompactstructuregivingsphericalorovalshape.Mostenzymes,tranportproteins(albumin,globulins),hemoglobin,myoglobin,antibodiesandhormonesareglobularproteins.
190.Keratincontains? a)Arginine b)Histidine c)Lysine d)All CorrectAnswer-DAns.is'd'i.e.,AllAminoacidsrequiredforspecializedproductsCreatineGlycine+Arginine+MethionineGlutathioneGlycine+Cysteine+GlutamateCystineCysteine+CysteinePurineGlycine+Aspartate+Glutamate+SerinePyrinidineAsparatate+GlutamineCarnosine13-Alanine+histidineCholineFormedwiththehelpofmethionine,glycine,serine,B6NitricoxideArginineHemeGlycinc,SuccinylCoACarnitineMethionine+lysineKeratinHistidine;arginine;lysine(1:12:4)GlutamateGamma-aminobutyricacid(GABA)
191.Whichofthefollowingishighenergy compound? a)ADP b)Glucose-6-phosphate c)Creatinephosphate d)Fructose-6-phosphate CorrectAnswer-CAns.is'c'i.e.,CreatinephosphateHighenergycompoundsTheenergyreleasedduringoxidationofmonosaccharides,fattyacidsandaminoacidsmaynotberequiredimmediately.Therefore,theremustbesomewayofstoringenergy.Theenergyreleasedduringcatabolismiscapturedintheformofagroupofcompoundsknownas"high-energyphosphates".ThemostimportantmemberofthisgroupisATP.Acompoundthatliberates7Kcal/molormoreonhydrolysisiscalledhighenergycompound,oracompoundthatonhydrolysisundergoesalarge(7kcal/mol)decreaseinfreeenergy(AG)understandardconditioniscalledhighenergycompound,i.e.,AG?-7Kcal/mol.Forexample,ATPliberates7.3Kcal/molonhydrolysis.Highenergycompoundsare:?Phosphatecompounds:Nucleotides(ATPQ,GTP,UTP,UDP-glucose),Creatininephosphate,argininephosphate,1,3-bisphosphoglycerate,Phosphoenolpyruvate,inorganicpyrophosphate,Carbamoylphosphatee,aminoacyladenylate(aminoacylAMP).Sulfurcompounds:-CoAderivatives(acetylCoAe,SuccinylCoA,
fattyacylCoA,HMGCoA),S-adenosylmethionine(SAM),adenosinephosphosulfate.Acompoundwhichliberates<7Kcal/molonhydrolysisiscalledlowenergycompound,i.e.,adecreaseinfreeenergyis<7Kcal/mol,i.e.,AG<-7Kcal/mol.Lowenergycompoundsareglucose-1-phosphate,fructose-6phosphate,glucose-6-phosphate,glycerol-3-phosphate,AMP,ADPQ.
192.Truestatementabouthemoglobinis? a)Eachhemoglobinmoleculeismadeof4polypeptidesofeach subunit b)Twoalphaandtwobetasubunitshavinga02attachedtoeach subunit c)Eachhemoglobinmoleculebindstoonlyone02molecule d)Eachhemoglobinhasonehememolecule CorrectAnswer-AAns.is'a'i.e.,Eachhemoglobinmoleculeismadeof4polypeptidesofeachsubunit
193.AllaretrueaboutLDLexcept? a)Moredensethanchylomicron b)SmallerthanVLDL c)Transportsmaximumamountoflipid d)Containsmaximumcholesterol CorrectAnswer-CAns.is'c'i.e.,Transportsmaximumamountoflipid
194. Gluconeogenesisfromlactateneedsall except? a)Transportoflactatefrommuscletoliver b)Conversionoflactatetopyruvate c)Transaminationofpyruvatetoalanine d)Noneoftheabove CorrectAnswer-CAns.is'c'i.e.,Transaminationofpyruvatetoalanine
195.AllaretrueaboutVitaminB12,except? a)Activeformismethylcobalamine b)Requiresforconversionofhomocysteinetomethionine c)RequiresinmetabolismofmethylmalonylCoA d)Requiresforconversionofpyruvatetolactate CorrectAnswer-DAns.is'd'i.e.,Requiresforconversionofpyruvatetolactate
196.Polaraminoacidsareallexcept? a)Glutamicacid b)Histidine c)Glutamine d)Methionine CorrectAnswer-DAns.is'd'i.e.,Methionine
197.Majorformoffolicacidtotransferone carbonis? a)MethyleneTHF b)FormylTHF c)MethylTHF d)All CorrectAnswer-AAns.is'a'i.e.,MethyleneTHFFolicacidTheactiveformoffolicacid(pteroylglutamate)istetrahydrofolate(THF).THFservesasacarrierofone-carbon(C1)unit0duringseveralbiosyntheticreactionslikenucleicacidQandaminoacidmetabolism.Twoothercofactorsarealsoknowntobeinvolvedintheadditionofonecarbon(C1)unittoametabolicprecursor,biotinincarboxylationreactionandS-adenosylmethionine(SAM)asmethylatingagent.However,folicacidismoreversatilethaneitherofthesetwobecauseitcantransfertheC,unitsinseveraloxidationstates.THFactsasacarrierofonecarbonunit0.Theonecarbonunitscanbe:Methyl(C.113),methylene(CH2),methenyl(CH),formyl(CHO),orformimino(CH=NH).OnecarbonunitbindstoTHFthroughN5orN1?orbothN5,N'?position.Forexample,ifformylunitisattachedtoN-5,itiscalledN5-formylTHF;ifmethyleneunitisattachedtobothN5and1\l'?,itiscalledN5,N'?methyleneTHF.CarbonunitsattachedtoN5areformyl,formimino,ormethyl;
attachedtoN'?isformyl;andattachedtobothN5-N10aremethyleneormethenyl.So,variouspossibleTHFare:-N5-FormylTHF,N5-formiminoTHF,N5-methylTHF,N1?-formylTHF,N5-N10methyleneTHFandN5-N'?-methenylTHF.THFreceivestheC,unitsfromvariousdonormoleculesduringcatabolicreactionsandcantransfersthemtospecificacceptorsforthesynthesisofvariouscompounds.Themajorpointofentryforone-carbonunitintosubstitutedfolatesismethyleneTHF,whichisformedbythereactionofglycine,serineandcholine.Serineisthemostimportantsourceofsubstitutedfolatesforbiosyntheticreactions,andactivityofserinehydroxymethyltransferaseisregulatedbythestateoffolatesubstitutionandavailabilityoffolate.
198.Duringstarvation,muscleuses? a)Fattyacids b)Ketonebodies c)Glucose d)Proteins CorrectAnswer-AAns.is'a'i.e.,Fattyacids
199.Serotoninisderivedfrom- a)Tyrosine b)Tryptophan c)Phenylalanine d)Methionine CorrectAnswer-BAns.is'b'i.e.,Tryptophan[RefHarper29'/ep.300]Tryptophanisaprecursorforsynthesisofniacin(nicotinicacid),serotoninandmelatonin.
200.Majorapolipoproteinofchylomicrons? a)B-100 b)D c)B-48 d)None CorrectAnswer-CAns.is'c'i.e.,B-48
201.TrueaboutGlutathioneexcept? a)Tripeptide b)Formedfromglutamicacid,glycine,cysteine c)Actasantioxidantinreducedstate d)Alloftheabove CorrectAnswer-DAns.is`d'i.e.,AlloftheaboveGlutathioneGlutathioneisatripeptideofglutamieacid,cysteine,andglycine.Themoleculehasasulfhydryl(-SH)orthiolgrouponthecysteine,whichaccountsforitsstrongelectron-donatingcharacter.Itexistsintwoforms:reducedglutathioneorGSH.Inthereducedstate,thethiolgroupofcysteineisabletodonateareducingequivalent(H+e-)tootherunstablemolecules,suchasreactiveoxygenspecies.Indonatinganelectron,glutathioneitselfbecomesreactive,butreadilyreactswithanotherreactiveglutathionetoformglutathionedisulfide(GSSG)oroxidizedglutathione.GSHcanberegeneratedfromGSSGbytheenzymeglutathionereductase.Whileallcellsinthehumanbodyarecapableofsynthesizingglutathione,liverglutathionesynthesishasbeenshowntobeessential.TheliveristhelargestGSHreservoir.Becauseofitsreducingproperty,reducedglutathionehaspotentantioxidantaction.Functions:GSHisanextremelyimportantcellprotectant.Itdirectlyreducesreactivehydroxylfreeradicals,otheroxygencenteredfreeradicals,andradicalcentersonDNAandotherbiomolecules.GSHistheessentialcofactorformanyenzymeswhichrequirethiol-
reducingequivalents,andhelpskeepredox-sensitiveactivesitesonenzymesinthenecessaryreducedstate.GSHisusedasacofactorby?Multipleperoxidaseenzymes,todetoxifyperoxidesgeneratedfromoxygenradicalattackonbiologicalmolecules;Transhydrogenases,toreduceoxidizedcentersonDNA,proteins,andotherbiomolecules;andGlutathioneS-transferases(GST)toconjugateGSHwithendogenoussubstances(e.g.,estrogens)andtoexogenouselectrophiles(e.g.,areneoxides,unsaturatedcarbonyls,organichalides),anddiversexenobiotics.GSHisaprimaryprotectantofskin,lens,cornea,andretinaagainstradiationdamage,andthebiochemicalfoundationofP450detoxicationintheliver,kidneys,lungs,intestinalepithelia,andotherorgans.GSHactsasacarrierintransportofcertainaminoacidsacrossmembranesinthekidney.Glutathione(GSH)participatesinleukotrienesynthesis.
202.Concentrationofwhichisinversely relatedtotheriskofcoronaryheartdisease? a)VLDL b)LDL c)HDL d)None CorrectAnswer-CAns.is'c'i.e.,HDLThelevelofHDLinserumisinverselyrelatedtotheincidenceofMI.Asitis"antiatherogenic"or"protective"innature,HDLisknownas"goodcholesterol".HDLhasitsbeneficialeffectbyreversecholesteroltransport.
203.Maximumcholesterolisseenin? a)VLDL b)LDL c)HDL d)Chylomicrons CorrectAnswer-BAns.is'b'i.e.,LDLMaximumtriglyceridecontentChylomicronsMaximumexogenoustriglycerideChylomicronsMaximumendogenoustriglycerideVLDLMaximumcholesterolcontentLDL
204.Inhumans,endproductofpurine metabolism a)Allantoin b)Uricacid c)CO2 d)None CorrectAnswer-BAns.is'b'i.e.,Uricacid
205.Allaretrueaboutchaperonesexcept? a)Causefoldingofproteins b)Arelipidinnature c)MayhaveATPaseactivity d)Includeheatshockproteins CorrectAnswer-BAns.is'b'i.e.,ArelipidinnatureChaperonesareproteins(notlipid).ChaperonesCertainproteinsplayaroleintheassemblyorproperfoldingofotherproteinswithoutthemselvesbeingcomponentsofthelatter.Suchproteinsarecalledmolecularchaperones.MostchaperonesexhibitATPaseactivityandbindADPandATP.Thisactivityisimportantfortheireffectonfolding.SomePropertiesofChaperoneProteinsPresentinawiderangeofspeciesfrombacteriatohumansManyareso-calledheatshockproteins(Hsp)Someareinduciblebyconditionsthatcauseunfoldingofnewlysynthesizedproteins(eg,elevatedtemperatureandvariouschemicals)TheyblindtopredominantlyhydrophobicregionsofinfoldedproteinsandpreventtheiraggregationTheyactinpartasaqualitycontroloreditingmechanismfordetectingmisfoldedorotherwisedefectiveproteinsMostchapersonesshowassociatedATPaseactivity,withATPorADPbeinginvolvedintheprotein-chaperoneinteractionFoundinvariouscellularcompartmentssuchascytosol,mitochondria,andthelumenoftheendoplasmicreticulum
206.WhichVitaminisinvolvedinRedox reactions a)Pyridoxin b)Biotin c)Folicacid d)Riboflavin CorrectAnswer-DAns.is'd'i.e.,RiboflavinRiboflavinandniacinareinvolvedinredox(reductionandoxidation)reactions.
207.Ninhydrintestisusedfor? a)Bilesalts b)Aminoacids c)Nucleicacid d)Lipids CorrectAnswer-BAns.is'b'i.e.,AminoacidsImportantchemicalreactionsofaminoacidsFollowingaresomeimportantchemicalreactions.A.Reactionusedtodetermineaminoacidsequenceinpolypeptidechain:-Generally,aminoterminal(N-terminal)ofaminoacidistaggedwithsomereagent.Itissplitoffbyhydrolysisandtaggedaminoacidisidentified.Thereactionis,then,repeatedwithnewN-terminalofsubsequentaminoacidandsoon.Thetworeactionsareusedforidentificationofaminoacidsequence:?Sanger'sreaction:-UsesSanger'sreagent(1-fluoro-2,4-dinitrobenzene)totagaminoterminal.Edman'sreaction:-UsesEdman'sreagent(phenylisothiocyanate)totagaminoterminal.B.Reactionusedtoidentificationofindividualorgroupofaminoacids:-Thesereactionsarefrequentlyusedforqualitativedetectionandquantitativemeasurementofvariousaminoacids.Ninhydrintese:-Alla-aminoacids.Xanthophoreticreaction:-Aromaticaminoacidse(Tyrosine,tryptophan,phenylalanine).Millan'steste(Millon-Nassereaction):-Tyrosine?(phenolgroupoftyrosine).Thereforemillon'stestispositiveintyrosinosis?.Aldehydetest:-Tryptophan(indolering)
Hopkins-tolereaction:-Tryptophan(indolering)Sakaguch'sreaction:-Arginine(guanidiniumgroupofarginine).Sulphurtest:-Cysteine(sulphydrylgroup)Nitroprussidetest:-Cysteine(sulphydrylgroup)Pauly'stest:-Histidine(imidazolegroup)Biuretreaction:-PeptidebondDiazoreactionQ(Pauli's):-Histidineortyrosine.
208.Whichisnotadietaryfiber? a)Lignin b)Lactulose c)Pectin d)Cellulose CorrectAnswer-BAns.is'b'i.e.,LactuloseDietaryfibres(Review)DietaryfibreconsistsofunabsorbablecellwallandotherconsititutentsofvegetablefoodlikecelluloseQ,lignin,hemicellulosee,gums,pectins?,aliginatesandotherpolysaccharides.Inherbivorousanimals,intestinalmicrooganismbreakdownthesepolysaccharidesintoacetate,propionateandbutyrate.Thesepolysaccharidescontain13-glycosidiclinkages.Therefore,theycannotbedigestedbya-amylasepresentinhumansalivaandpancreaticjuicebecausea-amylasebreaksa-glycosidicbond(especially1-4alinkage).So,dietaryfibersarenotdigestedorhydrolyzedbutarefermentedbycolonicbacteriaexceptforlignin,whichisneitherdigestednorfermentedbyintestinalmicroorganisms?.Dietaryfibreabsorbeswaterintheintestine,swells,increasebulkofstoolbyincreasingwatercontentoffaecesandsoftenit,decreasestransittimebyfacilitatingcolonictansit."Thepresenceoffibreshortensthetransittimeseandincreasesthestoolbulk".Dietaryfibreisoftwotypes:- 1. Solublefibree:-Thesearepectin,aliginates,andgums.These
absorbupto15timesitsweightinwaterasitmovesthroughGIT,producingsofterstools.Itsgoodsourcesareoat,flaxseeds,peas,beans,apple,citrusfruits,carrots,bareleyandpsyllium. 2. Insolublefibre?:-Thesearecellulose,hemicelluloseandlignin. Thesepromotemovementofmaterialthroughdigestivesystemandincreasesstoolbulk.Itsgoodsourcesarewheatflour,wheatbran,nutsandvegetables.
209.ATPisgeneratedinETCby? a)Na'ATPase b)Cl-ATPase c)FoF,ATPase d)ADPKinase CorrectAnswer-CAns.is`c'i.e.,FoFiATPase
210.Atractilosideactas? a)Uncoupler b)Inhibitorofoxidativephosphorylation c)InhibitorofcomplexIofETC d)InhibitorofcomplexIIIofETC CorrectAnswer-BAns.is'b'i.e.,InhibitorofoxidativephosphorylationInhibitorsofelectrontransportchain?Inhibitorsofrespiratorychainmaybedividedintothreegroups:?1.InhibitorsofelectrontransportchainproperTheseinhibitorsinhibittheflowofelectronsthroughtherespiratorychain.Thisoccursatfollowingsites.ComplexI(NADHtoCoQ)isinhibitedby:-Barbiturates(amobarbital),PiericidinA(anantibiotic),rotenone(aninsectiside),chlorpromazine(atranquilizer),andguanethidine(anntihypertensive).TheseinhibitorsblockthetransferofreducingequivalentsfromFeSproteintoCoQ.ComplexIIisinhibitedby:-CarboxinandTTFAinhibittransferofelectonfromFADH2toCoQ,whereasmalanatecompetitivelyinhibitfromsuccinatetocomplexII.ComplexIII(CytochromebtocytochromeCI)isinhibitedby:-Dimercaprol,antimycinA,BAL(Britishantilewisite),Naphthyloquinone.TheseinhibitorsblockthetransferofelectronsfromcytochromebtocytochromeComplexIV(cytochromeCoxidase)isinhibitedby:-Carbonmonoxide,CN-,H2Sandazide(N3-).Theseinhibitorsblockthetransferofelectronsfromcytochromeaa3tomolecularoxygenandthereforecantotallyarrestcellularrespiration.2.Inhibitorsofoxidativephosphorylation
ThesecompoundsdirectlyinhibitphosphorylationofADPtoATP.OligomycininhibitsFocomponentofF0F,ATPase.Atractilosideinhibitstranslocase,atransportproteinthattransportsADPintomitochondriaforphosphorylationintoATP.3.UncouplesAsthenamesuggests,thesecompondsblockthecoupelingofoxidationwithphosphorylation.ThesecompoundsallowthetransferofreducingequivalentsinrespiratorychainbutpreventthephosphorylationofADPtoATPbyuncouplingthelinkagebetweenETCandphosphorylation.Thustheenergyinsteadofbeingtrappedbyphosphorylationisdissipatedasheat.Uncouplersmaybe:- 1. Natural:-Thermogenin,thyroxine2. Synthetic:-2,4-dinitrophenol(2,4-DNP),2,4-dinitrocresol(2,4- DNC),andCCCP(chlorocarbonylcyanidephenylhydrazone).
211.Riboflavinisaconstituentof? a)FMN b)NAD c)PLP d)THF CorrectAnswer-AAns.is'a'i.e.,FMNRiboflavinisalsocalledWarburgyellowenzyme.Riboflavinprovidesthereactivemoietiesofthecoenzymesflavinmononucleotide(FMN)andflavinadeninedinucleotide(FAD).Flavincoenzymesareinvolvedinoxidoreductionreactionsaselectroncarriers.Thesereactionsincludethemitochondrialrespiratorychain,keyenzymesinfattyacidandaminoacidoxidationandthecitricacidcycle.
212.Ratelimitingstepinpyrimidine synthesis? a)Dihydro-orotase b)Ornithinetranscarbomoylase c)Aspartatetranscarbomoylase d)Carbamoylphosphatesynthase-I CorrectAnswer-CAns.is'c'i.e.,Aspartatetranscarbomoylase
213.Allarecharacteristicsofgeneticcode? a)Overlapping b)Nonambiguous c)Universal d)Degeneracy CorrectAnswer-AAns.is'a'i.e.,OverlappingCharacteristicofgeneticcodesGeneticcodeshavefollowingcharacteristics?1.Universal:-Eachcodonspecificallycodesforsameaminoacidinallspecies,e.g.UCAcodesforserineandCCAcodesforprolineinallorganisms.Thatmeansspecificityofcodonhasbeenconservedfromveryearlystagesofevolution.Exceptiontotheuniversalityofgeneticcoderarefoundinhumanmitochondria,wherethecode:-UGAcodesfortryptophaninsteadofservingasastopcodon.AUAcodesformethionineinsteadofisoleucine?CUAcodesforthreonineinsteadofleucine.AGAandAGGserveasstopcodoninsteadofcodingforarginine.2.Unambiguous/Specific:-Aparticularcodonalwayscodesforthesameaminoacid.ForexampleCCUalwayscodesforprolineandUGGalwayscodesfortryptophan.3.Degeneracy/Redundancy:-Agivenaminoacidmayhavemorethanonecodon.Forexample,CCU,CCC,CCAandCCGallfourcodonscodeforproline.Therefore,thereare61codonsfor20aminoacids.4.Stoporterminationornonsensecodons:-Threeofthe64possiblenucleotidetripletsUAA(amber),UAG(Ochre)andUGA(opal)donotcodeforanyaminoacid.Theyarecallednonsense
codonsthatnormallysignalterminationofpolypeptidechains.Thus,thoughthereare64possibletripletcodons,only61codesfor20aminoacids(asremainingthreearenon-sensecodons).5.Nonoverlappingandnonpuntate(Commaless):-Duringtranslation,thecodeisreadsequentially,withoutspacerbases,fromafixedstartingpoint,asacontinuoussequenceofbases,taken3atatime,e.g.AUGCUAGACUUUisreadasAUG/CUA/GAC/UUUwithout"ponctation"(coma)betweencodons.
214.Whichofthefollowingisanexampleof Trinucleotiderepeatmutation? a)Huntington'schorea b)Fragile-X-syndrome c)Friedreichataxia d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,AlloftheaboveTrinucleotiderepeatmutationInthistypeofmutationacodon(i.e.trinucleotidesequence)undergoesamplificationandthesamecodonisrepeatedcontinuouslysomanytimesinthechain.DiseasesassociatedwithtrinucleotiderepeatmutationareHuntington'sdisease(CAGrepeat),Spinocerebellarataxia(CAGrepeat),friedreichataxia(GAArepeat),fragile-X-syndrome(GGGorGCCrepeat),dystrophiamyotonica(CTG/CUGrepeat),X-linkedspinobulbarmuscularatrophy(CAGrepeat)anddentorubralpallidolusianatrophy(CAGrepeat).
215.Whichofthefollowingisthemajor proteoglycanofsynovialfluid? a)Chondroitinsulfate b)Dermatansulfate c)Heparansulfate d)Hyaluronicacid CorrectAnswer-DAns.is'd'i.e.,Hyaluronicacid Distribution Hyaluronic Synovialfluid(providesviscosity),vitreoushumor, acid looseconnectivetissue) Chondroitin Cartilage,bone,tendon,ligament,cornea sulfateDermatan Pliabilityofskin,andheartvalves,widedistribution sulfateKeratan Hornystructureslikehair,nails,claws,horn,hoofs sulfate Alsopresentincornea Heparin Mastcells Heparansulfate Skinfibroblast,aorticwall
216.ThemainfunctionofVitaminCinthe bodyis a)Coenzymeforenergymetabolism b)Regulationoflipidsynthesis c)Involvementasantioxidant d)Inhibitionofcellgrowth CorrectAnswer-CAns.is'c'i.e.,InvolvementasantioxidantVitaminC(Ascorbicacid)Ascorbicacid(VitaminC)isalsocalledantiscorbuticfactor.Itisveryheatlabile,especiallyinbasicmedium.Ascorbicaciditselfisanactiveform.MaximumamountofvitaminCisfoundinadrenalcortex.Ascorbicacidfunctionsasareducingagentandscavangeroffreeradicals(antioxidant).Itsmajorfunctionsare:-Incollagensynthesis:-VitaminCisrequiredforpost-translationalmodificationbyhydroxylationofprolineandlysineresiduesconvertingthemintohydroxyprolineandhydroxylysine.ThusvitaminCisessentialfortheconversionofprocollagentocollagen,whichisrichinhydroxyprolineandhydroxylysine.Throughcollagensynthesis,itplaysaroleinformationofmatrixofbone,cartilage,dentineandconnectivetissue. 1. Synthesisofnorepinephrinefromdopaminebydopamine-(3- monoxygenase(dopamine-f3-hydroxylase)requiresVitaminC. 2. Carnitinesynthesis3. Bileacidsynthesis:-7-ct-hydroxylaserequiresvitaminC.4. Absorptionofironisstimulatedbyascorbicacidbyconversionof ferrictoferrousions.
5. Duringadrenalsteroidsynthesis,ascorbicacidisrequiredduring hydroxylationreactions. 6. Tyrosinemetabolism:-OxidationofP-hydroxy-phenylpyruvateto homogentisate. 7. Folatemetabolism:-Folicacidisconvertedtoitsactiveform tetrahydrofolatebyhelpofVitaminC.
217.Enzymespecificityisgivenby? a)Km b)Vrm,, c)Both d)None CorrectAnswer-AAns.is'a'i.e.,Km.TheKmofanenzymeistheconcentrationofthesubstratethatenablestheenzymetofunctionathalfmaximumactivityandisthereforeameasureofthespecificityofasubstrate.fortheenzyme"ClinicalbiochemistryActuallyenzymespecificityisnotmeasuredbyKmalone.ItismeasuredbytheratioKcat/Kmwhichisasecondorderrateconstantforthereactionbetweensubstrateandfreeenzyme.Thisratioisimportant,foritprovidesadirectmeasureofenzymeefficiencyandspecificity.Note:Kcatisturnovernumberandmeasurestherateofthecatalyticprocess.
218.Naturaluncoupleris? a)Thermogonin b)2,4nitrophenol c)2,4Dinitrophenol d)Oligomycin CorrectAnswer-AAns.is'a'i.e.,ThermogeninAmongstthegivenoptions,a,bandcareuncouplers.However,onlythermogenin,amongthesethreeisanatural(physiological)uncoupler.UncouplesAsthenamesuggests,thesecompondsblockthecoupelingofoxidationwithphosphorylation.ThesecompoundsallowthetransferofreducingequivalentsinrespiratorychainbutpreventthephosphorylationofADPtoATP?byuncouplingthelinkagebetweenETCandphosphorylation.Thustheenergyinsteadofbeingtrappedbyphosphorylationisdissipatedasheat.Uncouplersmaybe:-Natural:-Thermogenin,thyroxineSynthetic:-2,4-dinitrophenol(2,4-DNP),2,4-dinitrocresol(2,4-DNC),andCCCP(chlorocarbonylcyanidephenylhydrazone).
219.Lipidwithhighestmobilityis? a)HDL b)LDL c)VLDL d)Chylomicrons CorrectAnswer-AAns.is`a'i.e.,HDLHDL:-Hasmaximumelectrophoreticmobility,hasmaximumdensity,hasminimumlipidcontent,hasmaximumprotein(apoprotein)content,aresmallestinsize,hasmaximumphospholipid,hasminimumtriglycerides.Chylomicrons:-Havenoelectrophoreticmobility,haveminimumdensity,havemaximumlipidcontent,haveminimumproteincontent,arelargestinsize,haveminimumphospholipids,havemaximumtriglycerides.
220.ApolipoproteinEisrichin? a)Lysine b)Arginine c)Histidine d)Methionine CorrectAnswer-BAns.is'b'i.e.,ArginineArgininerichapo-EisisolatedfromVLDL.Itcontainsargininetotheextentof10percentofthetotalaminoacidsandaccountsfor5to10percentoftotalVLDLapoproteinsinnormalsubjects.
221.Whichenergymoleculegives10.5kcal/ molecule? a)ATP b)GTP c)Creatinephosphate d)Glucose-6-phosphate CorrectAnswer-CAns.is'c'i.e.,CreatinephosphateAcompoundthatliberates7Kcal/molormoreonhydrolysisiscalledhighenergycompound,oracompoundthatonhydrolysisundergoesalarge(7kcal/mol)decreaseinfreeenergy(AG)understandardconditioniscalledhighenergycompound,i.e.,AG7Kcal/mol.Forexample,ATPliberates7.3Kcal/molonhydrolysis Metabolite AG LiberatedenergyinKcallmole Phosphoenolpyruvate -14.8 14.8 Carbamoylphosphate -12.3 12.3 1,3-Bisphosphoglycerate -11-8 11.8Acidphosphate -112 112 Creatinephosphate -10.3 10.3 Argininephosphate -7.6 7.6 ATPtoADP+Pi -7.3 7.3 ATPtoAMP+PPi -7-7 7.7 Glucose-1-phosphate -5.0 5.0 Glucose-6-phosphate -3.3 3.3 Glycerol-l-phosphate -2.2 2.2
222.Branchingenzymeisfoundin? a)Glycogenesis b)Glucogenesis c)Glycogenolysis d)Glycolysis CorrectAnswer-AAns.is'a'i.e.,Glycogenesis
223.Whichofthefollowingisnota phospholipid? a)Lecithine b)Plasmalogen c)Cardiolipin d)Ganglioside CorrectAnswer-DAns.is'd'i.e.,GangliosidePhospholipidsare: 1. Glycerophospholipids(glycerolcontaining):-Phosphatidylcholine (lecithin),phosphatidylethanolamine(cephaline),phosphatidylserine,phosphatidylinositol,plasmalogens,lysophospholipids,cardiolipin. 2. Sphingophospholipids(sphingosinecontaining):-Sphingomyeline
224.Themechanismbywhichmercury causesdamage? a)Bindsto-SHgroupofenzyme b)Directlytoxic c)InhibitsETC d)Inhibitsproteinsynthesis CorrectAnswer-AAns.is'a'i.e.,Bindsto-SHgroupofenzymeHeavymetaltoxicityiscausedbytightbindingofametalsuchasmercury(Hg),lead(Pb),aluminium(Al),oriron(Fe)toafunctionalgroupofenzyme.Mercury,forexample,bindstoreactivesulfhydrylgroups(-SH)intheactivesiteofsomanyenzymes,thatithasbeendifficulttodeterminewhichoftheinhibitedenzymeisresponsibleformercurytoxicity.Leadalsohashighaffinityforsulfhydrylgroup.
225.Q10inenzymematcheswith? a)2 b)4 c)8 d)10 CorrectAnswer-AAns.is'a'i.e.,2Mostenzymeshowa50-300%(average200%)increaseinreactionratewhenthetemperatureisincreasedby10?,andtheratioofrateconstantattwotemperatures10?apartisusuallybetween1.5to4(average2)formostenzymes.ThisvalueistermedasQ10."Therateofenzymaticreactiondoubleswithevery10?riseintemperature."
226.Creatineismadeupofall,except? a)Glycine b)Alanine c)Methionine d)Arginine CorrectAnswer-BAns.is'b'i.e.,Alanine
227.InureacyclewhichdefectisanX linkeddisease? a)Ornithinetranscarbamylase b)Aspartatetranscarbamylase c)Arginase d)Argininosuccinatesynthase CorrectAnswer-AAns.is'a'i.e.,Ornithinetranscarbamylase
228.Trueregardingcollagensynthesisisall except? a)Synthesizedinribosomesaspreprocollagen b)HydroxylationofprolineoccursinGolgiapparatus c)HydroxylationoflysineoccursinER d)TriplehelixassemblyoccursinER CorrectAnswer-BAns.is'b'i.e.,HydroxylationofprolineoccursinGolgiapparatus
229.TypeofcollagenfoundinspaceofDisse inliveris- a)CollagenI&II b)CollagenIII&IV c)CollagenII& d)CollagenII&V CorrectAnswer-BAns.is'b'i.e.,CollagenIII&IV
230.Whichispredominantinnormal healthyhuman? a)LDH1 b)LDH2 c)LDH3 d)LDH4 CorrectAnswer-BAns.is'b'i.e.,LDH2 Submit Percentagein Isoenzyme Issue composition serrum LDHI HHHH Myocardium,RBC 30 LDH2 HHHM Myocardium,RBC 35 LDH3 HHMM Brain,Kidney 20 Skeletalmuscle, LDH4 HMMM 10 LiverSkeletalmuscle, LDH5 MMMM 5 Liver
231.Physiologicaluncoupleris? a)Thyroxine b)Freefattyacids c)Thermogenin d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,Alloftheabove
232.WhichofthefollowingisAldosugar? a)Fructose b)Erythrulose c)Glucose d)None CorrectAnswer-CAns.is`c'i.e.,Glucose Numberof Aldoses Sugar Ketoses(ketosugars) carbonatoms (Aldosugars) Trioses 2 Glyceraldehyde Dihydroxyacetone Tetroses 4 Erythrose Erythrulose Pentoses 5 Ribose,Xylose Ribulose,xylulose Glucose, Hexoses 6 galactase, Fructose mannose Heptoses 7 Glucoheptose Sedoheptulose
233.Keyenzymeofgluconeogenesisareall except? a)Pyruvatecarboxylase b)PEPcarboxykinase c)Pyruvatekinase d)Glucose-6-phosphatase CorrectAnswer-CAns.is'c'i.e.,PyruvatekinaseMitochondrialpyruvatecarboxylasecatalyzesthecarboxylationofPyruvatetoOxaloacetate,ItisanATP-requiringreaction,Biotinisthecoenzyme.PhosphoenolpyruvateCarboxykinase:Catalyzesthedecarboxylationandphosphorylationofoxaloacetatetophosphoenolpyruvate(PEPCK)(Cytosol)usingGTPasthephosphatedonor.Theconversionofglucose-6-phosphatetoglucoseiscatalyzedbyglucose6-phosphatase
234.Fructoseintoleranceisduetodeficiency of? a)AldolaseB b)Fructokinas c)Triokinas d)AldolaseA CorrectAnswer-AAns.is'a'i.e.,AldolaseBDiseaseDificientenzymesEssentialfructosuriaFructokinaseHereditaryfructoseintoleranceAldolase-BGalactosemiaGalactose-l-phosphateuridyltransferase(mostcommon),GalactokinaseUDP-galactose-4-epimeraseLactoseintoleranceLactase((3-galactosidase)EssentialpentosuriaL-xylulosedehydrogenase(xylulosereductase)
235.Whatisessentialfortransferoffattyacid acrossmitochondrialmembrane- a)Creatine b)Creatinine c)Carnitine d)None CorrectAnswer-CAns.is'c'i.e.,Carnitine
236.Hexokinaseis? a)Ligase b)Transferase c)Oxidoreductase d)Reductase CorrectAnswer-BAns.is`b'i.e.,Transferase
237.Ketonebodyformationwithout glycosuriaisseenin? a)Diabetesmellitus b)Diabetesinsipidus c)Starvation d)Obesity CorrectAnswer-CAns.is'c'i.e.,StarvationAmongstthegivenoptions,DMandstarvationarethecausesofketosis 1. Diabetes:-Ketosiswithhyperglycemiaandglycosuria2. Prolongedstarvation:-Ketosiswithlowornormalglucoseand withoutglycosuria.IndiabeticKetoacidosis:-(i)PositiveRothera'stest(duetoketonebodies)(ii)PositiveBenedict'stest(duetopresenceofreducingsugarinurine)InStarvationketosis:-(i)PostiveRothera'stest(duetoketonebodies),(ii)NegativeBenedict'stest(nosugarinurine)
238.Aminoacidwithdoublechiralis? a)Phenyalanine b)Threonine c)Tryptophane d)Tyrosine CorrectAnswer-BAns.is'b'i.e.,Threonine
239.AtphysiologicalpHDNAis? a)Acidic b)Negativelycharged c)Amphipathic d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,AlloftheaboveDNAisamphipathicAmphipathicmoleculeisonewhichcontainsbothpolar(hydrophilic)andnonpolar(hydrophobic)regionsinitsstructure,i.e.thepartofmoleculeiswatersolubleandpartiswaterinsoluble.InDNAhelixHydrophilic(polar)deoxyribose-phosphateofeachchainisonoutsideofmolecule.Hydrophobic(nonpolar)basesarestackedin.ThusDNAisregardedasamphipathicinnature.DNAisnegativelychargedandacidicPhosphategroupliesonoutsideofmoleculeofDNA.EachphosphategrouphasanegativechargeatphysiologicalpH,makingDNAanegativelycharge(anion)atphysilogicalpH."Histonesarestronglycationicandcanbindnon-specificallytostronglyaniomicDNA"Harper"AtphysiologicalpHDNAisnegativelycharged,andisassociatedwithpositivelycharged(basic)histones"RonaldHofmann.oAnionicmoleculesareacidicinnature.
240.Sourceofammoniainurine? a)Glutaminase b)Urease c)Glutamatedehydrogenase d)Arginase CorrectAnswer-AAns.is'a'i.e.,GlutaminaseInmanytissueslikeliver,kidneyandbrain,ammoniacombineswithglutamatetoyieldglutamine,bytheactionofglutaminesynthase.Thebrainisarichsourceofglutaminesynthaseanditpredominantlydetoxifiesammoniabythisroute.ATPADP+PiGlutamate+NH,4GlutamineGlutaminesynthetaseGlutamineisanontoxicmajortransportformofammonia.Theglutamineistransportedbybloodtoliverwheredeamination(removalofaminogroup)ofglutaminetakesplace.Glutaminasecleavesglutaminetoyieldglutamateandfreeammonia(ammoniumion).Theammoniaisconvertedbylivertourea.0H2Glutamine________________________Glutamate+NH,GlutaminaseFormationandsecretionammoniabyrenaltubularcellsmaintainacidbasebalance.Ammoniaisformedfromglutaminebyglutaminase.Excretionofammoniaincreasesinmetabolicacidosisanddecreasesinmetabolicalkalosis.
241.Albuminbindswithallexcept? a)Steroid b)Calcium c)FFA d)Thyroxine CorrectAnswer-DAns.is'd'i.e.,ThyroxineAlbuminisinvolvedintransportofseveralsubstancesbecauseofitspredominantlypolarnature.Nearly40%ofplasmacalciumisbound-upwithalbumin.OthersubstanceswhichareBound-upand/ortranportedbyalbuminare:? 1. Freefattyacids2. Bilirubin3. Steroids4. Manynonpolardrugs ComingbacktoquestionThyroxinealsobindstoalbumin,butitisnotthemajortransportproteinforthyroxin.Mostofthethyroxineistransportedbyglobulin.Thyroxinebindingplasmaproteinsare:- 1. ThyroxinebindingglobulinMajorthyroidhormonebindingprotein2. Thyroxinebindingalbumin3. Thyroxinebindingpre-albumin Thus,amongthegivenoptions,thyroxineisthebestanswer.
242.Chemicalprocessinvolvedinconversion ofprogesteronetoglucocorticoidsis a)Methylation b)Hydroxylation c)Carboxylation d)None CorrectAnswer-BAns.is`b'i.e.,Hydroxylation
243.Gluconeogenesisoccursinallexcept? a)Liver b)Kidney c)Gut d)Muscle CorrectAnswer-DAns.is'd'i.e.,MuscleGluconeogenesisoccursmainlyintheliverandtoalesserextentinrenalcortex.Somegluconeogenesiscanalsooccurinsmallintestine,butitisnotsignificant.Someofthereactionsofgluconeogenesisoccursinthemitochondriabutmostoccurincytosol.Gluconeogenesiscannotoccurinmuscles.Glucose-6-phosphataseisabsentinmusclestherefore,glucose-6-phosphatecannotbedegradedtofreeglucoseinmuscles.Moreover,glucose-6-phosphatecannotdiffuseoutofthemuscles.Therefore,musclecannotprovideglucosetomaintainbloodglucoselevel.Rather,muscleglycogenactsasasourceofenergy;theglucose-6phosphateenterstheglycolysistoproduceenergy.
244.GLUT2receptors? a)Insulindependent b)Insulinindependent c)Foundincardiacmuscle d)Foundinbrain CorrectAnswer-BAns.is'b'i.e.,InsulinindependentGLUT-2isinsulinindependent(insulindependentGLUTisGLUT-4).ItisfoundinB-cellsofisletsofpancreas,liver,epithelialcellsofsmallintestineandkidney.Alsoseeexplanation-4ofsession-2.
245.Whichofthefollowinghasantioxidant property? a)Selenium b)Copper c)Zinc d)All CorrectAnswer-DAns.is'd'i.e.,AllTheactivityoftheantioxidantenzymesdependsonsupplyofminerals:? 1. Manganese2. Copper3. Zinc4. Selenium Manganese,copperandzincarerequiredfortheactivityofsuperoxidedismutase.Seleniumisrequiredfortheactivityofglutathioneperoxidase.
246.ThenumberofATPsgeneratedinkrebs cycleare? a)12 b)24 c)15 d)30 CorrectAnswer-BAns.is'b'>b'i.e.,24OneturnoftheTCAcycle,startingwithacetylCoAproduces10ATPs.Whenthestartingmoleculeispyruvate,theoxidativedecarboxylationofpyruvate,theoxidativedecarboxylationofpyruvateyields2.5ATPsandtherefore,12.5ATPsareproducedwhenstartingcompoundispyruvate.Since,twomoleculesofpyruvateentertheTCAcyclewhenglucoseismetabolized(glycolysisproduces2moleculesofpyruvate),thenumberofATPsisdoubled.Therefore,25ATPmolecules,perglucosemolecule,areproducedwhenpyruvateenterstheTCAcycle.Note:PreviouslycalculationsweremadeassumingthatNADHproduces3ATPsandFADHgenerates2ATPs.Thiswillamountanetgenerationof30ATPmoleculesinTCApermoleculeglucoseandtotal38moleculesfromstarting.RecentexperimentsshowthatthesevaluesareoverestimatesandNADHproduces2.5ATPsandFADHproduces1.5ATPs.Therefore,netgenerationduringTCAis25ATPsandcompleteoxidationofglucosethroughglycolysispluscitricacidcycleyieldanet32ATPs.Energyyield(numberofATPgenerated)permoleculeofglucosewhenitiscompletelyoxidizedthroughglycolysispluscitricacidcycle,underaerobicconditions,isasfollows:-
Noof Methodof NoofATPs ATPs Pathway Step Enzyme Source gainedATP perglucose Asperold formation (new calculation calculation) Glycolysis 1 Hexokinase Minus Minus1 Do 3 Phosphofructokinase Minus Minus1 NADH Glyceraldehyde-3-p 2.5x2= Do 5 Respiratory 3x2=6 DH 5 chainSubstrate 1x2-- Do 6 1,3-BPGkinaseATP 1x2=2 level 2 ATP 1x2 Do 9 Pyruvatekinase Substrate 1x2=2 =2 levelNADH Pyruvate 2.5x2= Pyruvate Respiratory 3x2=6 to 5 ? chain Acetyl Dehydrogenase CoA NADH 2.5x2= TCA IsocitrateDH Respiratory 3x2=6 5 cycle 3 chainNADH Alphaketoglutarate 2.5x2= Do 4 Respiratory 3x2=6 DH 5 chainGTP 1x2= Do 5 Succinatethiokinase Substrate 1x2=2 2 level Succicinate Respiratory 1.5x2= Do 6 2x2=4 DHFADH2 chain 3 Do 8 MalateDH NADH 2.5x2= 3x2=6Respiratory 5chain Netgenerationinglycolyticpathway9minus2=710
minus2=8Generationinpyruvatedehydrogenasereaction5?6Generationincitricacidcycle20?24NetgenerationofATPfromoneglucosemole32?38
247.OneKrebscyclegenerateshowmany ATP? a)6 b)12 c)24 d)36 CorrectAnswer-BAns.is'b'i.e.,12Thisquestionisslightlydifferentfrompreviousone.HeretheexaminerisaskingaboutthegeneraionofATPsperTCAcycle.InasingleTCAcycle10moleculesofATPareproduced(12moleculesaccordingtooldercalculations).
248.Glutathionerequireswhichvitamintoact asantioxidant? a)VitaminE b)Niacin c)VitaminC d)VitaminA CorrectAnswer-BAns.is'b'i.e.,Niacin
249.Metabolicchangeseeninstarvationare allexcept? a)Increasedgluconeogenesis b)Increasedglycolysis c)Ketogenesis d)Protiendegradation CorrectAnswer-BAns.is'b'i.e.,Increasedglycolysis
250.Catecholaminesaresynthesizedfrom? a)Tryptophan b)Tyrosine c)Methionine d)Histidine CorrectAnswer-BAns.is'b'i.e.,TyrosineCatecholamines(epinephrine,norepinephrineanddopamine)aresynthesizedfromtyrosin.Hasbeenexplainedinpreviousseesions.
251.
Whichoftheenzymeofglycolysisisapartofgluconeogenesis? a)Pyruvatekinase b)PFK c)Hexokinase d)Phosphoglyceratekinase CorrectAnswer-DAns.is'd'i.e.,PhosphoglyceratekinaseSevenofthereactionsofglycolysisarereversibleandareusedinthesynthesisofglucosebygluconeogenesis.Thus,sevenenzymesarecommontobothglycolysisandgluconeogenesis:(i)Phosphohexoseisomerase;(ii)Aldolase;(iii)Phosphotrioseisomerase,(iv)Glyceraldehyde3-phosphatedehydrogenase;(v)Phosphoglyceratekinase;(vi)Phosphoglyceratemutase;(vii)Enolase.Threereactionsofglycolysisareirreversiblewhicharecircumventedingluconeogenesisbyfourreactions.So,enzymesatthesestepsaredifferentinglycolysisandgluconeogenesis.ReactionsEnzymeinglycolysisEnzymeingluconeogenesisGlucose?Glucose-6-PHexokinase/glucokinaseGlucose-6-phosphataseFructose-6-P?Fructose-I,6-BPPhosphofructokinaseFructose-1-6-bisphosphatasePhosphoenolpyruvate?PyruvatePyruvatekinasePyruvatecarboxylasePEPcarboxykinase
252.Molecularinteraction,foundinthe structureofDNA- a)Hydrogenbond b)Glycosidicbond c)Covalentinteractions d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,Alloftheabove
253.Pyridoxineisusedintreatmentof? a)Galactosemia b)Phenylketonuria c)Propionicacidemia d)Homocystinuria CorrectAnswer-DAns.is'd'i.e.,Homocystinuria InbornerrorofmetabolismandTreatment Alkaptonuria VitaminC,Folicacid Homocystinuria Pyridoxine+FolicacidAlkalizationofurine+d-Penicillamine, Cystinuria Captopril Hartnupdisease Nicotinamide Multiplecarboxylase Biotin eficiencyMethylmalonicacademia VitaminB12Hyperoxaluria Pyridoxine Tyrosinemia NTBC,LiverTransplantation
254.Membraneproteinsaresynthesizedin? a)Freeribosome b)Boundribosome c)Nucleolus d)Mitochondria CorrectAnswer-BAns.is'b'i.e.,BoundribosomeRibosomesRibosomesaretheactualsitesofproteinsynthesisQ.TheribosomesaresmallgranulesofRNAs.RibosomesareusuallyoccurinclusterscalledpolyribosomesattachedtoonemRNAmolecule,anarrangementthatincreasestherateofpolypeptidesynthesis.Therearetwotypesofpolyribosomes:- 1. Free(cytosolic):-Presentfreeincytosol.2. Boundpolyribosome:-PresentonroughER. Bothtypescansynthesizeprotein:? ProteinssynthesizedbypolyribosomesCytosolic(free) Bound(roughER)Polyribosomes PolyribosomesCytosolicproteins,e.g., Synthesizeallmembraneproteins HemoglobinCytoskeletalproteins Mitochondria]membrane Mitochondrialproteins ERmembraneGolgiapparatusmembraneuPlasma Nuclearproteins membrane Peroxisomalprotein Secretoryproteins Lysosomalenzym
255.TransminationofAspartateforms? a)Pyruvate b)Acetly-CoA c)Oxaloacetate d)Alanine CorrectAnswer-CAns.is'c'i.e.,OxaloacetateTransaminationTransaminationinvolvesthereversibletransferofa-aminogroupofa-aminoacidtoana-ketoacid('toformanewaminoacidandanewketoacid.Theenzymecatalyzethereactioniscalledaminotransferase(transaminase).Mosttransaminasesusea-ketoglutarate(a-ketoacid)asacommonacceptorofa-aminogroupofa-aminoacids.Alltransaminasesrequirepyridoxalphosphate(VitaminB6)asacoenzymneQ.Someofthemostimportanttransaminasesare:-Alaninetransaminase(ALT)alsocalledglutamatepyruvatetransaminase(GPT):-Itcatalyzesthetransferofaminogroupofalaninetoa-ketoglutarateresultinginformationofpyruvateandL-glutamateQ.ALTL-AlanineQ+a-ketoglutarateQ_____PyruvateQ+L-glutamateQPLPAspartatetransaminase(AST)alsocalledglutamateoxaloacetatetransaminase(GOT):Itcatalyzesthetransferofaminogroupofaspartatetoa-ketoglutarateresultinginformationofoxaloacetateandL-glutamate.ASTL-Aspartate+a-ketoglutarateOxaloacetate+L-glutamatePLP
Mostaminoacidsundergotransaminationreactionexceptlysine,threonine,prolineandhydroxyproline.Alltheaminogroupsfromaminoacidsthatundergotransaminationarecollectedintoonecommonaminoacid,i.e.,glutamate.ThisisimportantbecauseL-glutamateistheonlyaminoacidthatundergoesoxidativedeaminationatanappreciablerateinmammaliantissue.Thus,formationofammoniafromaminoacidsoccursmainlyviathea-aminonitrogenofglutamate.Transaminationisnotrestrictedtoa-aminogroups.The6-aminogroupofornithine(butnottheE-aminogroupoflysine)undergoestransmination.
256.Interactioninvolvedinprimarystructure ofprotein? a)Hydrogenbond b)Disulfidebond c)Peptidebond d)Electrostaticbond CorrectAnswer-CAns.is`c'i.e.,Peptidebond
257.AllaretrueaboutvitaminEexcept? a)Actasantioxidant b)Preventlipidperoxidationofcellmembrane c)Watersolublevitamin d)Chemicallytocopheral CorrectAnswer-CAns.is'c'i.e.,WatersolublevitaminVitaminEisafatsolublevitamin(notwatersoluble).Allotheroptionsarecorrect.
258.Bloodformoffolicacidis- a)Folinicacid b)Pteroglutamate c)MethylTHE d)None CorrectAnswer-CAns.is'c'i.e.,MethylTHEFolicacidisabsorbedinthejejunum.Followingabsorption,folicacidistransportedinbloodbytwo(3-globulins.Themajorcirculatingformismethyltetrahydrofolateandthenormalconcentrationrangeis5-15ng/ml.Onceitarrivesintheliver,themethylderivatesaretakenupbyhepatocyteswherevariouscoenzymeareproduced.oFolicacidisnotstoredinthebody.RemembersMajorcirculatingformoffolicacid--0methylTHEMajorpointofenteryfor1carbontransferbysubstituedfolate-4methyleneTHE
259.Primaryhypercholesterolemiais? a)TypeI b)TypeHa c)TypeIIb d)TypeIII CorrectAnswer-BAns.is'b'i.e.,TypeHa
260.Salvagepurinesynthesisrefersto? a)Synthesisofpurinefromribose-5-phosphate b)Synthesisofpurinefrompyrimidine c)Synthesisofpurinenucleotidesfrompurinebases d)Noneoftheabove CorrectAnswer-CAns.is'c'i.e.,SynthesisofpurinenucleotidesfrompurinebasesTwoimportantpurinenucleotidesaresynthesized:(i)adenosinemonophosphate(AMP)and(ii)guanosinemonophosphate(GMP).ThenAMPandGMPareconvertedtootherpurinenucleotideslikeADP,ATP,GDP,GTPetc.Purinenucleotidescanbesynthesizedbytwopathways-(1)Denovosynthesisand(2)Salvagepathway.Denovopathway(Denovosynthesis)Indenovopathway,thepurinenucleotidesaresynthesizedfromamphibolicintermediates.Amphibolicintermediatesaretheintermediarymetabolitesofamphibolicpathways(eg.citricacidcycle)whichhavedualpurposes,ie.theyserveincatabolismaswellasinanabolism.Indenovosynthesis,purineringisformedfromvarietyofprecursorsisassembledonribose-5-phosphate.Precursorsfordenovosynthesisare? 1. GlycineprovidesCa,C5andN72. AspartateprovidesN,3. GlutamineprovidesN3andN94. TetrahydrofolatederivativesfurnishC2andC85. CarbondioxideprovidesCo SalvagepathwayofpurinenucleotidesynthesisFreepurinebases(adenine,guanineandhypoxanthine)andpurine
nucleosidesareformedincellsduringthemetabolicdegradationofnucleicacidsandnucleotides.Thesefreepurinebasesandpurinenucleosidesarereusedintheformationofpurinenucleotides.Thisiscalledsalvagepathway(salvagemeanspropertysavedfromloss).Salvagesynthesisrequiresfarlessenergythandenovosynthesis.
261.RNAwhichcontainscodonforspeicific aminoacid? a)tRNA b)rRNA c)mRNA d)None CorrectAnswer-CAns.is'c'i.e.,mRNAThemRNAcarriesgeneticinformationintheformofcodons.Codonsareagroupofthreeadjacentnucleotidesthatcodefortheaminoacidsofprotein.EachmRNAmoleculeisatranscriptofantisenseortemplatestrandofaparticulargene.Itsnucleotidesequenceiscomplementarytothatofantisenseortemplatestrandofthegene,i.e.adenineforthyamine,guanineforcytosine,uracilforadenine(asRNAdoesnotcontainthymine)andcytosineforguanine.Forexample,ifantisensestrandofDNAhasagenewithsequence5'-TTACGTAC-3',itscomplementaryRNAtranscriptwillbe5'-GUACGUAA-3'.
262.Glycineisrequiredinformationofall except? a)Heme b)Purines c)Glutathione d)Thyroxine CorrectAnswer-DAns.is'd'i.e.,ThyroxineGlycinelycineisanonessentialaminoacidwhichissynthesizedfromserine.Glycineismetabolizedbyfollowingthreepathways-Itcanbeconvertedtoserine,areactionthatrequiretetrahydrofolate(derivativeoffolicacidandpyridoxalphosphateascoenzyme.FurtherserineismetabolizedbyserinedehydrataseintopyruvateandNH4+.ThemajorpathwayofglycinedegradationisoxidativecleavageintoCO,andNH:byglycinecleavagecomplexofliver.H4folateisrequiredwhichisconvertedtoN5,N10-methyleneH4folate.Thusfolicacidisrequiredforglycinemetabolism.Glycinemaybeoxidativelydeaminatedbyglycineoxidasetoglyoxylicacid.Glycineisnecessaryfortheformationoffollowingproducts:-Heme,purinering,bileacidsconjugation(formationofglycocholicacid,andglyco-chenodeoxycholicacid),creatine,glutathione,glucose(bygluconeogenesis).
263.Trueaboutglycolysisareallexcept? a)Providenutritiontocancercells b)Substratelevelphosphorylationatpyruvatekinase c)Twocarbonendproductisformed d)NADPHisformedbyglyceraldhyde-3-phosphate dehydrogenase CorrectAnswer-CAns.is'c'i.e.,TwocarbonendproductisformedImportantfactsaboutglycolysisAnimportantbiochemicalsignificanceistheabilityofglycolysistoprovideATPintheabsenceofoxygen(anerobicglycolysis)andallowstissuestosurviveanoxicepisodes.Itoccursincytosol3Carbonatomsendproduct(pyruvateorlactate)isproduced.Irreversiblestepsarecatalyzedby:-Glucokinase/Hexokinase,phosphofructohnase-I,andpyruvatekinase.Reversiblestepsarecatalyzedby:-Phosphohexoseisomerase,aldolase,phosphotrioseisomerase,glyceraldehyde3-phosphatedehydrogenase,Phosphoglyceratekinase,Phosphoglyceratemutase,Enolase.Energy(ATP)usingstepsarecatalyzeeby:-Hexokinase/glucokinase,phosphofurctokinase.Energy(ATP)productionatsubstratelevelarecatalyzedby:Phosphoglyceratekinase,Pyruvatekinase.Reducingequivalent(NADH)productioniscatalyzedby:Glyceraldehyde3-phosphatedehydrogenase.Cancercellsderivenutritionfromglycolysisastheyhavelackof02supplybecauseoflackofcapillarynetwork.Glycolysis(anaerobic
glycolysis)istheonlymetabolicpathwayinthebodywhichcanprovideenergybyglucosemetabolisminanerobicconditions.
264.Instantenergytomuscleisprovidedby whichpathway? a)HMPshunt b)Embdenmayerhoffpathway c)Coricycle d)TCAcycle CorrectAnswer-BAns.is'b'i.e.,EmbdenmayerhoffpathwayATPandcreatinephosphateprovideimmediateenergy..Anaerobicglycolysis(EMP)providesearlyenergy.
265.Whichsteroidisformedfromcholesterol withouthydroxylation? a)Progesterone b)Glucocorticoid c)Mineralocorticoid d)Estradiol CorrectAnswer-AAns.is'a'i.e.,ProgesteroneProgesteroneisformedbeforehydroxylationstep.
266.Notobtainedfromplantsource? a)Cobalamine b)Riboflavin c)Thiamine d)VitaminA CorrectAnswer-AAns.is'a'i.e.,CobalamineVitaminB12(cobalaminorcynocobalmin)ispresentonlyinfoodofanimalorigin.Otherthreevitaminscanbetakenfromplantsource.
267.Pseudouridinefoundin? a)DNA b)rRNA c)mRNA d)tRNA CorrectAnswer-DAns.is'd'i.e.,tRNAModifiedbasesfoundintRNAare- 1. Dihydrouridine(D)inwhichoneofthedoublebondsofthebaseis reduced. 2. Ribothymidine(T)inwhichmethylgroupisaddedtouraciltoform thymine.Thus,tRNAistheonlyRNAthatcancontainthyminethoughonlysometimes. 3. Pseudouridine(yr)inwhichuracilisattachedtoribosebyacarbon- carbonbondratherthananitrogenbond.
268.Fattyacidsusedbyallexcept? a)Liver b)Muscle c)Brain d)Kidney CorrectAnswer-CAns.is`c'i.e.,BrainThereisnostoredfuelinbrain,butitutilized60%oftotalenergyunderrestingconditions.Glucoseisvirtuallythesolefuelforthebrain,exceptinprolongedstarvingwhenketonebodiesarethemajorsource.Fattyacidsdonotserveasfuelforthebrain,becausetheyareboundtoalbumininplasma;hencecannotcrossblood-brainbarrier.
269.VitaminnotrequiredinTCAcycle? a)Niacin b)Riboflavin c)Thiamine d)Folicacid CorrectAnswer-DAns.is'd'i.e.,FolicacidFouroftheBvitaminsareessentialinthecitricacidcycle: 1. Riboflavin,intheformofflavinadeninedinucleotide(FAD),a cofactorforsuccinatedehydrogenase. 2. Niacin,intheformofnicotinamideadeninedinucleotide(NAD)the electronacceptorforisocitratedehydrogenase,a-ketoglutaratedehydrogenase,andmalatedehydrogenase. 3. Thiamine(vitaminB1),asthiaminediphosphate,thecoenzymefor decarboxylationina-ketoglutaratedehydrogenasereaction. 4. Pantothenicacid,aspartofcoenzymeA,thecofactorattachedto "active"carboxylicacidresiduessuchasacetyl-CoAandsuccinylCoA.
270.Uricacidisformedby? a)Catabolismofproteins b)Catabolismofketones c)Catabolismofpurines d)Catabolismfopyrimidines CorrectAnswer-CAns.is'c'i.e.,Catabolismofpurines
271.Anaerobicglycolysisoccursinallplaces except a)Muscles b)RBCs c)Brain d)Kidney CorrectAnswer-CAns.is'c'i.e.,BrainTherearetwotypesofglycolysis:- 1. Aerobicglycolysis:-Itoccurswhenoxygenisplentifulandthefinal productispyruvate,i.e.,finalstepiscatalyzedbypyruvatekinase(seethecycleabove).WhichislaterconvertedtoacetylCoAbyoxidativedecarboxylation.Thereisnetgainof7ATPs.AcetylCoAentersTCAcycle. 2. Anaerobicglycolysis:-Itoccursintheabsenceofoxygen.The pyruvateisfermented(reduced)tolactateinsinglestage.ThereoxidationofNADH(formedintheglyceraldehyde-3-phosphatedehydrogenasestep)byrespiratorychainispreventedassameNADHisutilizedatlactatedehydrogenasestep.So,thereisnonetproductionofNADH.Thus,thereisnetgainof2ATPonly.UnlikepyruvatewhichisconvertedtoacetylCoAtoenterintokrebscycle,lactatecannotbefurtherutilizedbyfurthermetabolicpathways.Thus,lactatecanberegarededasdeadendinglycolysis.Anaerobicglycolysisoccursinexercisingskeletalmuscle,RBCs,lens,someregionofretina,renalmedulla,testisandleucocytes.
272.Sweatyfeetodorinurineisseenin? a)Phenylketonuria b)Maplesyrupurine c)Isovalericacidemia d)Alkaptonuria CorrectAnswer-CAns.is'c'i.e.,Isovalericacidemia"SweatyFeet"odourisseeninisovalericacidemia&glutaricaciduria"MousyorMustyOdour"ofskin,hairandurineisseeninPKU.BurntsugarlikeodourisseeninMSUdisease(Branchedchainketonuria).Boiledcabbagelikeurinaryodourisseenin-Tyrosinemia&hypermethioninemia.Swimmingpoolurineodourisseenin-Hawkinsinuria
273.Ketonebodiesarenotusedby? a)Muscle b)Brain c)RBC d)Renalcortex CorrectAnswer-CAns.is'c'i.e.,RBCOnlyglucoseisthesolefuelforRBCs.AsRBCshavenomitochondria,theyoxidizeglucoseanaerobicallytolactate.Liveralsocannotuseketonebodiesbecauseoflackofsuccinyl-CoA-acetoacetate-CoAtransferase,whichisrequiredforactivationofketonebodies.
274.Whichcollagenproducessheets? a)I b)II c)IV d)VI CorrectAnswer-CAns.is'c'i.e.,IVVariousstructureproducedbycollagens Fibrils Sheets Beadedfilaments Anchoringfibrils CollagenI CollagenIV CollagenVI CollagenVII CollagenII CollagenVIII CollagenIII CollagenX CollagenV CollagenXI
275.Theenergyforglycogenesisisprovided by- a)GTP b)GDP c)UTP d)AMP CorrectAnswer-CAns.is'c'i.e.,UTP
276.ThefunctionofvitaminKlargely dependsonwhichmineral? a)Selenium b)Calcium c)Iron d)Magnesium CorrectAnswer-BAns.is'b'i.e.,CalciumVitaminKplaysanimportantroleinbloodcoagulationforitisrequiredforthepost-translationalprocessingofseveralclottingfactors(factorII,VII,IXandX).Maturationoftheseclottingfactorsrequirestheconversionofglutamylresiduesofprecursorproteinsinto'ycarboxyglutamate(Gla)residuesbyadditionofcarboxylategroup.ThiscarboxylationofglutamylresdiueisvitaminKdependent.They-carboxyglutamate(Gla)residuessoformedserveasbindingsiteforcalciumions.EachGlacontainstwonegativechargeswhichchelatethepositivecalciumion.AfterbindingtoGlaresidueonactivatedclottingfactor,calciumbindswithnegativelychargedphospholipidspresentontheplateletcellmembrane.Inthisway,bridgingofthephospholipidstheGlaresidueofprothrominoccursviacalciumion.
277.Aminoacidwithaliphaticsidechainis? a)Serine b)Leucine c)Threonine d)Aspartate CorrectAnswer-BAns.'B'LeucineBasedonthechemicalstructureofsidechain,aminoacidsareclassifiedinto?Aliphaticaminoacids:-Alanine,glycine,isoleucine,leucine,valine.Hydroxyaminoacids:-serine,threonine,tyrosine.Sulfur-containingaminoacids:-Cysteine,methionine.Dicarboxylicaminoacids:-Asparticacid(aspartate),glutamicacid(glutamate).Amidecontainingaminoacids:-Glutamine,aspargine(theseareamidesofdicarboxylicaminoacids.Glutamineisanamideofglutamicacidandaspargineisanamideofasparticacid).Aromaticaminoacids:-Phenylalanine,tyrosine,tryptophan.Iminoacidsorheterocyclicaminoacids:-Oneofthe20aminoacids,prolineisanimino(-NH)acidnotanamino(-NH)acid,asareother19.
278.AccordingtoIUBsystem,hydrolases belongtowhichclass? a)EC-1 b)EC-2 c)EC-3 d)EC-4 CorrectAnswer-CAns.is'c'i.e.,EC-3 IUBclassification Enzymecodenumber(ECnumber) EnzymeEC-1 Oxidoreductase EC-2 Transferase EC-3 Hydrolases EC-4 Lyases EC-5 Isomerases EC-6 Ligases
279.Whichofthefollowingisserineprotease ? a)Pepsin b)Trypsin c)Carboxypeptidase d)None CorrectAnswer-BAns.is'b'i.e.,Trypsin
280.Reducingequivalantsproducedin glycolysisaretransportedfromcytosoltomitochondriaby? a)Carnitine b)Creatine c)Malateshuttle d)Glutamateshuttle CorrectAnswer-CAns.is'c'i.e.,MalateshuttleMostoftheNADHandFADH2,enteringthemitochondrialelectrontransportchainarisefromcitricacidcycleand13-oxidationoffattyacids,locatedinthemitochondriaitself.However,NADHisalsoproducedinthecytosolduringglycolysis.Togetoxidized,NADHhastobetransportedintothemitochondriaasrespiratorychain(ETC)islocatedinsidethemitochondria.Since,theinnermitochondrialmembraneisnotpermeabletocytoplasmicNADH,therearespecialshuttlesystemswhichcarryreducingequivalentsfromcytosolicNADH(ratherthanNADHitself)intothemitochondriabyanindirectroute.Twosuchshuttlesystemsthatcanleadtotransportofreducingequivalentfromthecytoplasmintomitochondriaare:- 1. Malateshuttle(malate-aspartateshuttlesystem).2. Glycerophosphateshuttle.
281.HMPshuntoccursinallorgansexcept? a)Liver b)Adiposetissue c)RBC d)Brain CorrectAnswer-DAns.is'd'i.e.,BrainHMPisanalternativeroutefortheoxidationofglucose(besideglycolysis).Itisalsocalledas"pentosephosphatepathway","Dickens-Horeckerpathway","Shuntpathway"or"phosphogluconateoxidativepathway".HMPshuntisrequiredforprovisionofreducedNADPHandfiver-carbonsugars(Pentosephosphates)fornucleicacidsynthesis.Normally,90%ofglucoseisoxidizedbyglycolysisand10%isoxidizedbyHMPshunt.However,inliverandRBCsHMPshuntaccountsforoxidationof30%glucose.HMPshuntoccursinthecytosol.Itishighlyactiveinliver,adiposetissue,adrenalcortex,lens,cornea,lactating(butnotthenonlactating)mammaggland,Gonads(testis,ovary)anderythrocytes.Activityofthispathwayisminimalinmuscleandbrain,wherealmostalloftheglucoseisdegradedbyglycolysis.
282.Fastestactingenzyme? a)LDH b)Trypsin c)Catalase d)None CorrectAnswer-CAns.is'c'i.e.,CatalaseMeasurementofenzymeactivityTheactivityofenzymeismeasuredintermsofthefollowing:Unitofenzymeactivity:-Byinternationalagreement,oneunitenzymeactivityisdefinedastheamountcausingtransformationof1.0micromoleofsubstrateperminuteat25?C.Itisusuallyexpressedasmoleofsubstratedisappearedormoleofproductformedperminute.Specificactivity:-Itreferstothenumberofenzymeunitspermilligramofprotein.Itisameasureofenzymepurity;highertheenzymepurity,moreisthespecificactivity.Turnovernumber:-Thisreferstothenumberofsubstratemoleculestransformedperunittimebyasingleenzymemolecule(orbyasinglecatalyticsite),whentheenzymeconcentrationaloneisrate-limitingfactor.Catalasehasthehighestturnovernumberandhenceisthefastestactiveenzyme.Carbonicanydrasehasthe2"fastestturnovernumber;therefore,itis2ndfastestactiveenzyme(aftercatalase).Lysozymehasthelowestturnovernumberandthereforeisslowestacting.
283.Inhibitionofglycolysisbyincreased supplyof02iscalled? a)Crabtreeeffect b)Pasteureffect c)Lewiseffect d)None CorrectAnswer-BAns.is'b'i.e.,PasteureffectPasteureffectIthasbeenobservedthatunderanaerobicconditionatissueormicroorganismutilizesmoreglucosethanitdoesunderaerobicconditions.Itreflectsinhibitionofglycolysisbyoxygenandiscalledpasteureeffect.ThePasteureffectisduetoinhibitionoftheenzymephosphofructokinasebecauseofinhibitoryeffectcausedbycitrateandATP,thecompoundsproducedinpresenceofoxygenduetooperationofTCAcycle.CrabtreeeffectThisisoppositeofPasteureffect,whichrepresentsdecreasedrespirationofcellularsystemscausedbyhighconcentrationofglucose.Whenoxygensupplyiskeptconstantandglucoseconcentrationisincreased,theoxygenconsumptionbycellsfalls,i.e.,relativeanaerobiosisisproducedwhenglucoseconcentrationisincreasedinconstantsupplyofoxygen.Itisseenincellsthathaveahighrateofaerobicglycolysis.InsuchcellstheglycolyticsequenceconsumesmuchoftheavailablePiandNAD+,whichlimitstheiravailabilityforoxidative
phosphorylation.Asaresult,rateofoxidativephosphorylationdecreases,andoxygenconsumptionalsoshowsacorrespondingfall.
284.RNAispresentin? a)Cytoplasm b)Nucleus c)Ribosome d)Alloftheabove CorrectAnswer-DAns.is`d'i.e.,AlloftheabovemRNAissynthesizedfromDNAbytheprocessoftranscriptioninthenucleus.AfterformationmRNAtransportoutofthenucleusintocytoplasm.t-RNAisalsosynthesizedinnucleusandistransportedtocytoplasm.Proteinsynthesis(translation)occursinribosomes,andrequiresbothmRNAandtRNA.rRNAispresentinribosomes.rRNAissynthesizedinnucleolusThus,RNAcanbefoundin- 1. Nucleus2. Cytoplasm3. Ribosome4. Nucleolus
285.Allarereducingsugarsexcept- a)Sucrose b)Lactose c)Glucose d)Fructose CorrectAnswer-AAns.A.Sucrose Disaccharides SugarUnits Linkage Trehalose(Sugarof DGlucose+ 1-------1linkage insecthemolymph, DGlucoseyeastandfungi)Sucrose(CaneSugar) DGlucose 1-------2 +DFructose linkage
286.Reducingsugarinurinecanbedetected by- a)a)Benedictstest b)b)Fehlingsolution c)c)Glucose-oxidasetest d)d)Alloftheabove CorrectAnswer-DExplanation-Reducingsugarcanbedetectedby-benedict'stest,fehling'stest,gluco-oxidasetest.
287.Substratelevelphosphorylationisby a)Pyruvatekinase b)Phosphofructokinase c)Hexokinase d)ATPsynthase CorrectAnswer-AAns.'A'PyruvatekinaseSubstrateLevelPhosphorylation-InGlycolysis-PhosphoglyceratekinasePyruvatekinaseInCitricAcidCycle-Succinatethiokinase
288.TypeVIglycogenstoragediseaseisdue tothedeficiencyof? a)Musclephosphorylase b)Glucose-6-phosphatase c)Liverphosphorylase d)Branchingenzyme CorrectAnswer-CTypeVIglycogenisalsocalledHer'sdiseaseanditiscausedbyenzymedefectliverphosphorylase. Clinicalfeaturesarehepatomegaly,accumulationofglycogenintheliverandmildhypoglycemia.
289.Xanthoproteicreactioninvolves- a)Carbolicacid b)H2SO4 c)HCL d)Nitricacid CorrectAnswer-DAns.'D'NitricacidXanthoproteictest:Theringsystemsinphenylalanine,tyrosineandtryptophanundergonitrationontreatmentwithconcentratednitricacidwhenheated.Theendproductisyellowincolorwhichisintensifiedinstrongalkalinemedium.Thisreactioncausestheyellowstainintheskinbynitricacid.
290.Coenzymenotrequiredinformationof glutamate- a)Thiaminepyrophosphate b)Pyridoxialphosphate c)Niacin d)Noneoftheabove CorrectAnswer-AAns.'A'ThiaminepyrophosphateNAD+isderivedfromnicotinicacid,amemberofthevitaminBcomplex,usedinthesynthesisofGABA.Duringtransaminationreactionglutamateisformed.PyridoxalPhosphateactsasacoenzyme.
291.Zewellgersyndroneisduetoabsenceof a)Lysosomal b)Mitochondria c)Peroxisome d)Nucleus CorrectAnswer-CAnswer.C.PeroxisomeZellwegersyndrome,alsocalledcerebrohepatorenalsyndrome,isararecongenitaldisordercharacterizedbythereductionorabsenceoffunctionalperoxisomesinthecellsofanindividual.Zellwegersyndromeisassociatedwithimpairedneuronalmigration,neuronalpositioning,andbraindevelopment.Inaddition,individualswithZellwegersyndromecanshowareductionincentralnervoussystem(CNS)myelin(particularlycerebral),whichisreferredtoashypomyelination.
292.Urea,creatinine,nitricoxideformedby whichaminoacid a)Histidine b)Glycine c)Cysteine d)Arginine CorrectAnswer-DAnswer:D.ArginineArginine,asemiessentialorconditionallyessentialaminoacidinhumans,isoneofthemostmetabolicallyversatileaminoacids.Itservesasaprecursorforthesynthesisofurea,nitricoxide,polyamines,proline,glutamate,creatine,andagmatine.
293.Whichofthefollowingisnotthesource ofcytosolicNADPH? a)Isocitratedehydrogenase b)ATPcitratelyase c)Malicenzyme d)G6PD CorrectAnswer-BAnswer.B.ATPcitratelyaseNADPHisacofactorusedinanabolicreactions,suchaslipidandnucleicacidsynthesis,whichrequireNADPHasareducingagent.ThemajorsourceofNADPHinanimalsandothernon-photosyntheticorganismsisthepentosephosphatepathway.Thekeyenzymesintheseprocessesare:NADP-linkedmalicenzyme,NADP-linkedisocitratedehydrogenase,NADP-linkedglutamatedehydrogenaseandnicotinamidenucleotidetranshydrogenase.
294.Allaretrueregardingmitochondrial DNA,EXCEPT? a)Doublestranded b)Inheritedfrommother c)Highmutationrate d)Allrespiratoryproteinsaresynthesizedwithinmitochondria itself CorrectAnswer-DAnswer.D.AllrespiratoryproteinsaresynthesizedwithinmitochondriaitselfMtDNAisorganizedasacircular,covalentlyclosed,double-strandedDNA.Insexualreproduction,mitochondriaarenormallyinheritedexclusivelyfromthemother;themitochondriainmammalianspermareusuallydestroyedbytheeggcellafterfertilization.MutationsofmitochondrialDNAcanleadtoanumberofillnessesincludingexerciseintoleranceandKearns?Sayresyndrome(KSS),whichcausesapersontolosefullfunctionofheart,eye,andmusclemovements.
295.Whichapolipoproteinisresponsiblefor Alzeihmersdisease a)APOE4 b)APOE3 c)APOE2 d)APOE1 CorrectAnswer-AANSWER.A.APOE4ThreecommonpolymorphismsintheAPOEgene,e2,e3,ande4,resultinsingleaminochangesintheApoEprotein.Thee4alleleofapolipoproteinE(APOE)isthemajorgeneticriskfactorforAlzheimer'sdisease(AD).thedifferentialeffectsofapoEisoformsonA?aggregationandclearanceplaythemajorroleinADpathogenesis.Inparticular,APOEe4isassociatedwithincreasedriskforAD,whereasAPOEe2isassociatedwithdecreasedrisk.
296.HyperammonaemiainhibitTCAcycleby depleting? a)succinate b)aketoglutarate c)malate d)fumarate CorrectAnswer-BAnswer:B.aketoglutarateTheureacycleandthecitricacidcycleareindependentcyclesbutarelinked.Todetoxifyammoniainhyperammonemia,moreglutamateisrequired.Thisglutamateisformedfromc-ketoglutarate.a-ketoglutarate?Transamination?glutamate+NH4+?glutamine.Thusexcessivea?ketoglutarateisconsumedleadingtodecreaseavailabilityofa?ketoglutarateforTCAcycle
297.whichaminoacidisusedtosynthesise Nitricoxide? a)glycine b)arginine c)tyrosine d)threonine CorrectAnswer-BANSWER:B.ArginineNitricoxideisproducedbyagroupofenzymescallednitricoxidesynthases.Theseenzymesconvertarginineintocitrulline,producingNOintheprocess.OxygenandNADPHarenecessaryco-factors.threedistinctgenesencodeNOSisozymes:neuronal(nNOSorNOS-1),cytokine-inducible(iNOSorNOS-2)andendothelial(eNOSorNOS-3)
298.Menkesdiseaseisassociatedwithwhich enzymedeficiency. a)lysyloxidase b)Methioninesynthase c)Glutamylaminopeptidase d)Lysylhydroxylase CorrectAnswer-AAnswers:A.lysyloxidaseOneoftheenzymes,lysyloxidase,requirescopperforproperfunction.Thisenzymecross-linkstropocollagenintostrongcollagenfibrils.Menkesdisease(MNK),alsoknownasMenkessyndrome,isanX-linkedrecessivedisordercausedbymutationsingenescodingforthecopper-transportproteinATP7A,leadingtocopperdeficiency.Thedecreasedsupplyofcoppercanreducetheactivityofnumerouscopper-containingenzymes.Thesearenecessaryforthestructureandfunctionofbone,skin,hair,bloodvesselsandthenervoussystemsuchaslysyloxidase.
299.LCATdeficiencyincreasesthefollowing a)HDL b)LDL c)VLDL d)Chylomicron CorrectAnswer-AAnswer:A.HDLLecithincholesterolacyltransferasedeficiency(LCATdeficiency)isadisorderoflipoproteinmetabolism.AdeficiencyofLCATcausesaccumulationofunesterifiedcholesterolincertainbodytissues.CholesteroleffluxesfromcellsasfreecholesterolandistransportedinHDLasesterifiedcholesterol.LCATistheenzymethatesterifiesthefreecholesterolonHDLtocholesterolesterandallowsthematurationofHDL.LCATistheenzymethatesterifiesthefreecholesterolonHDLtocholesterolesterandallowsthematurationofHDL.LCATdeficiencydoesnotallowforHDLmaturationresultinginitsrapidcatabolismofcirculatingapoA-1andapoA-2.TheremainingformofHDLresemblesnascentHDL.
300.A25yearoldalcoholicpresentedwith edema,hypertension,oculardisturbance,andchangesinmentalstatewasobserved,diagnosisofhighoutputcardiacfailurewasmadewithWetBeriBeri,thisisduetodeficiencyof? a)VitB3 b)VitB6 c)VitB9 d)VitB1 CorrectAnswer-DAnswer:D.VitB1Wetberiberiisthetermusedforthiaminedeficiencywithcardiovascularinvolvement.Inthefirststage,peripheralvasodilationoccurs,leadingtoahighcardiacoutputstate.Thisleadstosaltandwaterretentionmediatedthroughtherenin-angiotensin-aldosteronesysteminthekidneys.Amorerapidformofwetberiberiistermedacutefulminantcardiovascularberiberi,orShoshinberiberi.Thepredominantinjuryistotheheart,andrapiddeteriorationfollowstheinabilityoftheheartmuscletosatisfythebody'sdemandsbecauseofitsowninjury.Inthiscase,edemamaynotbepresent.Instead,cyanosisofthehandsandfeet,tachycardia,distendedneckveins,restlessness,andanxietyoccur.
301.GlutamineisIncreaseinCSF,bloodand urine,thisisduetodeficiencyof a)CPS-I b)Arginase c)OTC d)Argininosuccinatesynthetase CorrectAnswer-AAnswer:A.CPS-ICPSIdeficiencyisoneoftheproximalureacycledefectsandisduetoacompleteorpartialdeficiencyofthemitochondrialenzymecarbamylphosphatesynthetaseI(CPSI)whichproducescarbamylphosphatefromammonia,ATP,andHCO3.CarbamoylphosphatesynthetaseI(CPS1orCPSI)transfersanammoniamoleculefromglutamineorglutamatetoamoleculeofbicarbonatethathasbeenphosphorylatedbyamoleculeofATP.TheresultingcarbamateisthenphosphorylatedwithanothermoleculeofATP.Theresultingmoleculeofcarbamoylphosphateleavestheenzyme.CPS-Iistheratelimiting(pacemaker)enzymethispathway.CPS-IisactiveonlyinthepresenceofN-AcetylGlutamate,anallostericactivator.
302.Trueabouttype1diabetesmellitus a)Decreasedproteincatabolism b)DecreasedhepaticGlucoseoutput c)Increasedlipolysis d)Increaseglucoseuptake CorrectAnswer-CAnswer:C.IncreasedlipolysisUncontrolledinsulin-dependentdiabetesmellitus(typeIdiabetes)involvesdecreasedglucoseutilization,withhyperglycemia,andincreasedfattyacidoxidation.Increasedfattyacidoxidationleadstoexcessiveproductionofacetoaceticand3-hydroxybutyricacidsandofacetone,whichareknownasketonebodies.2.Acetoaceticand3-hydroxybutyricacidsdissociateatbodypHandreleaseHleadingtoametabolicacidosis.LCATistheenzymethatesterifiesthefreecholesterolonHDLtocholesterolesterandallowsthematurationofHDL.LCATdeficiencydoesnotallowforHDLmaturationresultinginitsrapidcatabolismofcirculatingapoA-1andapoA-2.TheremainingformofHDLresemblesnascentHDL.
303.ProteinwhichisnotsynthesisedInliver is a)Phaseprotein b)Immunoglobulins c)Albumin d)Plasmahormone CorrectAnswer-BAnswer:B.ImmunoglobulinsTheliverservesseveralmetabolicfunctionswithinthebodyincludingproteinsynthesisandmetabolism.Theliverisresponsibleforanarrayofproteins.ImmunoglobulinsaresynthesisedinplasmacellswhicharebelievedtobeendproductsofthedifferentiationofcellscalledB-lymphocytes.Theliverplaysacrucialroleintheproductionofnearlyallplasmaproteins(albumin,alpha-1-acidglycoprotein,majorityofcoagulationcascade,andfibrinolyticpathways).Notableexceptionsinclude:globulins,factorIII,IV,VIII.Proteinsproducedbytheliver:proteinS,proteinC,proteinZ,plasminogenactivatorinhibitor,antithrombinIII.VitaminKdependentproteinssynthesizedbytheliverinclude:FactorsII,VII,IX,andX,proteinSandC.
304.typeofcholesterolpresentin gallstones? a)Amorphouscholesterolmonohydrate. b)Amorphouscholesteroldihydrate. c)CrystallineCholesteroldihydrate. d)Crystallinecholesterolmonohydrate. CorrectAnswer-DAnswer:D.Crystallinecholesterolmonohydrate.Gallstonesarehardeneddepositsofdigestivefluidthatcanforminyourgallbladder.Themostcommontypeofgallstone,calledacholesterolgallstone,oftenappearsyellowincolor.Thesegallstonesarecomposedmainlyofundissolvedcholesterol.Precipitationofsolidcholesterolcrystalsfromsupersaturatedbilehasanessentialroleincholesterolgallstoneformation.Gallstonesarecomposedprincipallyofcholesterolmonohydratecrystals(cholesterolstones)ortheacidsaltofcalciumbilirubinate(pigmentstones).Whenbileisconcentratedinthegallbladder,itcanbecomesupersaturatedwiththesesubstances,whichthenprecipitatefromthesolutionasmicroscopiccrystals.Thecrystalsaretrappedingallbladdermucus,producinggallbladdersludge.
305.collagenpresentinskinis a)TypeII b)TypeI c)TypeIII d)TypeIV CorrectAnswer-BAnswer:B.TypeICollagenisaproteinthatispartofcartilage,bone,andothertissuesinanimalsandhumans.Asthemaincomponentofconnectivetissue,itisthemostabundantproteininmammals.Collagenconsistsofaminoacidswoundtogethertoformtriple-heliceslofelongatedfibrils.Itis,mostly,foundinfibroustissuessuchastendons,ligaments,andskin.Sofar,28typesofcollagenhavebeenidentifiedanddescribed.Thefivemostcommontypesare:TypeI:skin,tendon,vasculature,organs,bone(maincomponentoftheorganicpartofbone)TypeII:cartilage(maincollagenouscomponentofcartilage)TypeIII:reticulate(maincomponentofreticularfibers),commonlyfoundalongsidetypeI.TypeIV:formsbasallamina,theepithelium-secretedlayerofthebasementmembrane.TypeV:cellsurfaces,hair,andplacenta
306.whichofthefollowingisnotRibozyme? a)PloyApolymerase b)Ribonuclease c)Transpeptidase d)PeptidylTransferase CorrectAnswer-AAnswer:A.PloyApolymerasePolyadenylationistheadditionofapoly(A)tailtoamessengerRNA.Thepoly(A)tailconsistsofmultipleadenosinemonophosphates;inotherwords,itisastretchofRNAthathasonlyadeninebases.polyadenylationispartoftheprocessthatproducesmaturemessengerRNA(mRNA)fortranslation.It,therefore,formspartofthelargerprocessofgeneexpression.
307.Type-Ihyperlipoproteinemiais characterizedby a)ElevatedLDL b)ElevatedHDL c)Elevatedchylomicrons d)Elevatedlipoproteinlipase CorrectAnswer-CAnswerC.ElevatedchylomicronsLipoproteinlipasedeficiency(TypeIhyperlipoproteinemia)resultsinincreasedlevelofchylomicrones.Lipoproteinlipasedeficiencyisageneticdisorderinwhichapersonhasadefectivegeneforlipoproteinlipase,whichleadstoveryhightriglycerides,whichinturncausesstomachpainanddepositsoffatundertheskin,andwhichcanleadtoproblemswiththepancreasandliver,whichinturncanleadtodiabetes.Thedisorderonlyoccursifachildacquiresthedefectivegenefrombothparents(itisautosomalrecessive).Itismanagedbyrestrictingfatindiettolessthan20g/day.Thediseaseoftenpresentsininfancywithcolickypain,failuretothrive,andothersymptomsandsignsofthechylomicronemiasyndrome.Theconditionhasalsobeencalledfamilialchylomicronemiasyndrome,chylomicronemia,chylomicronemiasyndrome.andhyperlipoproteinemtypeIa.
308.InKreb'scycleandUreacyclethelinking aminoacidis a)Fumarate b)Alanine c)Arginine d)Aspartate CorrectAnswer-DAnswer:D.AspartateAspartatehelpsincondensationwithcitrullinetoformarginosuccinicacid.ArginosuccinicacidundergoesalyticreactiontoformArginineandfumarate.oxaloacetate,theketoacidobtainedfromaspartateisintermediateofTCAcycle.HenceaspartateisacommonintermediateofTCAcyclethroughoxaloacetateandureacycle(directly)
309.ThecofactorvitaminB12isrequiredfor thefollowingconversion: a)DopaminetoNorepinephrine b)PropionylCoAtomethylmalonylCoA c)MethylmalonylCoAtosuccinylCoA d)Cysteinetohomocysteine CorrectAnswer-CAns:C.MethylmalonylCoAtosuccinylCoA(Ref:Harper30/ep550,558,28iep346)VitaminB12asCofactorfor:MethylmalonylCoAmutase-Isomerizationofmethylmalonylco-Atosuccinylco-A.Methioninesynthase-Methylationofpyrimidineringtoformthymine.Homocysteinemethyltransferase-MethylationofhomocysteinetomethionineMetabolismofdiol.Inbacteriaforinterconversionofglutamate&beta-methylaspartate?
310.Whichofthefollowingenzymeactivity decreasesinfasting? a)Hormonesensitivelipase b)Glycogenphosphorylase c)AcetylCoACarboxylase d)PhosphofructokinaseI CorrectAnswer-DAns:D.PhosphofructokinaseIAns:D.PhosphofructokinaseIPhosphofructokinase1(PFK1)providesthefirstenzymaticstepatwhichaglucosemoleculebecomescommittedtoglycolysisandthereforeissubjecttoregulation(Nelson&Cox,2008).PFK1activitydependsontheconcentrationsofAMP,ADP,andATPwithallostericactivationbyAMPandADPandallostericinhibitionbyATP.Inthefastingstate,glucagoncausesthelivertomobilizeglucosefromglycogen(glycogenolysis)andtosynthesizeglucosefromoxaloacetateandglycerol(gluconeogenesis).GlucagonstimulatesanincreaseincAMP,leadingtoanincreaseinphosphorylationbyproteinkinaseA.Thewaveofphosphorylationthatspreadsthroughthelivercellactivatesenzymessuchasglycogenphosphorylasethatareinvolvedinglycogendegradationwhilesimultaneouslyinhibitingglycogensynthesis.Inhibitionofglycogensynthasepreventsfutileresynthesisofglycogenfromglucose1-phosphate(G1P)viaUDP-Glc.Glucose-6-phosphatase(G6Pase),agluconeogenicenzymethatispresentintheliverbutnotinmuscle,thenconvertsG6Ptoglucoseforrelease
intotheblood.Ref:Harper'sillustratedbiochemistry,3a,ed.,pg.I88andLippincott'sillustratet!reviewsr6't'ed.,pg.107
311.Whichmicronutrientdeficiencycauses anemia? a)Copper b)Molybdenum c)Selenium d)Flurine CorrectAnswer-AAns.is'a'i.e.,CopperCoppercontainingproteinceruloplasminisnecessaryfortransportofironintheFerricformacrossmembranesCopperisanintegralcomponentofALAsynthase,whichisnecessaryforhemesynthesisCopperhelpsintheuptakeofironacrossnormoblasts
312.Trueaboutsigmafactor? a)Subunitof50sribosome b)SubunitofDNApolymerase c)SubunitofRNApolymerase d)InitiatesDNAreplication CorrectAnswer-CAns-'C'SubunitofRNApolymeraseThebasicDNA-dependentRNApolymeraseofthebacteriumEscherichiacoliexistsasanapproximately400-kDacorecomplexconsistingoftwoidenticalsubunits,twolarge,andsubunits,andasubunit.ThecoreRNApolymerase,2,oftentermedE,associateswithaspecificproteinfactor(thesigma[]factor)toformholoenzyme,2,orE.Sigmafactorshaveadualroleintheprocessofpromoterrecognition;associationwithcoreRNApolymerasedecreasesitsaffinityfornon-promoterDNA,whilesimultaneouslyincreasingholoenzymeaffinityforpromoterDNA.
313.InETC,cyanideinhibits? a)ComplexI b)CytochromeCoxidase c)ComplexIV d)ComplexIII CorrectAnswer-B:CAns.is'b'i.e.,CytochromeCoxidase&'c'i.e.,ComplexIV[RefHarper29th/ep.127,28th/ep.108,109;Vasudevan6thlep.234]*ComplexI:-Barbiturates(amobarbital),piercidinA,rotenone,chlorpromazine,guanithidine.*ComplexII:-Carboxin,TTFA,malonate.*ComplexIII:-Dimercaprol,BAL,actinomycinA,Naphthyloquinone.*ComplexIV(cytochromecoxidase):-Carbonmonoxide(CO),cyanide(CN-),H2S,azide(N')
314.HHHsyndromeisduetodefectin? a)Tryptophanmetabolism b)Histidinetransporter c)BranchedchainAAmetabolism d)Ornithinetransporter CorrectAnswer-DAns.is'd'i.e.,Ornithinetransporter[RefTextbookofclinicalpaediatricsp.496]Hyperornithinaemia,hyperammonaemia,homocitrullinuria(HHH)syndromeisanautosomalrecessivedisorderofornithinetransportcausedbymutationsingeneSLC25A15encodingtheornithinetransorterprotein(ORNT1).Thereisdefectiveactivityoftheornithinetransporteracrossthemitochondrialmembrane,whichcausesafunctionaldeficiencyoftwomitochondrialenzymes:Ornithinetranscarbomylase:Whichcatalysesthecondensationofornithineandcarbamoylphosphatetocitrulline.Ornithine-8-aminotransferase(OAT):Whichmetabolizestheornithineto.'-pyrroline-5-carboxylateandultimatelyglutamateandproline.Ornithineaccumulatesinthecytoplasmanditsdeficiencyinmitochondriacausesasecondaryureacycledisorderandhyperammonemia.Carbamoylphosphateaccumulatesandundergoesallternatemetabolismtoform: 1. Homocitrulline-Excretedinurine2. Oroticacid3. Plasma
315.EarliestsymptomofTaysachdisease a)Exaggeratedstartleresponse b)Bonedeformation c)Hepatomegaly d)Excessivebleeding CorrectAnswer-AAns.is'a'i.e.,Exaggeratedstartleresponse[RefIllustratedmedicalbiochemistryp.330]Tay-SachdiseaseClinicalsymptomsareusuallyevidentinthefirstyearoflifeInitialsignsarenotdramaticandpresentasenfeeblement,spasticityandslowdevelopment.Anexaggeratedstartleresponsetosoundmaybethemostsignificantearlysignofwhichaparentisaware.Otherfeaturesarementalretardation,deteriorationofvisionandearlydeath."Affectedinfantsusuallydevelopnormallyuntil4-5monthsofagewhendecreasedeyecontactandanexaggeratedstartleresponsetonoise(hyperacusis)arenoted."---Nelson.PatientswiththeinfantileformofTay-Sachsdiseasehaveclinicalmanifestationsininfancyincludinglossofmotorskills,increasedstartlereaction,andmacularpallorandretinalcherry-redspots.
316.Mostimportanttoolusedingenetic engineering a)Halicase b)Topoisomerase c)DNALigase d)Restrictionendonuclease CorrectAnswer-DAns.is'd'i.e.,Restrictionendonuclease[RefSatyanarayanp.579]Geneticengineeringsimplymeansmanipulationofgeneticmaterialtoachievethedesiredgoalinapredeterminedway.MostimportantmoleculartoolsingeneticengineeringareenzymesusedinrecombinantDNAtechnology.(alsocalledgeneticengineering).Mostimportantoftheseenzymesisrestrictionendonuclease.AttheheartofgeneticengineeringistheabilitytocutDNAmoleculesatpreciselydefinedsites.Thisisusuallydonewithpurifiedbacterialenzyme,therestricationendonuclease.
317.Chromosomalinstabilitysyndromeis a)Fanconisyndrome b)AtaxiaTelangectasia c)Bloomsyndrome d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,Alloftheabove[RefTalwarGPp.855]Chromosomalinstabilitysyndromesareagroupofdisorderscharacterizedbychromosomalinstabilityandbreakage.Thereare:1.Xerodermapigmentosa3.Fanconisyndrome2.Bloomsyndrome4.Ataxiatelangectasia
318.VitaminB1isrequiredforwhichreaction a)Transamination b)Oxidativedecarboxylation c)Carboxylation d)Alloftheabove CorrectAnswer-BAns.is'b'i.e.,Oxidativedecarboxylation[RefHarper29th/ep.534]*Activeform(coenzymeform)ofthiamineisthiaminepyrophosphate(TPP),alsocalledthiaminediphosphate(TDP).*TPPactsascoenzymefor-Oxidativedecarboxylation:-Pyruvatedehydrogenase,a-ketoglutaratedehydrogenase,brached-chainketoaciddehydrogenase.-TransketolaseinPPP.
319.Hyperammonemiatype-1isdueto deficiencyof a)Arginase b)Arginosuccinatelyase c)Arginosuccinatesynthase d)CPS-1 CorrectAnswer-DAns.is'd'i.e.,CPS-1[RefDineshPuri3'/ep.275]DisorderscausedbygeneticdefectsofureacycleenzymesHyperammonemiatype-IHyperammonemiatype-IICitrullinemiaArgininosuccinicaciduriaArgininemiaDefectiveenzymeCarbamoylphosphatesynthase-IOrnithinetranscarbamoylaseArgininosuccinatesynthaseArgininosuccinatelyaseArginaseProductsaccumulatedAmmoniaAmmoniaCitrullineArgininosuccinateArginine.
320.Majorsiteofproteinglycosylationis? a)ERandgolgibody b)Ribosomeandgolgibody c)ERandribosome d)Ribosomeandcytoplasm CorrectAnswer-AAns.is'a'i.e.,ERandgolgibody[RefHarper28aVep.514,515;Lippincotts5thlep.167,168]N-GlycosylationoccursinERandO-glycosylationoccursingolgiapparatus.
321.WhichisnotastepofPCR? a)Annealing b)Extension c)Transformation d)Denaturation CorrectAnswer-CAns.is'c'i.e.,Transformation[RefLippincott's5thlep.479-83;Harper28th/ep.395]StepsinPCRIsolationoftargetDNAsequencePrimerconstructionDenaturationofDNAAnnealingofprimerstosinglestrandedDNAChainextension.
322.Whichdoesnotplayaroleinprotein synthesis? a)Exon b)Intron c)m-RNA d)ATP CorrectAnswer-BAns.is'b'i.e.,Intron[RefLippincott's5tvep.426]Primarytranscriptcontainsintrons&exons.Splicingremovesintrons(segmentofgenethatisnotrepresentedinmaturem-RNA)fromprimarytranscript.SynthesisofproteinfrommRNAiscalledtranslation.Translationistheprocessbywhichribosomesconverttheinformation(geneticcode)carriedbymRNAtothesynthesisofnewprotein.Translationoccursinribosomes.BasicrequirementsfortranslationincludemRNA,tRNAs,ribosomes,energy(ATPandGTP),enzymes,andspecificproteinfactorslikeinitiationfactors,elongationfactorsetc.
323.Pyridoxinedeficiencyleadstoaltered metabolismof? a)Phenylalanine b)Tryptophan c)Methionine d)Tyrosine CorrectAnswer-BAns.is'b'i.e.,Tryptophan[RefDineshpuri3rdlep.378]Tryptophanloadtestisusedforpyridoxin.Inpyridoxin(vitaminB6)deficiency,xanturenicacidexcretionisincreasedaftergivingtryptophanloaddose.
324.Kcat/kmisameasureof- a)Enzymeefficiency b)Speedofenzymaticreaction c)Concentrationofsubstrate d)Enzymeturnover CorrectAnswer-DAnswer-D.Enzymeefficiency"TheKmofanenzymeistheconcentrationofthesubstratethatenablestheenzymetoFunctionathalfmaximumactivityandisthereforeameasureofthespecificityofasubstratefortheenzyme".Actuallyenzymespecificityisnotmeasuredbyalone.ItismeasuredbytheratioKcat/Kmwhichisasecondorderrateconstantforthereactionbetweensubstrateandfreeenzyme.Thisratioisimportant,foritprovidesadirectmeasureofenzymeeficiencyandspecificity.Note:Km,isturnovernumberandmeasurestJrerateofthecatalyticprocess
325.Enzymeinvolvedinthetransferof hydrogenionis a)Hydratase b)Oxidase c)Peroxidase d)Dehydrogenase CorrectAnswer-B:DAns.is'b'i.e.,Oxidase&'d'i.e.,Dehydrogenase[RefHarper30th/ep.198;Vasudevan5th/ep.210]Enzymeinvolvedinoxidation-reactionare:?CauseremovalofhydrogenDehydrogenases:UseNADorFADasacceptorOxidases:Useoxgenasacceptor,AddoxygenOxygenases
326.Whichofthefollowingisa constitutiveenzyme? a)Hexokinase b)Glucokinase c)pgalactosidase d)Cyclooxygenase-2 CorrectAnswer-AAns.is'a'i.e.,Hexokinase
327.Sequenceofcomplexesintheelectron transportchainis- a)NADHdehydrogenaseQCytochromebc1 Cytochromeaa3O, b)NADHdehydrogenaseQCytochromeaa3 CytochromebclO, c)NADHdehydrogenaseCytochromeaa3Q CytochromebclO, d)NADHdehydrogenaseCytochromebclQ Cytochromeaa3O, CorrectAnswer-AAns.is'a'i.e.,NADHdehydrogenaseQCytochromebclCytochromeaa302Electrontransportchainismadeupof5stationarycomplexesand2mobilecomplexes
328.Regardingenergyproductionbythe electrontransportchain,whichistrue? a)Thecomplexesarearrangedinadecreasingorderofredox potential b)Thecomplexesarearrangedinadecreasingorderofability togetreduced c)Thecomplexesarearrangedinadecreasingorderofstate ofoxidation d)Thecomplexesarearrangedinadecreasingorderof energylevel CorrectAnswer-DAns.is'd'i.e.,Thecomplexesarearrangedinadecreasingorderofenergylevel[RefEssentialofbiochemistryp.712]ETChelpinATPgenerationItisexplainedbyMitchell'schemiosmotictheory.Accordingtothistheory,thecomplexesarearrangedinanincreasingorderofredoxpotential.Redoxpotentialisameasureofabilitytogetreduced.Sothecomplexesarearrangedinanincreasingorderofabilitytogetreduced.Asmoreasubstanceisoxidisedhigherwillbetheabilitytogetreduced,thecomplexesarearrangedinanincreasingorderofstateofoxidation.Asstateofoxidationisinverselyproportionaltoenergylevel,thecomplexesarearrangedinadecreasingorderofenergylevel.So,whenelectronsmovefromonecomplextoanother,itmeanselectronsmovefromacomplexofhighenergytoacomplexoflowenergyandthatliberatesenergy.Thisenergyisusedforpumpinghydrogenionsfromthemitochondrialmatrixtojustoutsidetheinnermitochondrialmembrane.Afterhydrogenionsaccumulateoutside
theinnermitochondrialmembrane,hydrogenionsgothroughFOComponentofATPsynthase.
329.Electrontransportchainallaretrue except a)Complexesarearrangedinanincreasingorderofredox potential; b)MitochondrialGlycerolphosphatedehydrogenasesendsits electrondirectlytoQ c)l0HydrogenionsaretranslocatedwhenNADHentersinto anelectrontransportchain d)7HydrogenionsaretranslocatedwhenFADH2electrons getintoelectrontransportchain. CorrectAnswer-DAns.is'd'i.e.,7HydrogenionsaretranslocatedwhenFADH2electronsgetintoelectrontransportchainNADHelectronsgetintoelectrontransportchainthroughcomplexI.EnergydifferencebetweenNADHandQisinsuchawaythatwhenelectronsmovefromcomplexItoQ,4hydrogenionsgettranslocated.Similarly4ionsgettranslocatedwhenelectronsmovefromQtocomplexIIIand21-1'ionsgettranslocatedwhenelectronsmovefromcomplexIIItoIV.Sototally101-1+ionsgettranslocatedwhenelectronsfromNADHgetintoelectrontransportchain.ComplexVorATPsynthasecomplexworksinsuchawaythatwhen10H*ionsgothroughF0component,1ATPisgenerated.Sowhen10Hydrogenionsaretranslocated,2.5ATPscanbegenerated.FADH,electronsgetintoelectrontransportchainthrougheithercomplexIIortheydirectlygetintoQ,ineithercase,noenergyisliberated.Nohydrogenionsaretranslocated.Whenelectronsmove
fromQtoComplexIII,4hydrogenionsandwhenelectronsmovefromIIItoIV2hydrogenionsaretranslocated.Sototally6hydrogenionsaretranslocatedwhenFADH2getsintoelectrontransportchain.ATPsynthasecomplexgenerates1ATPforevery4hydrogenionstranslocatedthroughF,component.Sofor6hydrogenions,itis1.5ATP
330.Whichofthefollowingisthe respiratorycentreofcell? a)Mitochondria b)Microsome c)Lysosome d)Nucleus CorrectAnswer-AAns.is'a'i.e.,MitochondriaAsmitochondriaharbourstheelectrontransportchain.Inelectrontransportchain,theelectronsfromNADHandFADH2aretransferredthroughthevariouscomplexestofinallyOxygen.Oxygenisthenconvertedtowater.ThiswayallfuelsgetoxidisedtoCarbondioxide.Inotherwordsinmiotochondria,OxygenisutilisedandCarbondioxidegenerationissupported.Henceitiscalledastherespiratorycentreofthecell.
331.Celluloseisbiochemically- a)(1,4)Lglucose b)?,(14)Dglucose c)(1,4)Dglucose d)?(1,4)Lglucose CorrectAnswer-AAns.is'a'i.e.,(1,4)LglucoseCelluloseisacomponentofcellwall.Celluloseisastructuralhomopolysaccharidemadeupofglucosemoleculeslinkedby13(1,4)linkages.Humanscannotdigestcellulosebecausehumandigestiveenzymescannotbreak43(1,4)linkagespresentinoligosaccharidesandpolysaccharides.Thisiswhyvegetariandietisconsideredtoprovidefibretothediet.
332.DandLisomerismis- a)Opticalisomerism b)Functionalisomerism c)Epimerism d)Enantiomerism CorrectAnswer-DAns.isd.i.e.,EnantiomerismEnantiomerismisatypeofstereoisomerisminwhichtwomoleculeshavethesamemolecularformulaandthesamestructuralformulabuttheydifferinspatialorientationwithrespecttoallthecarbonatomsandtheyarenamedbasedontheorientationinthepenultimatecarbonatom.Inthepenultimatecarbonatom,ifOHisontherightside,itisDform,ifOHisontheleftside,itisLform.TheothernameforenantiomerismisRacemism.
333.Allofthefollowingareconvertedto cr-ketoglutarateoncatabolismexcept- a)Glutamate b)Histidine c)Proline d)Glycine CorrectAnswer-DAns.is'd'i.e.,Glycine[RefHarper30th/ep.162,250/ep.166,167]
334.Glucogenicaminoacidsgiverisetoall ofthefollowingintermediatesofcitricacidcycleexcept- a)Isocitrate b)cketoglutarate c)SuccinylCoA d)Fumarates CorrectAnswer-AAns.is'a'i.e.,Isocitrate
335.Whatistheprecursorofprolinein Krebscycle? a)Oxaloacetate b)cketoglutarate c)SuccinylCoA d)Fumarates CorrectAnswer-BAns.is'b'i.e.,cketoglutarate[RefEssentialsofBiochemistryp.232;Harper29`'/ep.ProlineisanalphaaminoacidwithapyrrolidineringItisanonpolariminoacidwithNHasoneofitsfunctionalgroupsItdisruptsahelixItisanonessentialaminoacidandissynthesizedfromanon-essentialaminoacidglutamateGlutamateinthepresenceofyglutamatekinasegetsconvertedtoglutamate5phosphate,whichinthepresenceofyglutamatedehydrogenasegetsconvertedtoyglutamatesemialdehyde.yglutamatesemialdehydespontaneouslycyclisestoformypyrrolinecarboxylatewhichinthepresenceofreductaseformsproline
336.usedincitricacidcycleareallexcept- a)NAD b)FAD c)NADP d)GDP CorrectAnswer-CAns.C.NADP Enzyme Reducingequivalent ATP Isocitratedehydrogenase 1NADH 2.5 alphaketoglutaratedehydrogenase 1NADH 2.5 SuccinylCoA ATP/GTP 1 Succinatedehydrogenase FADH2 1.5 Malatedehydrogenase NADH 2.5 total 10
337.Allofthefollowingstepsactas sourcesofenergyincitricacidcycleexcept- a)Citratesynthase b)Isocitratedehydrogenase c)SuccinylThiokinase d)SuccinateDehydrogenase CorrectAnswer-AAns.is'a'i.e.,Citratesynthase
338.Trueaboutglucokinaseis- a)Itispresentinallcells b)Itisaconstitutiveenzyme c)Ithasahighkm d)Itisinhibitedbyglucose6phosphate CorrectAnswer-CAns.is'c'i.e.,Ithasahighkm S. Property Hexokinase Glucokinase No. Liverand 1 Location Allcells Pancreatic(3cells 2 Affinity High Low 3 Km Low High Inhibitionbyglucose6 4 Yes No phosphate No(Constitutive Yes(Inducible 5 InductionbyInsulin enzyme) Enzyme)
339.Allofthefollowingaretrueabout lactateutilisationinliverexcept- a)TotalnetnumberofATPformedbecauseofcori'scycleis 6 b)Cori'scycleshiftsthemetabolicburdenfrommuscletoliver c)Cori'scyclecannotbesustainedindefinitelybecauseitis energeticallyunfavourable d)Cori'scycleislinkedtoglycogensynthesisinmuscle CorrectAnswer-AAns.is'a'i.e.,TotalnetnumberofATPformedbecauseofcoil'scycleis6CORI'SCYCLEMuscleusesamoleculeofglucosethroughanaerobicglycolysisandgets2ATPs.Inthisprocess,glucosebecomestwomoleculesoflactate.The2lactatemoleculesthroughcirculationreachliver.Inliver,thetwomoleculesoflactateareutilisedthroughgluconeogenesistoformaglucosemoleculeattheexpenseof6ATPs.Theglucoseformedinliverreachesmuscleandisutilisedforagainanaerobicglycolysisifthemuscleisstillexercising.Incasemuscleisdonewithexercising,theglucosewhichreachesthemusclefromliverisusedforglycogensynthesis.
340.Whichofthefollowingistrueabout effectofinsulinandglucagonongluconeogenesis? a)Insulinfavourstheformationoffructose2,6bisphosphate b)Fructose2,6bisphosphateisaninhibitorofglycolysis c)Insulinactsthroughakinase d)GlucagonstimulatesPFK.2activityofthetandemenzyme CorrectAnswer-AAns.is'a'i.e.,Insulinfavourstheformationoffructose2,6bisphosphateGlycolysisandgluconeogenesisarereversalofeachother.Hencethetwopathwaysshouldberegulatedinsuchawaythatwhenonepathwayisactive,theotheronehastobeinactive.Otherwisetheywillendupinfutilecycles.
341.Inglycogensynthesistheactiveform ofglucoseusedis- a)Glucose6phosphate b)GlucoseIphosphate c)UDPglucose d)UTPglucose CorrectAnswer-CAns.is'c'i.e.,UDPglucoseGlycogensynthesisoccursinliverandSkeletalMuscleUDPglucoseistheactiveformofglucosewhichgetsaddedtothegrowingglycogenThenumberofhighenergyphosphatesrequiredforattachingaglucosemoleculetogrowingglycogenis3TheratelimitingenzymeofglycogensynthesisisglycogensynthaseGlycogensynthasegetsactivatedbydephosphorylationGlycogensynthaseattachesglucoseresiduesonebyonealongastraightchain,linkedbya(1,4)linkages.Thiscontinuesuntil11to13residuesareattachedinastraightchain.Atbranchpointsinglycogen,a(1,6)linkagesshouldbeformed.
342.Neonatalhypoglycaemiawhichdoes notrespondtocounterregulatoryhormoneadministrationisdiagnosticof- a)Her'sdisease b)Cori'sdisease c)Anderson'sdisease d)VonGierke'sdisease CorrectAnswer-DAns.is'd'i.e.,VonGierke'sdiseaseGlycogenstoragedisorderspresentingwithhypoglycaemiaareTypeI(VonGierke'sdisease),TypeIII(Cori'sdiseaseorForbe'sdisease),TypeVI(Her'sdisease),TypeIX(FanconiBickelsyndrome)TheonlyGlycogenstoragedisorderwhichpresentsashypoglycaemianotrespondingtocounterregulatoryhormoneadministrationisVonGierke'sdiseaseMuscleinvolvementisnotafeatureofTypeI(VonGierke'sdisease),TypeIV(Andersoendisease),TypeVI(Her'sdisease),TypeIX(FanconiBickelsyndrome)AndersendiseaseorTypeIVistheonlyglycogenstoragediseasewhichpresentswithneitherhypoglycaemianorwithmuscleinvolvement.Itpresentsashepatomegalyandcirrhosis
343.Whichofthefollowingisatransfatty acid? a)Oleicacid b)Elaidicacid c)Stearicacid d)Arachidonicacid CorrectAnswer-BAns.is'b'i.e.,Elaidicacid[RefHarper30"/ep.213]Therearetwotypesoffattyacids:SaturatedUnsaturatedCis-transisomerismisforunsaturatedfattyacids.Stearicacidisasaturatedfattyacid(Nocis-transisomerism)Onlyimportantunsaturatedtrans-fattyacidisElaidicacid(trans-9-octadecenoic)
344.ActivatorsofAcetylCoAcarboxylase areallexcept a)AcylcoA b)Citrate c)Glutamate d)Dicarboxylicacid CorrectAnswer-AAns.is'a'i.e.,AcylCoA[RefHarper29thlep.217,220]AllostericmodulationofacetylCoAcarboxylase 1. Activaters:Citrate(tricarboxylicacid);glutamate(dicarboxylicamino acid)&otherdicarboxylicacids;ATP 2. Inhibitors:AcylCoA
345.Arachidonicacidoxidationinvolves howmanycyclesofbetaoxidation? a)l0 b)20 c)9 d)8 CorrectAnswer-CAns.is'c'i.e.,9NumberofacetylCoAformedin(3-oxidationoffattyacids=Numberofcarbonatoms/2.Numberofcyclesof(beta-oxidationrequired-Noofcarbon/2(-1)Hencearachidonicacidwith20carbonatomsundergoespoxidationtoform10acetylCoAbygoingthrough(20/2)-1cyclesi.e.,9cycles.
346.Allaretrueaboutbetaoxidationof fattyacidsexcept- a)CarnitineacyltransferaseIistheratelimitingenzymeof fattyacidoxidation b)CarnitineacyltransferaseIisstimulatedbyAcylCoA c)CarnitineAcyltransferaseIisstimulatedbymalonylCoA d)CarnitineAcyltransferaseIdefectcausesadecreasein acylcarnitinelevels CorrectAnswer-CAns.is'c'i.e.,CarnitineAcyltransferaseIisstimulatedbymalonylCoAAsCATIistheratelimitingenzymeoffattyacidoxidation,itssubstrateisacylCoA.Asweknowthatallenzymesgetstimulatedbytheirsubstrates,acylCoAstimulatesCATI.MalonylCoAisaproductofacetylCoAcarboxylase(ACC).ACCistheratelimitingenzymeoffattyacidsynthesis,ananabolicpathway.So,malonylCoAisanintermediateofanabolicpathway.Henceitisasignalofhighenergy(Anabolismhappensonlyinhighenergystatus).Whentheenergyisalreadyhigh,wedonotwantfattyacidstobefurtheroxidised.Wewantfattyacidstobeonlystored.So,malonylCoA,asignalofhighenergyinhibitsCATI.Inshort,anythingwhichsignalslowenergystimulatesfattyacidoxidation(CATI).So,ADP,NAD,FAD,Glucagon,AcylCoAstimulatefattyacidoxidationAnythingwhichsignalhighenergyinhibitfattyacidoxidation.So,ATP,NADH,FADH2,InsulinandmalonylCoAinhibitfattyacidoxidation.Fattyacidoxidationdefectspresentasnonketotichypoglycaemia,
hyperammonemia,dicarboxylicaciduria.Andallfattyacidoxidationdefectsalsopresentwithincreaseinacylcarnitinelevels.OneexceptionisCATIdefect.InCATIdefect,asacylCoAisnotconvertedtoacylCarnitine,freecarnitinelevelsarehighandacylcarnitinelevelsarelow.
347.AIIaretrueaboutbetaoxidationoffats acidsexcept- a)Occursinmitochondria b)Occursinperoxisome c)Resultsinhydrogenperoxidegeneration d)Fattyacidoxidationdefectspresentwithketosis CorrectAnswer-DAns.is'd'i.e.,FattyacidoxidationdefectspresentwithketosisFattyacidoxidationdefectcausesnon-ketotichypoglycemia.Fattyacidoxidationhappensinmitochondriaandinperoxisomes.Thedifferencebetweenmitochondrialoxidationandperoxisomaloxidationisthatinmitochondria,whenthe13carbonatomisoxidised,thehydrogenatomsareremoved.ThosehydrogenatomsareusedforreducingNADandFADtoformNADHandFADH2.NADHandFADH2enterintoelectrontransportchaintoformATP.Inperoxisome,thehydrogenatomremovedfrom(3carbonatomisusedtoreduce02formingF1202.Onlybecause11202isformedinperoxisomeby(betaoxidationtheorganismiscalledso)
348.Whichofthefollowingistrueabout Betaoxidationoffattyacids? a)Stearicacidonoxidationprovides106ATPs b)OddchainfattyacidoxidationprovidesonlypropionylcoA c)Fattyacidoxidationdefectscausehypoglycemia d)Ketonebodiesareformedbyincompleteoxidationoffatty acidduringstarvationtoincreaseenergyproduction CorrectAnswer-CAns.is'c'i.e.,FattyacidoxidationdefectscausehypoglycaemiaDefectinfattyacidoxidationcauseshypoglycemia.AboutotheroptionsStearicacidoxidationproduces122ATPs.Evenchainfattyacidsare(3-oxidizedtoacetylCoA.Oddchainfattyacidsarealso(3-oxidizednormallybutthelaststepproducesa3-carbonpropionylCoAalongwithanacetylCoA(insteadof2moleculesacetylCoAthatoccursinevenchainfattyacids).Ketonebodyformation(ketogenesis)occurswhenthereisahighrateoffattyacidoxidationinliverwhichprovidesexcessiveacetylCoA,substrateforketogenesis.Whenketonebodiesareformed,aswecan'texpectthe10ATPswhichwegetfromeveryacetylCoAthroughcitricacidcycle,theformulaforenergeticsofincompleteoxidationoffattyacidsis:
349.Whichofthefollowingistrueabout propertiesofVLDL/LDL- a)Inelectrophoresis,VLDLmigratesmorecathodalthanLDL b)LDLisformedfromliver c)LDLisformedfromChylomicron d)VLDLremnantsreachextrahepatictissues CorrectAnswer-BAns.is'b'i.e.,LDLisformedfromliverLipoproteinelectrophoresisofafastingsampleshowsthreebands-HDL,VLDL,LDLinthatorderfromanodetocathode.VLDLissynthesizedinliverthatcontainshightriglyceride,ChE,cholesterol,phospholipidandApoB-100.(VLDLparticlesresemblechylomicronesincompositionexceptthatVLDLcontainsApoB-100insteadofApoB-48).VLDLparticlesaresecretedintheplasmaandaswithchylomicron,ApoEandApoCaretransferredfromHDLtoVLDL.NowVLDLcontainsApoB-100,ApoEandApoC.Inplasma,triglyceridesofVLDLarehydrolysedbysamelipoproteinlipase(seeabove)andapoCistransferredtoHDLandtheremmantsarecalledIDL.40-60%ofIDLisremovedbyliverviaLDLreceptormediatedendocytosis,thisprocessrequireApoEwhichactsasligandforLDLreceptors.RemainingIDLisremodeledbyhepatic(liver)lipasewhichhydrolyzesmoretriglyceridetoformLDLthatcontainsmaximumcholesterol.70%ofLDLisremovedbyliverviaLDLreceptorand30%isutilizedbyperipheraltissuesasasourceofcholesterol.
350.Reversecholesteroltransport-allare trueexcept- a)Transportofcholesterolfromextrahepatictissuestoliver b)ATPBindingCassetteTransporterproteinisinvolvedinthe conversionofHDL3toHDL2 c)LecithinCholesterolAcylTransferasehelpsinthe conversionofSpheroidalHDLtoDiscoidalHDL d)CholesterolEsterTransferProteinhelpsinincreasingHDL level CorrectAnswer-DAns.is'd'i.e.,CholesterolEsterTransferProteinhelpsinincreasingHDLlevelReverseCholesterolTransportisthetransportofCholesterolesterandphospholipidfromextrahepatictissuestoliver.HDLisreleasedbybothliverandintestinalcells.Inboththecases,theyarereleasedasdiscoidalHDLApoAlactivatesLecithinCholesterolAcylTransferaseanditconvertsdiscoidalHDLtoSpheroidalHDL(HDL3)HDL3activatesABC1(ATPBindingCasetteTransporter1)tocollectcholesterolandphospholipidsfromextrahepatictissuemembranes.ThiswayHDL3sizeincreasesanddensitydecreases.HenceitformsHDL2.ThisHDL2reacheslivertoemptyitscontentsintoliver.Onthewaytoliver,ifHDL2encountersIDL,CholesterolEsterTransferProtein(CETP)transfersChoelsterolesterfromHDL2toIDL,convertingIDLtoLDL.HenceCETPdecreasesHDLlevelandincreasesLDLlevel.
351.TrueaboutcoproporphyrinIand coproporphyrinIIIis- a)CoproporphyrinIisexcretedinurine b)CoproporphyrinIIIisexcretedinbile c)InDubinJohnsonSyndrome,CoproporphyrinIinurineis80% ofthetotalcoproporphyrin d)InDubinJohnsonSyndrome,totalcoproporphyrinlevelsis elevated CorrectAnswer-CAns.is'c'i.e.,InDubinJohnsonSyndrome,CoproporphyrinIinurineis80%ofthetotalcoproporphyrinCoproporphyrinsareintermediatesofhemesynthesisNormallycoproporphyrinIisexcretedinbileandislostinfecesCoproporphyrinIIIisexcretedinurineHenceinnormalurineCoproporphyrinIis25%oftotalcoproporphyrinlevelsinurineDubinJohsonsyndrome,isaformofconjugatedhyperbilirubinemiaandiscausedbyadefectofMultiDrugResistantProtein2(MRP-2),whichisresponsibleforsecretingbilecomponents(conjugatedbilepigments)fromhepatocytesintobiliarycanaliculi.Inthisdisorder,theratioofCoproporphyrinI:CoproporphyrinIIIisreversedandcoproporhyrinIismorethan80%ofthetotalCoproporphyrinlevels.Butthetotalcoproporphyrinlevelsisnormal.PossiblemechanismisCoproporphyrinIissecretedintobilethroughMRP-2.
352.Syntheticoxygencarrieris? a)2,4dinitrophenol b)Chloflurocarbon c)Perflurocarbon d)1fluro2,4dinitrophenol CorrectAnswer-BAns.is'b'i.e.,ChloflurocarbonBlooddopingisaformoffraudulentincreaseintheoxygencarryingcapacityofaperson,widelyusedtoimprovetheaerobiccapacityofathletesThisisdonebyvariousmethodsAutologousbloodtransfusionHomologousbloodtransfusionErythropoietinorContinuousErythropoietinReceptorActivator
353.Abetalipoproteinemiaaffects? a)Retinalpigmentepithelium b)Opticnerve c)Occipitalcortex d)Bipolarneurons CorrectAnswer-AAns.is'a'i.e.,RetinalpigmentepitheliumAbetalipoproteinemiaorBassen-KornzweigsyndromeiscausedbyadefectofMicrosomalTriglycerideTransferProtein(MTTP).Inabetalipoproteinemia,bothchylomicronandVLDLformationgetaffected.Asaresult,fatabsorptionisaffectedandtheaffectedchildpresentswithsteatorrheainthefirstfewmonthsoflife.Allfatsolublevitaminabsorptionalsogetaffected.HenceVitaminA,D,EandKdeficiencyisexpected,howeverVitaminEdeficiencyisfoundtohaveprofoundeffects.VitaminEdeficiencypresentsasretinitispigmentosaandsubacutecombineddegeneration.Otherfeaturesofabetalipoproteinemiaareacanthocytes(starshapedRBCsinperipheralsmearcausedbecausethelipidcompositionofRBCmembranegetsaffected),hypocholesterolemia.TreatmentinvolvesvitaminEadministration.
354.GeneticallymediatedVLDL overproductionisafeatureofallexcept? a)Familialcombinedhyperlipidemia b)Hypoapobetalipoproteinemia c)Familialdyslipidemichypertension d)LDLsubclassB CorrectAnswer-BAns.is'b'i.e.,Hypoapobetalipoproteinemia[RefEssentialsofBiochemistryp.712]FamilialcombinedhyperlipidemiaorTypelibFamilialhyperlipoproteinemiaischaracterisedbygeneticallydeterminedoverproductionoftriglyceriderichVLDL(VLDL1)andsmalldenseLDLparticles.Itisthemostcommonlyinheriteddisorder.PleaserememberAcquiredcombinedhyperlipidemiawithsamefeaturesiscausedbymetabolicsyndromeorinsulinresistance.Hyperapobetalipoproteinemiaischaracterizedbyanincreasednumberofsmall,denseLDLparticlesandanelevatedLDL-BlevelwithnormalorborderlinehighLDL-Clevels.PatientswithHyperapobetalipoproteinemiamayhavenormalorhightriglycerides.Hyperapobetalipoproteinemiahasbeenfoundtobethemostcommonphenotype(34%)associatedwithprematureCAD;HyperapobetalipoproteinemiawithhypertriglyceridemiaisfoundtobeevenmorestronglyassociatedwithCADthanHyperapobetalipoproteinemiawithnormaltriglycerides.
355.Gerhardt'stestisusedtodetect? a)Reducingsugar b)Ketonebody c)Protein d)Blood CorrectAnswer-BAns.is'b'i.e.,KetonebodyGerhardt'stestisatestusedtodetectacetoacetateinurine(acetoneand(3hydroxybutyratedonotanswerthistest).ReagentsusedforGerhardt'stestincludeConcentratednitricacidand10%Ferricchloride
356.Foldsincollagenaredueto- a)Glycine b)Proline c)Hydroxyproline d)Lysine CorrectAnswer-A:BAns.is`b>a'i.e.,Proline>Glycine[RefEssentialsofbiochemistyp.868]Twoaminoacidsareinvolvedinproducingfoldsincollagen:prolineandglycine.Inordertoformatriple-helixapolypeptidechain(a-chain)mustcontainglycineaseverythirdresidueinthesequence.Thisisbecauseonlytheglycineissmallenoughtobeaccommodatedinthelimitedspaceavailabledownthecentralcoreofthetriplehelix.Eachturnofpolypeptidechain(a-chain)containsthreeaminoacidresidues,andglycine(Gly)ispresentateverythirdposition.Thusglycineconstitutes33%ofthetotalaminoacidresidues.Therepeatingaminoacidresidues,representedas(Gly-X-Y)n,isanabsoluterequirementforformationoftriplehelix.XandYcanbeanyaminoacids,butmostofthetimeXisproline(10%ofthetotalaminoacidresidues)andmostofthetimeYishydroxyproline.Otherimportantaminoacidsfoundincollagenarelysineandhydroxylysine.
357.Progesteronesynthesisrequires- a)LDL b)VLDL c)HDL d)Chylomicron CorrectAnswer-CAns.is'c'i.e.,HDLGranulosacellsusefollicularfluidHDLasasourceofcholesterolforthesynthesisofprogesterone.UndertheinfluenceofLH,corpuslutealcellstakeupcholesterolfromfollicularfluidHDLandconvertcholesterolintoprogesterone.
358.Themostabundantaminoacidof collagenis- a)Glycine b)Proline c)Lysine d)Tryptophan CorrectAnswer-AAns.is'a'i.e.,Glycine
359.Siteofsmallchainfattyacid absorptionis- a)Ileum b)Duodenum c)Ascendingcolon d)Rectum CorrectAnswer-CAns.is'c'i.e.,AscendingcolonShortchainfattyacids(SCFA)arefattyacidswith2to6carbonatoms.Theyarethemajorend-productsofthemicrobialdigestionofcarbohydratesinthealimentarycanal.Theseshortchainfattyacids,butyrateparticularlyisimportantforcolonhealthbecauseitistheprimaryenergysourceforcoloniccellsandhasanti-carcinogenicaswellasanti-inflammatorypropertiesthatareimportantforkeepingcoloncellshealthy.Butyrateinhibitsthegrowthandproliferationoftumorcelllinesinvitro,inducesdifferentiationoftumorcells,producingaphenotypesimilartothatofthenormalmaturecell,andinducesapoptosisorprogrammedcelldeathofhumancolorectalcancercellsThehighestconcentrationsareobservedinthelargeintestine(caecumandcolon)ofallthemammals.Humancaecumandproximalcolonhavehighluminalconcentrationsoforganicnutrients(non-starchpolysaccharidesfromplantcellwalls,andproteinsnotabsorbedbythesmallintestine)whichmaintainhighbacterialgrowthrates.Againstthisfermentativebackground,antiperistalsisensuresretentionandthoroughmixingoffaecesintheproximalcolon,whichisthesiteofmaximalSCFAproduction.SCFAabsorptionisconcentrationdependentandoccurs
mostreadilyintheproximalcolon(Includescecum,ascendingcolonandtransversecolon).
360.Allofthefollowingaretrueabout collagenstructureexcept- a)Collagenissecretedbyfibroblastsasprocollagen b)LysyloxidaseisdependentonVitaminC c)Hydroxylysineundergoesglycosylation d)Glycineisthemostabundantaminoacidofcollagen CorrectAnswer-BAns.is'b'i.e.,LysyloxidaseisdependentonVitaminCCollagenisthemostabundantproteininthebody.Collagenisatriplehelix.Itismadeupof3polypeptidechains-Eachpolypeptidechainhasabout1000aminoacids.Itismadeupofrepetitiveunitsof(Gly-X-Y),whereXandYaremostcommonlyprolineandhydroxyproline.Hence33%ofaminoacidresiduesofcollagenisglycine-themostabundantaminoacidofcollagen.Collagenissynthesisedasprocollagenbyfibroblastsintracellularly.AftertranslationofmRNAofcollageninribosomes,thepolypeptidechainsundergoposttranslationalmodificationsintheformofhydroxylationandglycosylation.
361.HMGCoAisprecursorofallexcept- a)Ubiquinone b)Dolichol c)Bilepigments d)Ketonebody CorrectAnswer-CAns.is'c'i.e.,Bilepigments3-Hydroxy3methylglutarylCoAorHMGCoAisformedfromacetylCoA.
362.SmallRNAsare? a)Between200and500bpsinlength b)Codedbysmallexons c)Amodeofregulationofgeneexpression d)Alwaysendogenouslysynthesised CorrectAnswer-CAns.is'c'i.e.,AmodeofregulationofgeneexpressionSmallRNAsarelessthan200nucleotidesinlength.Theyarecodedbyintronicsequencesofgenes.TheyhelpinregulationofgeneexpressionthroughGENESILENCINGmechanismThemiRNAgenesequenceslocatedwithinintronicsequencesaretranscribedbyRNApolymeraseIIItoformPri-miRNA.Pri-miRNAisprocessedbymicroprocessorcomplextoformastemloopstructure,Pre-miRNA.
363.Whatistheparameterthatisusedto assesslipidperoxidation? a)Malondialdehyde b)CRP c)hsCRP d)Carboxymethyllysine CorrectAnswer-AAns.is'a'i.e.,MalondialdehydeROScanbeproducedbyeitherbreakageofcovalentbond,additionofelectronstoamoleculeorremovalofhydrogenbyotherradicals.Theyaregenerallyhighlyreactivespeciesandtypicallyactaselectrophilicspeciesoroxidantagents.Themostimportantradicalsorpro-oxidantmoleculesinvolvedindiseaseprocessesaresuperoxide(02-),hydroxylradical(OH),hydrogenperoxide(H202)andcertainoxidesofnitrogen,likenitricoxide(NO)andperoxynitrite(ONOO-)2Sinceitiscomplexmeasuringfreeradicalsdirectlyinvivo,itisnecessarytocarryoutthequantificationofcellularcomponentswhichcanreactwiththesefreeradicals,suchasproteins,DNAandmainlylipids.Oncelipidperoxidesareunstablecompounds,theytendtodegraderapidlyinavarietyofsubproducts.MDA(Malondialdehyde)isoneofthemostknownsecondaryproductsoflipidperoxidation,anditcanbeusedasamarkerofcellmembraneinjury.MDAisathree-carbon,low-molecularweightaldehydeformedbycyclizationofaldehydeswhichhaveunsaturationinaor13positionsSeveralmethodshavebeendevelopedtoassessMDA,including
quantitativemethodsusingspectrophotometryorfluorimetricdetection,highperformanceliquidchromatography(HPLC),gaschromatographyandimmunologicaltechniquesOthermarkersofoxidativestressincludeconjugateddienes,ethaneandpentanegases,isoprostanesand4-HNE(4-hydroxy2-nonenal)
364.UbiquitinProteasomepathwayisused fordegradationof? a)Extracellularlonglivedproteins b)Intracellularlonglivedproteins c)Intracellularshortlivedproteins d)Extracellularshortlivedproteins CorrectAnswer-CAns.is'c'i.e.,IntracellularshortlivedproteinsExtracellularproteinsandintracellularlonglivedproteinsgetdegradedinlysosomeswiththehelpofcathepsinIntracellularshortlivedproteinsgetlabelledwithubiquitinoncetheirlifespangetsover.
365.Aminoacidinsynthesisof neurotransmitter a)Glutamate b)Proline c)Cysteine d)Alanine CorrectAnswer-AAns.is'a'i.e.,Glutamate Aminoacid Neurotransmitter Glutamate Glutamate&GABA Glycine Glycine Phenylalanine&Tyrosine Dopamine,Norepinephrine&EpinephrineTryptophan Serotonin
366.Maximumbufferingcapacityofabuffer ismaximumatpH a)Lessthanpka b)Morethanpka c)Equaltopka d)Hasnorelationwithpka CorrectAnswer-CAns.is'c'i.e.,Equaltopka[RefHarper30th/ep.21&29'11ep.20,21,18;Vasudevan6thiep.22,23]MaximalbufferingcapacityoccursatpHequaltopkaofbuffer.Therefore,toworkasabestbufferatphysiologicalpHaminoacidshouldhavepkavalueclosetophysiologicalpH(7.4).Aminoacidscanhavebufferingactionduetothreeionizablegroups:-a-carboxylgroup:-Differentaminoacidshavepkavalueofa-carboxylgroupbetween3.5-4.So,carboxylgroupofaminoacidshasmaximumbufferingcapacitybetweenpH3.5-4.a-aminogroup:-Differentaminoacidshavepkavalueofa-aminogroupbetween8.0-9.0.Thus,a-aminogrouphasmaximumbufferingcapacitybetweenpH8.0-9.0.Specialionizablegroup(insomeaminoacids):-Amongspecialionizablegroupofaminoacids,imidazolegroupofhistidinehaspkavalue6.5-7.4,whichisclosesttophysiologicalpH.Hence,histidine(duetoimidazolegroup)hasmaximumbufferingcapacityatphysiologialpH.
367.LacYinLacOperoncodesfor? a)BGalactosidase b)GalactosidePermease c)ThiogalactosideTransacetylase d)Repressor CorrectAnswer-BAns.is'b'i.e.,GalactosidePermeaseThesecodefor3proteinsthatareinvolvedincatabolismoflactose.Thesegenesare'Z'gene(codesforP-galactosidase),'Y'gene(codesforgalactosidepermease),and'A'gene(codesforthiogalactosidetransacetylase).
368.Essentialamino-aciddeficiencyaffect nitrogenbalanceby a)Increasingproteindegradation b)Decreasingproteindegradation c)Decreasingproteinsynthesis d)Increasingproteinsynthesis CorrectAnswer-CAns.is'c'i.e.,Decreasingproteinsynthesis[RefPrinciplesofmedicalBiochemistryp.464]Nitrogenbalanceisthedifferencebetweeningestednitrogenandexcretednitrogen.Nitrogenbalance=Ningested-NexcretedBecausedietaryproteinsareanimportantsourceofnitrogen,nitrogenbalanceisanimportantindexofproteinandaminoacidmetabolism.Inhealthyadults,nitrogenbalanceiszero,i.e.astateofnitrogenequlibriumexists,wherenitrogenintakeisequaltonitrogenexcretion.Negativenitrogenbalance(excretionexceedsintake)indietaryproteindeficiencyInadult,evenofproteinstarved,atleast30-40gmofaminoacidsaredegradedeachday;thisamountdefinestheminimumdietaryrequirment.Ifdietarysupplydropsbelowthislimit,anegativenitrogenbalanceoccursandthebodyproteinislost.Essentialaminoaciddeficiencyhasthesameeffectbecauserelativedeficiency.
369.Functionoftyrosinaseis a)Synthesisofnorepinephrine b)Synthesisofdopamine c)Synthesisofmelanin d)Alloftheabove CorrectAnswer-CAns.is'c'i.e.,Synthesisofmelanin[RefHarper29th/ep.288-290]Note-TyrosinehydroxylaseandtyrosinasecatalyzestheconversionoftyrosinetoDopa,butbotharedefferentenzymes.Tyrosinehydroxylaseisinvolvedincatecholaminessynthesisinadrenalmedullaandsympatheticganglia,whereastyrosinaseisinvolvedinmelaninsynthesisinmelanoblastsofskin.
370.ChimericDNAtrueareallexcept? a)FormedbylinkingDNAfragmentsofunrelatedgenome b)Stickyendproducingrestrictionendonucleasesfavour formationofchimericDNA c)Theydon'trequireDNAligases d)TheorganismharbouringachimericDNAhasfeaturesof themselvesandthepropertiesoftheinsert CorrectAnswer-CAns.is'c'i.e.,Theydon'trequireDNAligasesChimericDNAorrecombinantDNAisformedbylinkingDNAfragmentsoftwounrelatedgenome.ItisastepinvolvedinrecombinantDNAtechnology.ItisdonetointroduceafavourablequalityintoanorganismlikeabilitytoproduceinsulinbyE.Coli(DonebylinkinginsulincDNAintoavectorandintroducingtherecombinantvectororchimericDNAintoE.Coli)orinsectresistanceincrops(donemyintroducingthegenefragmentcapableofproducingBacillusthurengiensis)intoTiplasmidandintroducingthechimericDNAorrecombinantDNAintogrowingplants).
371.Enzymewhichactsonaspartate a)SerumGlutamatePyruvateTransaminase(SGPT) b)SerumGlutamateOxaloacetateTransaminase(SGOT) c)Ornithinetranscarbmaylase(OTC) d)Argininosuccinatelyase(ASL) CorrectAnswer-BAns.is'b'i.e.,SerumGlutamateOxaloacetateTransaminase(SGOT)SGPTcatalaysesthetransaminationbetweenAlanineandaKetoglutarate.Alanine+aKetoglutaratePyruvate+GlutamateItisinnowayrelatedtoaspartate.SGOTcatalysesthetransaminationbetweenAspartateandaKetoglutarate
372.Proteinsarestoredas? a)Structuralproteins b)Functionalproteins c)Fats d)Lysosomalenzymes CorrectAnswer-CAns.is'c'i.e.,FatsThereisnostorageformofproteinHencetheaminoacidsformedbybreakdownofproteinsundergocatabolismDuringcatabolism,mostoftheaminoacidsgiveofftheiraminogroupsandthenthecarbonskeletonundergoescatabolismOncatabolism,thecarbonskeletonofaminoacidsgiverisetoglycolyticintermediateorcitricacidcycleintermediates.
373.Allostericstimulatorofglutamate dehydrogenaseis a)ATP b)GTP c)PalmitoylCoA d)Leucine CorrectAnswer-DAns.is'd'i.e.,LeucineGLDHisallostericallystimulatedbyADP,GDP,leucine,valineandisoleucine.ItisinhibitedbyATP,GTP,palmitoylCoAandZinc.
374.AminoacyltRNAgetsattachedtowhich siteofribosome? a)Psiteof40sribosome b)Asiteof60sribosome c)Asiteof40sribosome d)Psiteof60sribosome CorrectAnswer-BAns.is'b'i.e.,Asiteof60sribosomeTranslationisaprocessbywhichnucleotidebasesofmRNAgettranslatedasaminoacidsequencesofpolypeptidechain.Ittakespartinfreeribosome.FreeribosomereadsthemRNAfrom5'endto3'end.ItreadsthecodonsofmRNAonebyone.DependinguponthecodonthatispresentinmRNA,ribosomeiscapableofattachingacomplementaryanticodoncontainingtRNA.ThistRNAcarriesacorrespondingaminoacid.Thiswaythepolypeptidechaingrowsfromaminoterminalendtocarboxyterminalend.Eukaryoticribosomeisa80sunit.Itdissociatesinto40sand60ssubunits.60ssubunitcontainsPsiteandAsite.Whenribosomeentersintochainelongation,onthePsiteof60s,isattachedtheAUGcodonofmRNA,towhichinitiationmethioninetRNAisattachedandAsiteisfree
375.Whichofthefollowingisabiologically importanttripeptide? a)Thyrotropinreleasinghormone b)Thyroidstimulatinghormone c)Gonadotropinreleasinghormone d)FollicleStimulatinghormone CorrectAnswer-AAns.is'a'i.e.,ThyrotropinreleasinghormoneTripeptideisapeptidewith3aminoacidsand2peptidelinkages.Biologicallyimportanttripeptidesincludeglutathione,TRH(ThyrotropinReleasingHormone)andmelanostatin.TSHisaglycoproteinnotapeptide.Itismadeupoftwosubunits-aand(Iasubunitisapolypeptidewithabout92aminoacids.ItisastructuralanalogueofasubunitofFSH.LHandHCG.Bsubunitisapolypeptidemadeupof118aminoacids.GnRH(GonadotropinreleasingHormone)isadecapeptidewith10aminocids.FSHisaglycoproteinwithtwosubunits-aandp.asubunitisapolypeptidewithabout96aminoacids.ItisastructuralanalogueofasubunitofTSH.LHandHCG.psubunitisapolypeptidemadeupof111aminoacids.
376.Lefthandedhelixisseenin- a)BDNA b)ADNA c)ZDNA d)FDNA CorrectAnswer-CAns.is'c'i.e.,ZDNABasedonquartenarystructureofDNAmanyconformationsarepossibleoutofthecommonthreeformsare?BDNA,ADNAandZDNA.ZDNAItisfoundinthoseregionsofchromosomeswhicharerichinGCsequencesItisalefthandedhelixEveryfullturnhas12basepairing.
377.DNAfragmentsareseparatedby? a)Ultracentrifugation b)Agarosegelelectrophoresis c)Paperchromatography d)Highpressureliquidchromatography CorrectAnswer-BAns.is'b'i.e.,Agarosegelelectrophoresis[RefEssentialsofbiochemistryp.756]DNAiscutintolargefragments,usingrestrictionenzymes.Thesefragmentsarethenseparatedbygelelectrophoresis(eitheragaroseorpolyacrylamidegelelectrophoresis).
378.CarbamoylPhosphatesynthetaseI [CPSI]trueis a)Itispresentincytoplasm b)Itisinvolvedinpyrimidinesynthesis c)N-AcetylGlutamateisanallostericstimulatorofCPSI d)GlutamineistheaminogroupdonorforCPSI CorrectAnswer-CAns.is'c'i.e.,N-AcetylGlutamateisanallostericstimulatorofCPSI PROPERTY CPS-I CPS-II Pathway Ureacycle Pyrimidinesynthesis Subcellular Mitochondria Cytoplasm locationAminoGroup Ammonia Glutamine donor Inhibitedbytheproducts- Allosteric StimulatedbyN- pyrimidinenucleotides,Uridine,Cytidine regulation AcetylGlutamate(NAG) &Thymidine
379.Molecularmimicryisestablishedinthe presenceof? a)Cysteine b)Alanine c)Glycine d)Tryptophan CorrectAnswer-AAns.is'a'i.e.,CysteineMolecularmimicryiscausedbystructuralhomologyorsimilaritybetweenforeignantigensandself-antigens.AsaresultofstructuralsimilarityaTcellorBcellactivatedagainstaforeignantigencrossreactswithself-antigenandcausesautoimmunity.Molecularmimicrydoesnotalwaysexpectasequencesimilaritytogetinitiated.ItisfoundtobeinducedevenwhentheselfantigensandexogenousantigenssharethesamebindingmotifwithMHC(MajorHistocompatibilityComplex).Thisbindingmotifsimilarityismoreoftenfoundinthepresenceofcysteine(formsdisulphidebridges),arginineorlysine(formhydrogenbonds)inthebindingsiteofantigens.
380.Allofthefollowingcandetermineprotein structureexcept a)Edman'sSequencing b)Xraycrystallography c)Opticalrotatorydispersion d)Spectrophotometry CorrectAnswer-DAns.is'd'i.e.,SpectrophotometryMethodsusedforstudyingprimarystructure:A)Sanger'ssequencingSanger'sreagentis(1fluro2,4Dinitrobenzene)B)Edman'sSequencingEdman'sreagentisPhenylisothiocyanateC)ReverseSequencingIthastobesupplementedbyMassSpectrometryMethodsusedforstudyingsecondarystructure: 1. OpticalRotatoryDispersion2. OcularDichorism Methodsusedforstudyingtertiarystructure: 1. X-rayCrystallography2. UVspectroscopy3. NMRspectroscopy
381.Edman'sreagentisusedfor a)DNAsequencing b)Proteinsequencing c)ProteinDenaturation d)DNAdenaturation CorrectAnswer-BAns.is'b'i.e.,ProteinsequencingEdman'sreagentisPhenylisothiocyanate.PhenylisothiocyanateisusedforsequencingproteinsPhenylisothiocyanatebindstoaaminogroups.Inaprotein,onlyaminoterminalaminoacid'saaminogroupwillbefree.HencewhenPhenylisothiocyanateisaddedtoapeptidewhichisadsorbedontoaglassfibrecoatedwithapolymer,inthepresenceof12%trimethylamine,itreactswiththeaminegroupofNterminalaminoacid.Byacidhydrolysis,thefirstaminoacidiscleavedfromthepolypeptidechainandtheaminoacidisidentifiedbychromatography.Thecycleiscontinued.Thisway50aminoacidscanbesequenced.
382.Mostabundantaminoacidinbrainis a)Glutamate b)Aspartate c)Glutamine d)Asparagine CorrectAnswer-AAns.is'a'i.e.,GlutamateGlutamateisthemostabundantfreealphaaminoacidfoundinBrain.Itisanacidicpolaraminoacid.Itisthepredominantexcitatoryneurotransmitterofbrain.ItissynthesisedinbrainfromglutamineandaKetoglutarate.Glutamateisreleasedfrompresynapticexcitatoryneuronsinacalciumdependentmanner.Glutamateactsonbothinotropicandmetabotropicreceptors.Inotropicreceptorsofglutamateinclude:KainatereceptorsAMPAreceptorsNMDAreceptors
383.Cystinehashowmanymoleculesof cysteine? a)1 b)2 c)3 d)4 CorrectAnswer-BAns.is'b'i.e.,2CysteineisasulphurcontainingaminoacidItisapolarbutunchargedaminoacidCysteinewithasulfhydrylgroupcangetoxidisedandformsadimer(2)calledascystine.Cysteineacquiresitspolarnatureonlybyvirtueofitssulfhydrylgroup.
384.Jumpinggenesare? a)Moderatelyrepetitivesequences b)Highlyrepetitivesequences c)Satellitesequences d)Simplesegmentrepeatsequences CorrectAnswer-AAns.is'a'i.e.,Moderatelyrepetitivesequences
385.Vitamingiveninhomocysteinuriaareall except a)VitaminB6 b)VitaminB12 c)Folate d)Thiamine CorrectAnswer-DAns.is'd'i.e.,ThiamineMajorfateofhomocysteineisthatitgetsconvertedintocysteineinthepresenceofcystathionineIsynthase.Cystathioninepsynthaseisdependentonpyridoxalphosphate.Hencedefectofcystathioninepsynthasecanresultinhomocysteinuria.Thisiscalledasclassicalhomocysteinuria.ThisconditionrespondstoB6administration,astheenzymecystathionepsynthaseisdependentonB6.Minorfateofhomocysteineisthatitgetsconvertedintomethionineinthepresenceofmethioninesynthase.Methioninesynthaseisdependentonmethylcobalamine(coenzymeformofVitaminB12).MethylgroupdonorformethylcobalamineismethylTHFA.Homocysteinuriaisalsocausedbydefectofmethioninesynthase.AsthisenzymeisdependentonVitaminB12andTHFA,homocysteinuriarespondstoB12andTHFAadministration
386.Glutathioneisusedtodetoxifywhich freeradical? a)Hydrogenperoxide b)Superoxide c)Peroxylradical d)SingletOxygen CorrectAnswer-AAns.is'a'i.e.,HydrogenperoxideGlutathioneisatripeptide.ItisgammaglutamylcysteinylglycineItisdenotedasGSH-becauseithascysteinewithasulphydrylgroupItisusedtodetoxifyhydrogenperoxideandlipidperoxidesinthepresenceofglutathioneperoxidase.Glutathionecanalsodetoxifyperoxylradical.Peroxylradicalcannotgetreducedbyenzymaticreactions.TheygetdetoxifiedbyantioxidantslikevitaminEandGlutathioneSingletoxygengetsdetoxifiedprincipallybypolyphenolantioxidantsSuperoxideradicalsaredetoxifiedbySuperoxidedismutase(SOD)usingZincaselectronacceptorordonor(SomeclassesofSODsuseironorNickelaselectronacceptorordonor)
387.Ataxiatelangiectasiaiscausedbya defectof? a)BaseExcisionRepair b)NucleotideExcisionrepair c)Mismatchrepair d)dsDNAbreakrepair CorrectAnswer-DAns.is'd'i.e.,dsDNAbreakrepair DNArepair Defectassociated Mismatchrepair HereditaryNonpolyposisColonCancer NucleotideExcision Xerodermapigmentosa,Cockayne Repair syndrome DoubleStrandedDNA AtaxiaTelangiectasia,Bloom's Break syndrome, Repair Fanconi'sanemia
388.Bondformationbetweenribosesugar andnitrogenis? a)Acidanhydridelinkage b)Phosphodiesterlinkage c)Phosphoesterlinkage d)Glycosidiclinkage CorrectAnswer-DAns.is'd'i.e.,GlycosidiclinkagePentosesugar(riboseordeoxyribose)islinkedtoanitrogenousbase(purineorpyrimidine)viacovalentN-glycosidicbondtoformnucleoside
389.Thelinkagewhichlinksindividual nucleotidesinapolynucleotidechainis- a)pN-Glycosidiclinkage b)aN-glycosidiclinkage c)3'5'Phosphodiesterlinkage d)5'3'Phosphodiesterlinkages CorrectAnswer-CAns.is'c'i.e.,3'5'Phosphodiesterlinkage Nucleoside N-glycosidicbondbetweenpentosesugarandnitrogenousbase. Nucleotide Posphoesterlinkage(notphosphodiester) (monophasphate betweennucleosideandphosphategrp. nucleatide)Diphosphate& Acidanhydridelinkagebetween polyphosphate monophosphate&otherphosphategrp nucleotidesPolynucleotidechain 3'5'phosphodiesterlinkagebetween3'hydroxylgroupnucleotidewith5'phosphategroupofnextnucleotide.
390.Allofthefollowingaretrueabout NucleicAcidSequenceBasedAmplificationexcept? a)ItisaspecificamplificationofRNA b)ItisareplacementforreversetranscriptasePCR c)Denaturationiscarriedoutat94?C d)ItrequiresReversetranscriptase. CorrectAnswer-CAns.is'c'i.e.,Denaturationiscarriedoutat94?CNucleicAcidSequenceBasedAmplification(NASBA)orIsothermalRNAamplificationisareplacementforReversetranscriptasePCR(RT-PCR).BothNASBAandRT-PCRareusedforamplifyingdesiredorspecificRNAfragments.InRT-PCR,firstthedesiredRNAisconvertedtodsDNAusingreversetranscriptaseandthenthedsDNAisamplifiedusingPCRtechnique
391.RegardingFISHallaretrueexcept? a)Usedtodetectcopynumbervariations b)Usedtodetectbalancedtranslocations c)Requiresoligonucleotides d)RequiresDNApolymerase CorrectAnswer-DAns.is'd'i.e.,RequiresDNApolymeraseFluoroscentinSituHybridisationisacytogenetictechniqueusedtodetectchromosomalabnormalities.ThistechniqueusesfluorescentlylabelledoligonucleotidesorDNAprobes.Theseprobesbindtospecificsequencesofachromosome.Attachedtotheprobesarereporterfluorescentdyeswhichunderfluorescencemicroscopyconfirmthepresenceorabsenceofaparticularchromosomalaberration.InFISH,thetargetisthenuclearDNAofeitherinterphasecellsorofmetaphasechromosomesaffixedtoamicroscopeslide.Whenaspecificprobeisadded,itannealstoitscomplementarysequenceintheaffixedDNA.Astheprobeislabelledwithareportermoleculeitisvisualizedbyfluorescencemicroscopy
392.Trueaboutpyrimidinecatabolismis? a)Itisasourceofuricacid b)aminoisobutyrateisgenerated c)Unlikeothercatabolicpathways,itdoesnotgenerate intermediatesofcitricacidcycle d)Increasedpyrimidinecatabolismcausesdecreasedsynthesisof carnosine CorrectAnswer-BAns.is'b'i.e.,aminoisobutyrateisgeneratedInpyrimidinecatabolism,firstcytidineandthymidineareconvertedtouridinebydeaminationanddemethylationrespectively.Uridineinthepresenceofphosphorylasegetsconvertedintouracil.UracilundergoeshydrogenationinthepresenceofdihydrouracildehydrogenasetoformdihydrouracilDihydrouracilhydrataseopenstheringofdihydrouraciltoformalinearstructure
393.TrueaboutPurinesynthesis? a)GlutamineistheaminogroupdonorforN9 b)PRPPsynthetaseistheratelimitingenzymeofpurinesynthesis c)THFAisnecessaryforformingC6ofpurinering d)GMPisthefirstnucleotidetobeformedduringpurinesynthesis CorrectAnswer-AAns.is'a'i.e.,GlutamineistheaminogroupdonorforN9Inpurinenucleotidesynthesis,firstRibose5phosphateisactivatedbyPRPPsynthetasetoformPRPP.ThisPRPPgetsattachedtoN9(sourceisglutamine)inthepresenceofPRPPglutamineamidotransferase.Thisistheratelimitingenzymeofpurinesynthesis.PRPPsynthetaseisacommonenzymeofpyrimidinenucleotidesynthesisandofniacinadeninedinucleotidesynthesis.AsPRPPsynthetaseisnotcommittedforPurinenucleotidesynthesis,itcannotbeconsideredastheratelimitingenzymeofpurinesynthesis.Inpurinesynthesis,Inosinemonophosphate(IMP)isfirstformedIMPonaminationwithAspartategivesrisetoAMPinthepresenceofadenylosuccinatesynthetase.ThisstepneedsGTPasasourceofenergyIMPondehydrogenationbyIMPdehydrogenasefollowedbyaminationwithglutaminewillgiverisetoGMP.ThisstepusedATPasasourceofenergy
394.AntistressVitaminis? a)VitaminB1 b)VitaminB2 c)VitaminB3 d)VitaminB5 CorrectAnswer-DAns.is'd'i.e.,VitaminB5VitaminB5orpantothenicacidiscalledasanantistressvitaminasitisfoundtohaveanimpactoncortisolreleaseandisfoundtosupportourimmunesystem.
395.Matchenzymewiththediseasecaused duetoitsdeficiency- Enzyme DiseaseA.TyrosinemiaTypeII Fumarylacetoacetate hydroxylase Tyrosinetransaminase B.HomogentisateOxidase Tyrosinase C.TyrosinemiaTypeI Alkaptonuria D-Albinism a)ID,2C,3A,4B b)IA,2C,3D,4B c)1C,2D,3A,4B d)lC,2A,3D,4B CorrectAnswer-DAns.is'd'i.e.,1-pC,2A,3D,4B[RefHarper29th/ep.289]
396.RegardingNADandNADP,trueis? a)Precursoristyrosine b)MalicenzymeisanNADdependentenzyme c)Highleucinecausesniacindeficiency d)Niacindeficiencycausescutaneousvasodilatation CorrectAnswer-CAns.is'c'i.e.,HighleucinecausesniacindeficiencyNADandNADParenicotinicacidderivativeswhichissynthesizedfromtryptophan(nottyrosin)MalicenzymeisNADPdependentenzyme(notNADdependent)Excessofleucineinhibitstheconversionoftryptophanintoniacinandcausespellagra.NiacindeficiencycausesPellagra.PellagracharacterisedbythethreeDs-Diarrhoea,DermatitisandDementiaiscausedbyniacinorvitaminB3deficiency.
397.Whichofthefollowinghastwoamino groups- a)Glycine b)Arginine c)Lysine d)Asparagine CorrectAnswer-BHistidinehastwoiminogroups.Lysinehasoneaminogroup.Argininehastwoaminogroups
398.Deficiencyofwhichvitaminduring pregnancypredisposestomeningomyelocele? a)Folicacid b)Biotin c)Pyridoxine d)Thiamine CorrectAnswer-AAns.is'a'i.e.,FolicacidFolicaciddeficiencyinpregnancypredisposedtoNTD(e.g.myelomeningocele,meningocele,spinabifida).
399.VitaminB12deficiencycausesallexcept ? a)Homocysteinuria b)Methylmalonicaciduria c)Subacutecombineddegeneration d)Epinephrineexcess CorrectAnswer-DAns.is'd'i.e.,Epinephrineexcess[RefDineshPuri3rdlep.381]DeficiencyofvitaminB12causesPerniciousanemia,megaloblasticanemia(secondarytofunctionalfolatedeficiencyduetofolatetrap),methylmalonicaciduriaduetoaccumulationofmethylmalonyl-CoA,andneuropathy,likesubacutecombineddegeneration(SACD)anddemyelination.Theremayhomocysteinuriaasmethioninesynthase,amethylcobalaminedependentenzyme,isdefective.
400.Alternatefuelforbrainis a)Glucose b)Ketonebodies c)Fattyacid d)Aminoacid CorrectAnswer-BAns.is'b'i.e.,KetonebodiesThereisnostoredfuelinbrain,butitutilizes60%oftotalenergyunderrestingconditions.Glucoseisvirtuallythesolefuelforthebrain,exceptinprolongedstarvingwhenketonebodiesarethemajorsource.Fattyacidsdonotserveasfuelforthebrain,becausetheyareboundtoalbumininplasma;hencecannotcrosstheblood-brainbarrier.
401.Pyruvatecanbeasubstrateofallexcept a)LactateDehydrogenase b)Malicenzyme c)Aspartatetransaminase d)Alaninetransaminase CorrectAnswer-CAns.is'c'i.e.,AspartatetransaminaseThereareseveralpathwaysintowhichpyruvatecanenter.Thepathwaychoseninagiventissuedependsonitsstateofoxygenationandprevailingmetabolicconditions,asdescribedbelow:OxidativedecarboxylationtoacetylCoAIntissuesthatareadequatelyperfusedwithoxygen(i.e.,underaerobicconditions),pyruvateundergoesoxidativedecarboxylationtoformacetylCoA,whichisfurthercatabolizedtoCO2andH20viacitricacidcycle(Krebscycle).ThisreactionservesasabridgebetweenglycolysisandKreb'scycle.Thus,pyruvateservesasthesourceofsubstrateoffirstreactionofTCA(Citricacidcycle),i.e.,acetylCoA.
402.Whichofthefollowingelementsis knowntoinfluencethebody'sabilitytohandleoxidativestress? a)Fluride b)Iron c)Copper d)Selenium CorrectAnswer-DAns.is'd'i.e.,Selenium[Ref:PankajNaikp.382]Theactivityoftheantioxidantenzymesdependsonsupplyofminerals:?*Manganese*Zinc*Copper*Selenium-Manganese,copperandzincarerequiredfortheactivityofsuperoxidedismutase.-Seleniumisrequiredfortheactivityofglutathioneperoxidase.
403.Gasreleasedfromoligosaccharide metabolismbyintestinalbacteriais a)Carbondioxide b)Sulphurdioxide c)Nitricoxide d)Methane CorrectAnswer-DAns.is'd'i.e.,MethaneSomefooditemsarehighinindigestibleoligosaccharides.Eg,transgalactooligosaccharides,fructooligosaccharides(Inulin)Sincetheseoligosaccharidesdonotgetdigestedinthesmallintestine,theyreachthelargeintestine.Largeintestinalmicroorganismsbreakdowntheseoligosaccharidestoformshortchainfattyacidslikepropionate,butyrate.Theseshortchainfattyacidsarefoundtobetrophictointestinalmucosa.Ithasanti-inflammatoryeffectstoo.Hencethesearefoundtoprotectintestinalmalignancy.Thisisthebasisofprebioticsbeingsupplementedtopeoplewithintestinalinflammatorydisordersandtomaintainintestinalflora.Butthedownsideoftheseindigestibleoligosaccharidesisthat,whenmicroorganismsactontheseoligiosaccharides,theyresultingasproduction.Thegasesproducedincludestheusualhydrogen,nitrogenandcarbondioxide.Apartfromthatwhenoligosaccharidesareacteduponbymicroorganisms,itresultsinmethaneproduction.Thismethaneisfoundtohavethebloatingandflatulenceeffect.
404.Chainbreakingantioxidantsareall except- a)Tocopherol b)Ascorbicacid c)Polyphenolicflavinols d)Superoxidedismutase CorrectAnswer-DAns.is'd'i.e.,SuperoxidedismutaseChainbreakingantioxidantsaremoleculeswhichcandonateanelectronoracceptelectronfromunstableintermediatesoflipidperoxidationconvertingthemintostableintermediates.TheyareoftwotwotypesLipidphasechainbreakingantioxidantAqueousphasechainbreakingantioxidantLipidphasechainbreakingantioxidantThemostimportantlipidphasechainbreakingantioxidantisatocopherol.atocopherolreactswithperoxylradicaltoformtocopheroxylradicalwithexcesschargeassociatedwithextraelectronbeingdistributedalongthechromanering.AqueousphasechainbreakingantioxidantThemostimportantchainbreakingantioxidantofthistypeisascorbicacidorvitaminC.Itcanscavengemanysuperoxideradicals.Mostimportantlyithelpsbyregeneratingtocopherolafteritisoxidisedduringtheprocessofreducingperoxylradicals.ApartfromvitaminCwehaveagroupofpolyphenolflavinolslikeepitachingallatewhichcanreduceoxidantspeciesinaqueousphase.Thesearepresentingreenteaandsomeantioxidantsupplements
Superoxidedismutaseisanantioxidantenzymewhichhelpsindetoxifyingsuperoxidestoformmolecularoxygenandhydrogenperoxide.Itisnotachainbreakingantioxidant
405.Whichvitaminisrequiredforconversion ofserinetoglycine? a)VitC b)B12 c)Pyridoxine d)Thiamine CorrectAnswer-CAns.is'c'i.e.,Pyridoxine[RefHarper290/ep.267-268]GlycineisanonessentialaminoacidsynthesizedfromanothernonessentialaminoacidserineSerineinthepresenceofSerinehydroxylmethyltransferase(SHMT)getsconvertedtoglycine.SHMTisapyridoxinedependentenzyme.ThisstepusestetrahydrofolateascoenzymeanditgetsconvertedtoN5,N10methyleneTHFA,whichthenactsas1carbondonorandhelpsintheconversionofuridinetothymidine.
406.Whichofthefollowingvitaminsis significantlysynthesisedingutbyintestinalflora? a)Folate b)B12 c)Biotin d)B6 CorrectAnswer-A:B:CAns.is'c>'b'&'a'i.e.,Biotin>B12&FolateThoughvitaminsaresupposedtobeessentialmicronutrientswhicharesupposedtobesuppliedinthediet,somevitaminslikeVitaminDandNiacinareendogenouslysynthesised.VitaminD3orcholecalciferolissynthesisedintheskinepidermiswhenUVlightactson7dehydrocholesterolwhichispresentinthemalphigianlayer.UVlightopensuponeoftheringsofcholesterol,convertingcholesterolintoasecosteroidwhichischolecalciferol.Cholecalciferolreachesliver.Inliveritishydroxylatedat25thpositionby25ahydroxylasetoform25hydroxycholecalciferol25hydroxycholecalciferolreachesthekidney.Itishydroxylatedat1stpositionby1ahydroxylasetoform1,25dihydroxycholecalciferol,theactiveformofvitaminD.Niacin'sactivecoenzymeformsNADandNADParesynthesisedendogenouslyfromaminoacidtryptophanApartfromthesetwovitaminssynthesisedbyhumanmetabolicpathways,therearevitaminslikeBiotin,VitaminKwhicharesynthesisedtosignificantamountinlargeintestinebyintestinalmicroorganisms.ResearchhasidentifiedsynthesisoffolateandB12
aswellinlargeintestine.Thoughtheyaresynthesisedinlargeintestine,asallwatersolublevitaminsgetabsorbedinsmallintestine,onlyendogenouslysynthesisedBiotinandVitaminKarefoundtocontributesignificantlytometabolicpathways.ThatiswhybiotinandvitaminKdeficienciesarerelativelyrare.
407.Headacheandpapilledemaarefeatures oftoxicityofwhichvitamin? a)VitaminA b)VitaminD c)VitaminC d)VitaminE CorrectAnswer-AAns.is'a'i.e.,VitaminAHypervitaminosisACausedbyconsumptionoffoodrichinvitaminAlikefishorliver(notbyexcessiveintakeofcarotenoidsastheconversionofcarotenetovitaminAisregulated).Mechanismoftoxicity:Suppressesosteoblastsandstimulatesosteoclasts.Highretinolconcentrationsstimulatelysosomalenzymereleaseandcauselocaltissuedamage.Featuresincludeanorexia,irritability,headache,skinpeeling,vomiting.Headache,vomitingandpapilledemaarefoundtobecausedbyincreaseinintracranialtension.Hencethisconditioniscalledaspseudotumourcerebri.AsvitaminAstimulatesosteoclasts,hypercalcemia,bonyprojections,pathologicalfracturesarealsoobservedasfeatures.
408.VitaminB12isrequiredforallofthe followingexcept? a)Conversionofhomocysteinetomethionine b)Conversionofhomocysteinetocysteine c)ConversionofpropionylcoAtosuccinylCoA d)ConversionofmethylTHFAtoTHFA CorrectAnswer-BAns.is'b'i.e.,ConversionofhomocysteinetocysteineActiveformofvitaminB12aremethylcobalamineanddeoxyadenosylcobalamine.FollowingreactionsrequirevitaminB12coenzyme:i)IsomerizationofmethylmalonylCoAtosuccinylCoA:Inthisreaction,activeformofvitaminB12isdeoxyadenosylcobalamine.Propionyl-CoAisproducedascatabolicendproductofsomealipathicaminoacidsand(3-oxidationofoddchainfattyacids.PropionylCoAisthenconvertedtosuccinylCoAthroughmethylmalonyl-CoA.Thusmethylmalonyl-CoAisaccumulatedandexcretedinurineasmethylmalonicacid(methylmalonate)invitaminB12deficiency,i.e.methylmalonicaciduria.ii)ConversionofhomocysteintomethionineInthisreaction,activeformismethylcobalamine.Thisistheonlyreactionwhichrequiresbothvitamin812(asmethylcobalamine)andfolicacid(asN5-methyl-114-folate).Thereactioniscatalyzedbytheenzymecobalamin-dependentmethioninesynthasealsocalled5-methyltetrahydrofolate-
homocysteinemethyltransferase.
409.Alcoholismleadstodeficiencyofwhich vitamin? a)VitaminA b)VitaminB1 c)VitaminD d)VitaminB6 CorrectAnswer-BAns.is'b'i.e.,VitaminB1Ofallthemicronutrients,thiaminewillbethefirstmicronutrienttobecomedeficient.Reasonis,apartfromthepersonmissinghismixedbalanceddiet,alcoholisalsofoundtointerferewiththiamineabsorption.Thethirdreasonrelatedtothiaminedeficiencyinachronicalcoholicisthatalcoholinterfereswithmagnesiumabsorption.Magnesiumisnecessaryforactivationofthiaminetoitscoenzymeformthiaminepyrophosphateinthepresenceofthiaminekinase.
410.AST/ALT>2occursindeficiencyof a)Glucose-6-phosphotase b)Branchingenzyme c)Acidmaltase d)Liverphosphorylase CorrectAnswer-CAns.is'c'i.e.,Acidmaltase[RefReadbelow]Inliverdiseases,ALT(alaninetransaminase)iselevatedmorethanAST(aspartatetransaminase).So,inliverdiseasesALT/ASTratioiselevated.But,whenASTishigherthanALT,amuscle,sourceoftheseenzymesshouldbeconsidered.Amongthegivenoptions,onlyacidmaltasedeficiency(Pompe'sdisease)ismyopathicformofglycogenstoragedisease(muscularglycogenosis).Thus,AST/ALTratiomaybemorethan2.Otherthreeoptionsareliverglycogenoses(AST/ALT<1,asALTisraisedmorethanAST).
411.LDHhashowmanyisoenzymes a)3,basedonBandMpolypeptidesubunits b)5,basedonBandMpolypeptidesubunits c)7,basedonHandMpolypeptidesubunits d)5,basedonHandMpolypeptidesubunits CorrectAnswer-DAns.is'd'i.e.,5,basedonHandMpolypeptidesubunitslRef:Dineshpuri3'd/ep.1221LDHisatetramerwithtwotypesofpolypeptideunits:(H)(forheart)andM(formuscle).lthasfiveisoenzymes:LDH1(HHHH),LDH2(HHHM),LDH3(HHMM),LDH4(HMMM),andLDHs(MMMM).LDH-IandLDH-2arethepredominantisozymesinmyocardium,thereforetheseareraisedinMI(LDHf>LDH2),LDH-fismorespecificformyocardium(asithas4H)thanLDH-2.ThepredominentisoenzymeinliverisLDH5;HenceLDH5israisedinliverdiseaseslikeviralhepatitis.NormalLDHpatternonelectrophoresisisLDH2>LDHI>LDH3>LDH4>LDH5.InMILDHIisraisedmoretharLDHz,So,patternbecomesLDHI>LDH2>LDH3>LDH4>LDH5.IncreaseintotalLDHlevelisalsoseeninhemolyticanemia,hepatocellulardamage,musculardystrophies,leukemia,carcinomas,cerebrovascularaccident,pancreatitis,kidneydisease,intestinalandpulmonaryinfarction,megaloblasticanemiaandinfectiousmononucleosis.Thereforestudyofspecific
isozymeismoresignificant.
412.Exampleofallostericinhibition a)Inactivationofglycogensynthasebyphosphorylation b)Decreasedsynthesisofglucokinasebyglucagon c)InhibitionofPFK-1bycitrate d)Alloftheabove CorrectAnswer-CAnswer-Ans.is'c'i.e.,InhibitionofPFK-lbycitrate[lRef,Dineshpuri3d/ep.1161]Enzyme:-PhosphofructokinaseIPathway:-GlycolysisStimulator:-AMP,ADP,fructose-6-phosphaie,fuctose-2,6-bisphophate.Inhibitor:-ATP,citrate,Ca2+,Mg+
413.Lysyloxidaserequireswhichcofactor- a)Zn b)Cu c)Se d)Fe CorrectAnswer-BAns.is'b'i.e.,Cu[RelHarper27t'/ep.546] metal metalloenzymes Calcium Lipase,LecithinaseCytochromeoxidase,Tyrosinase,Lysyloxidase, Copper Superoxidedismutase,Ascorbicacidoxidase,Ferroxidase(ceruloplasmin)Cytochromeoxidase,Xanthineoxidase,Catalase, iron PeroxidaseCarbonicanhydrase,alkalinephosphatase,RNApolymerase,alcoholdehydrogenase, Zinc Carboxypeptidase,Prophobilinogensynthase,glutamatedehydrogenase,lactatedehydrogenase,SuperoxidedismutaseHexokinase,phosphofructokinase,glucose-6- Magnesium phosphatase,enolase,creatininekinase, Phosphatases,kinaseArginase,Pyruvatecarboxylase,phosphoglucomutase, Manganese Glycosyltransferase,Hexokinase,EnolasePotassium Pyruvatekinase Selenium Glutathioneperoxidase Nickel Urease molybednum Xanthineoxidase
molybednum Xanthineoxidase
414.Mechanismofconversionoftrypsinogen totrypsin- a)Hydrolysis b)Phosphorylation c)Removalofpartofprotein d)RemovalofCarboxylgroup CorrectAnswer-CAns.is'c'i.e.,Removalofpartofprotein[Ref:Dineshpuri3'd/ep-1181Allzymogens(includingtrypsinogen)areactivatedbyremovalofasmalllengthofprotein(fewaminoacids)fromoneendofthemolecule.TrypsinogenTrypsin+peptidefragentPepsinogenpepsin+peptidefragment
415.TrueaboutNADP- a)ActsascoenzymeformofNiacin b)InvolvedinHMPshunt c)Notinvolvedinglycolysis d)Allaretrue CorrectAnswer-DAns.is'd'i.e.,AllaretrueNiacin,intheformofnicotinamide,isincorporatedintothestructureoftwocoenzymes:nicotinamideadeninedinucleotide(NAD+)andnicotinamideadeninedinucleotidephosphate(NADP+)NADPisinvolvedinHMPshuntandNAPDHisproduced.InglycolysisNADisinvolved(notNADP).
416.Inmalateshuttle,NADHProduceshow manyATPs a)1 b)1-5 c)2 d)2.5 CorrectAnswer-DAns-is'd'i.e.,2.5(Ref:Harp*2*/ep.129-130)Inglycerophosphateshuttle,themitochondrialennlmeislinkedtorespiratorychain(ETC)viaaflavoprotein,Soonlyl.5molofATPareproduced(Accordingtooldercalculations,2ATPmolofATPareproduced).Inmalateshuttle,themitochondrialenzymeislinkedtoETCviaNAD,so2.5molofATPareproduced(accordingtooldercalculations3molofATPareproduced).
417.Pyruvatedehydrogenaserequiresall cofactorsexcept a)Thiamin b)Riboflavin c)Niacin d)Pyridoxin CorrectAnswer-DAns.is'd'i.e.,Pyridoxin[RefHarper29thlep.176]PyruvatedehydrogenasecatalysesoxidativedecarboxylationofpyruvatetoacetylCoA.ThecoenzymerequiredbyPDHare:- 1. Thiaminepyrophosphate2. Riboflavin(FAD)3. CoA4. Niacin(NAD)5. Lipoicacid
418.Lactateproducedanaerobicallyisused by a)Gluconeogenesis&Glycolysis b)Coricycle&gluconeogenesis c)TCAcycle&Glycogenolysis d)Coricycleonly CorrectAnswer-BAns.is'b'i.e.,coricycle&gluconeogenesis[RefLehninger4h/ep.523,53g-391CoricycleorlacticacidcycleAnaerobicglycolysisinmusclesresultsintheproductionoflactate,whichcannotbeconvertedintoglucose,asgluconeogenesisdoesnotoccurinmuscles.Throughblood,Lactateistransportedtotheliverwhereitisoxidizedtopyruvate.pynrvatesoproduced,isconvertedtoglucosebygluconeogenesis,whichisthentransportedtothemuscle.Theglucosethusreformedfromlactateagainbecomesavailableforenergypurposeinskeletalmuscle.
419.Citratesynthaseisinhibitedby- a)ATP b)ADP c)Insulin d)Glucagon CorrectAnswer-AAns.is'a'i.e.,ATP[RefChatterjee&ShindeVh/ep.171,166-180;Harper28th/ep.145-147
420.Fumarateisformedfromwhichamino acid a)Methionine b)Valine c)Histidine d)Tyrosine CorrectAnswer-DAns.is'd'i.e.,Tyrosine[RefHarper29th/ep.166-67]Allmajormembersofthecitricacidcyclefromcitratetooxaloacetateareglucogenicandtherefore,areinvolvedingluconeogenesis.SomeglucogenicaminoacidsenterstheTCAcycleaftertransaminatione.g.: 1. Histidine,proline,glutamineandarginineareconvertedtoglutamate whichisthentransaminatedtoa-ketoglutarate. 2. Isoleucine,methionineandvalineenterbyconversionintosuccinyl CoA.Propionate(ashortchainfattyacid)alsoenteratthislevel. 3. Tyrosine,andphenylalanineenterbyconversionintofumarate.4. Tryptophanisconvertedtoalaninewhichisthentransaminatedto pyruvate. 5. Hydroxyproline,serine,cysteine,threonineandglycineenterby conversionintopyruvate.
421.Themajorroleof2,3 bisphosphoglycerateinRBCsis- a)Acid-basebalance b)Reversalofglycolysis c)Releaseofoxygen d)Bindingofoxygen CorrectAnswer-CAns.is'c'i.e.,ReleaseofOxygen[RefLehningerilthiep.171]RapoportLueberingcycle(Bisphosphoglycerateshunt)Thiscycleoccursinerythrocytes(ABCs).InthisproductionofATPbysubstratephosphorylationfrom1,3-BPGisbypassedbytakingdiversionpathways,i.e.,sidereactionofglycolyticpathway.Inthiscycle,1,3-BPGisconvertedto2,3BPGbyanenzymebisphosphoglyceratemutase.Then2,3BPGisconvertedto3-phospholycerateby2,3-bisphosphoglyceratephosphatase.
422.EnzymedeficientinHersdisease- a)Musclephosphorylase b)Liverphosphorylase c)Acidmaltase d)Debranchingenzyme CorrectAnswer-BAns.isB'i.e.,Liverphosphorylase[RefHarper250/ep.181] Organ(s) Type Enzymedeficiency affected vonGierke's I Glucose6-phosphatase Liver,kidney disease alpha(14)Glucosidase II Pompe'sdisease Allorgans (acidmaltase) Cori's III disease/Forbe's Debranchingenzyme Muscle,liver disease Liver, IV Andersen'sdisease Branchingenzyme myocardium V McArdle'sdisease Phosphorylase Muscle VI Hers'disease Phosphorylase LiverMuscle, VII Tarui'sdisease Phosphofructokinase RBCs VIII Phosphorylasekinase Liver
423.Immediatemetabolicproductsduring conversionofFructus1-6bisphosphateto2moleculesofpyruvate- a)Glyceraldehyde-3-phosphateand1,3-bisphosphoglycerate b)Dihydroxyacetonephosphateand1,3bisphosphoglycerate c)Glyceraldehyde-3-phosphateanddihydroxy-acetonephosphate d)3-phosphoglycerateand1,3bisphosglycerate CorrectAnswer-CAns.is'c'i.e.,Glyceraldehyde-3-phosphateanddihydroxyacetonephosphate(Ref:Harper29h/ep.170-177).
424.Inconversionofglucosetoglucose-6- phosphateinglycolysistrueis a)Glucokinasehaslowkm b)Hexokinaseisfoundonlyinliver c)Glucokinaseisinducedbyinsulin d)Hexokinaseisnotspecificforglucose CorrectAnswer-C:DAns.is'c'i.e.,Glucokinaseisinducedbyinsulin&'d'i.e.,Hexokinaseisnotspecificforglucose(Ref:Harper29h/ep.170-177;Vasudevan#/ep.98)Hexokinaseisnotspecificforglucosemetabolism.Itisfoundinmosttissuesexceptglucose.GlucokinasehashighKM.Itisinducedbyinsulin.
425.Majorcarbohydratestoreinthebody- a)Bloodglucose b)Glycogeninadiposetissue c)Hepaticglycogen d)Noneoftheabove CorrectAnswer-CAns.is'c'i.e.,Hepaticglycogen(Ref:Harper29/ep.161;Dineshpuri3d/ep.320)MajorCarbohydratesourceofbodyishepaticglycogen.Humanscarrysuppliesoffuelwithintheirbody.Caloriesarestoredinthebodyasfat(triglycerides),glycogenandsomeprotein.
426.Mostabundantsourceoffuelin starvation- a)Liverglycogen b)Muscleglycogen c)Adiposetissue d)Bloodglucose CorrectAnswer-CAns.is'c'i.e.,Adiposetissue[RefHarper29thlep.161&28thlep.134,140;Vasudevan6th/ep.84,85]Fat(triglycerides)intheadiposetissueisthelargeststoreofenergyofthebody.
427.Majormetabolismofsaturatedfatty acidsinthemitochondriaiscalledas- a)-oxidation b)-oxidation c)-oxidation d)Noneoftheabove CorrectAnswer-AAns.is'a'i.e.,-oxidation[RefHarper29"'/ep.208]-oxidationistheprincipalpathwayforcatabolismofsaturatedfattyacids.P-oxidationmainlyoccursinthemitochondrialmatrix(whereasfattyacidsynthesisoccursincytosol).
428.Whichmethodisusedtoseparatea mixtureoflipids- a)Electrophoresis b)Chromatography c)Isoelectricfocusing d)PAGE CorrectAnswer-BAns.is'b'i.e.,Chromatography[RefClinicalbiochemistryp.719]Extractedlipidsareseparatedintoindividualclassbychromatography.Chromatographycanseparateacomplexmixtureoflipidsintosimplergroup.Varioustypesofchromatography,usedtoseparate,lipidsare-Adsorption(solid-liquid)chromatographyPartition(liquid-liquid)chromatographyThinlayerchromatography(TLC)Gaschromatography(GC)Highperformanceliquidchromatography(HPLC)->methodofchoiceifavailable.
429.Chylomicronscoreisformedby? a)Triglyceride b)TriglycerideandCholesterol c)Triglyceride,CholesterolandPhospholipids d)Freefattyacids CorrectAnswer-BAns.is'B'i.e.,TriglycerideandCholesterol[RefHarper27th/ep.218;Lehninger4th/ep.633]Thesurfaceisalayerofphospholipids,withheadgroupsfacingtheaqueousphase.Triacylglycerolssequesteredintheinteriormakeupmorethan80%ofthemass.Severalapolipoproteinsthatprotrudefromthesurface(B-48,C-III,C-II)actassignalsintheuptakeandmetabolismofchylomicroncontents.Thediameterofchylomicronsrangesfromabout100to500nm.Core:It'smadeupofneutrallipidsliketriacylglycerolsandcholesterol/cholesterolesters.Shell:composedofapolipoproteins,phospholipids.
430.AllaretrueaboutNiemann-Pickdisease except- a)Duetodeficiencyofsphingomyelinase b)CNSsymptomsintypeA c)HistiocytesshowingPASpositiveinclusionsandTypeBisless severe d)None CorrectAnswer-DAns.isD.None[RefClinicalbiochemistry4th/ep.786]Niemann-Pickdiseaseisanautosomalrecessive`lysosomalstoragediseaseduetodeficiencyofsphingomyelinase.CharacteristichistopathologicalfeatureishistiocytesshowingPASpositivediastaseresistantinclusionswhichonmicroscopyshowsconcentricorparrallellamellararrangement.Clinicalcasesaredividedinto- 1. TypeA:Thesearemorecommonwithmoreseveredeficiencyof sphingomyelinase.ThereisvisceralandCNSinvolvement.Symptomsmaypresentsincebirthanddeathusuallyoccursbeforetheageof4years. 2. TypeB:Thereislessseveredeficiencyofsphingomyelinase. Patient'shaveonlyvisceralinvolvementbutnoCNSinvolvement.Patientspresentbytheageof3-4yearswithorganomegalyandmayremainreasonablyhealthy.
431.AcetylCoACarboxylaseisstimulatedby - a)Starvation b)Glucagon c)Citrate d)Alloftheabove CorrectAnswer-CAns.is'c'i.e.,Citrate[RefHarper29th/ep.219] Activator Inhibitor Allosteric(palmitoylCoA) Citrate Longchainacyl-CoA Covalent Insulin Glucagon,epinephrine
432.Cholesterolisnotaprecursorfor synthesisof- a)VitaminD b)Progesterone c)Bileacids d)Lipocortin CorrectAnswer-DAns.is'd'i.e.,LipocortinCholesterolisanimportantprecursorforthesynthesisof:- 1. Steroidhormones:-Progesterone,estrogen,,androgens, glucocorticoids,mineralocorticoids 2. VitaminD3. Bileacids
433.HDLiscalledgoodcholesterolbecause- a)Removescholesterolfromextrahepatictissues b)Causestransportofcholesteroltoextrahepatictissues c)StimulatehepaticTGssynthesis d)Activateslipoproteinlipase CorrectAnswer-AAns.is'a'i.e.,RemovescholesterolfromextrahepatictissuesTheHDLparticlesarereferredtoasscavengersbecausetheirprimaryroleistoremovefree(unesterified)cholesterolfromextrahepatictissues,whichisthenexcretedthroughbile.Thisisacrucialmechanismthatpreventstheinappropriateaccumulationofcholesterolinperipheraltissues.Becauseaccumulationofcholesterolintissuesisstronglyassociatedwiththedevelopmentofatherosclerosis,thelevelofHDLinserumisinverselyrelatedtotheincidenceofMI(myocardialinfarction).Thus,HDLiscardioprotectiveandanti-atherogenicinnature,andisreferredtoas"goodcholesterol".Therefore,HDL-Cholesterolappearstobethebestindependentpredictorofcoronaryarterydisease(inverserelationship)thananyotherknownriskfactor.ThatmeanslowHDLisamuchstrongerpredictorofcoronaryarterydiseasethanincreasedLDLcholesterolorincreasedtotalcholesterol.
434.
Amidegroupispresentinwhichpartofprotein- a)Amino-terminal b)Carboxy-terminal c)Peptidebond d)Disulfidebond CorrectAnswer-CAns.is'c'i.e.,Peptidebond[RefTextbookofbiochemistrybyTalwar-p.30]Apeptidebondisachemicalbondthatconnectsaminoacidstoeachother.Apeptidebondessentiallyresultsfromadehydrationsynthesisreaction.Itisformedbetweentwoaminoacidswhenthecarboxylgroupofoneaminoacidreactswiththeaminogroupoftheother,releasingamoleculeofwater(H20).PeptidebondistheresultingCO-NHbondandtheresultingmoleculeisanamide.Thefour-atomfunctionalgroup-C(=0)NH-iscalledanamidegrouporpeptidegroup.Peptidebondisapartialdoublebond.Partialdoublebondnaturerenderstheamidegroupplanarandrigid,makingalltheatomsthatareinvolvedinthepeptidebondlieinaflatplane.
435.Non-essentialamino-acidsareallexcept - a)Basicaminoacids b)Acidicaminoacids c)Neutralaminoacids d)Noneoftheabove CorrectAnswer-AAns.is'a'i.e.,Basicaminoacids[RefHarper29th/ep.266]There,arethreebasicaminoacids(Arginine,Histidineandlysine),allofthemareessentialaminoacidsEssentialaminoacids(PVT.TIM.HALL):Phenylalanine,valine,threonine,tryptophan,isoleucine,methionine,histidine,arginine,lysine,leucine.Amongthese,arginineandhistidinearesemiessentialaminoacids.Nonessentialaminoacids:alanine,asparticacid,aspargine,cysteine,glutamine,glutamicacid,glycine,proline,tyrosine,serine.Neutralaminoacids:Alanine,asparagine,cysteine,glycine,glutamine,isoleucine,leucine,methionine,proline,phenylalanine,serine,threonine,tyrosine,tryptophan,valine.Acidicaminoacids(negativelychargedoranion):Asparticacid(aspartate),glutamicacid(glutamate).Basicaminoacids(positivelychargedorcation):Arginine,histidine,lysine.
436.Aminoacidwhichcanbeusedinboth gluconeogenesisandketogenesis- a)Threonine b)Valine c)Tyrosine d)Arginine CorrectAnswer-CAns.is'c'i.e.,Tyrosine[RefChatterjee5''/ep.448]Aminoacidswhichcanbeusedbothingluconeogenesisandketogenesis(Bothglucogenic&ketogenicaminoacids)are:- 1. Tyrosine2. Phenylalanine3. Tryptophan4. Isoleucine.
437.Inphenylketonuria,dietrestrictionis advisedfor- a)Tyrosine b)Phenylalanine c)Maize d)All CorrectAnswer-BAns.is'b'i.e.,Phenylalanine,Themaintreatmentisaphenylalaninerestricteddietforlife.
438.Guanidiniumgroupisassociatedwith- a)Tyrosine b)Arginine c)Histidine d)Lysine CorrectAnswer-BSomeaminoacidscontainaspecialfunctionalgroupintheirsidechainwhichprovidessomespecificfunctionstothataminoacids.Theseare 1. Hydroxylgroupinserineandthreonine2. Indoleringintryptophan3. Amidegroupinaspargineandglutamine4. 13-Carboxylinglutamicacid5. Thioetherinmethionine6. Imidazoleinhistidine7. Sulfhydrylincysteine8. Phenolintyrosine9. y-carboxylinglutamicacid 10. Pyrrolidineinproline11. Guanidiniuminarginine12. c-aminoinlysine13. Benzeneinphenylalanine
439.Coenzymeforphenylalaninehydroxylase is- a)Tetrahydrofolate b)Pyridoxalphosphate c)S-adenosylmethionine d)Tetrahydrobiopterin CorrectAnswer-DAns.is'd'i.e.,TetrahydrobiopterinPhenylalaninemetabolismisinitiatedbyitsoxidationtotyrosinewhichthenundergoesoxidativedegradation
440.Whichofthefollowingisrequiredinthe synthesisofacetylcholine- a)Inositol b)Carnitine c)Glycine d)Choline CorrectAnswer-DAns.is'd'i.e.,Choline[RefPrinciplesofmedicalphysiologyp.96]Acetylcholineissynthesizedinthecytosolofnerveterminalfromacetyl-CoAandcholine,inthepresenceofcholine-0-acetyltransferase
441.Mostimportantfactorwhichcauses lacticacidosisinalcoholics- a)PruductionofNADH b)Formationofacetaldehyde c)Productionofacetate d)Noneoftheabove CorrectAnswer-AAns.is'a'i.e.,ProductionofNADH[RefPankajNaik3rd/ep.351]ExcessintakeofalcoholleadstoexcessiveproductionofNADHwithaconcomitantdecreaseinNAD..TheincreasedavailabilityofNADHfavoursthereductionofpyruvatetolactateandoxaloacetatetomalateanddecreasingitsavailabilityforgluconeogenesisanddecreasesynthesisofglucose.ThisresultsinHypoglycemia.Excessoflactateproductionleadstolacticacidosis
442.Insulindependantcellsare- a)Pituitocytes b)Myocytes c)Adipocytes d)RBCs CorrectAnswer-B:CAns.is'b'i.e.,Myocytes&'c'i.e.,Adipocytes[RefGanong24th/ep.435]Insulinstimulatestheuptakeofglucosebymyocytes(skeletalmuscle,cardiacmuscle),adipocytes(adiposetissue)andhepatocytes.Tissuesthatdonotdependoninsulinforglucoseuptakeincludebrain,erythrocytes(RBC),theepithelialcellsofkidney&intestine,Liver,andCornea&lensoftheeye.Intheliver,insulinstimulatesglucoseentryintohepatocytesindirectlybyinductionofglucokinasesothattheglucoseenteringthelivercellsispromptlyconvertedtoglucose-6-phosphate(glucosetrapping).Thiskeepstheintracellularglucoseconcentrationlowandfavoursentryofglucoseintotheliver.Thus,thoughtheliverdonotdependoninsulinforglucoseuptake,insulinstimulatesglucoseentryintohepatocytes.Thatmeansglucoseentrycanoccurinliverwithouttheactionofinsulin,butthisisfacilitatedbyinsulin.Ontheotherhand,myocytes(skeletalandcardiacmuscles)andadipocytes(adiposetissue)aredependentoninsulinforglucoseuptake.
443.Epinephrineincreasesfreefattyacid levelbycausing- a)Increasedfattyacidsynthesis b)Increasinglipolysis c)Increasingcholesterolcatabolism d)Alloftheabove CorrectAnswer-BAns.is'b'i.e.,Increasinglipolysis[RefPankajNaik%talep.248]Epinephrineandglucagonacceleratelipolysisinadiposetissuebyactivatinghormonesensitivelipase.Instarvationanddiabetes,glucagonishigh(andinsulinislow),leadingtoenhancedlipolysis.
444.Vitaminformedinthebody- a)B1 b)B3 c)B6 d)B12 CorrectAnswer-A:B:DAns.is'b>a&d'i.e.,B3>B1&B12Thisquestionisconfusingone(Readtextbelow).Niacin(VitaminB3)issynthesizedfromtryptophaninsidethebody(endogenous).Somevitaminsarealsoformedbybacterialactivityincolon:- 1. VitaminK2. Riboflavin(VitaminB2)3. VitaminB124. Biotin(VitaminB7)5. Thiamin(VitaminB1) Thus,optionsa,b&dallarecorrecthere.Butthebestansweramongtheseisniacinasitistheonlyvitaminwhichissynthesizedbyproperanabolicmetabolism.
445.Whichofthefollowingisnotseenin12 daysoffasting- a)Gluconeogenesis b)Ketogenesis c)Lipolysis d)Glycolysis CorrectAnswer-DAns.isi.d.e.,Glycolysis[RefHarper28'Vep.140;Dineshpurl3'/ep.414] Intermediate Latestate{>24 Duration Earlystage stage(3-24d) d} Ketonebody Glycogenolysis oxidationBybrain Gluconeogenesis Gluconeogenesis Lipolysis Pathways Lipolysis Byothertissues Ketogenesis enhanced Ketogenesis Fattyacid Ketonebody Protein utilization oxidation degradation GluconeogenesisGlycolysisTCA Protein Pathways Proteinsynthesis degradation slowed anddegradation Proteinsynthesis Glycogensynthesis anddegradation
446.Pyridoxineisrequiredin- a)Glycolysis b)TCAcycle c)Glycogenesis d)Glycogenolysis CorrectAnswer-DAns.is'd'i.e.,Glycogenolysis[RefDineshpurip.187;Harper29th/ep.180&27th/ep.159-160]PLPisacofactorforglycogenphosphorylase,henceitfavorsglycogenolysis.
447.Pruritis[Itching]iscausedbydeficiency of- a)HMBsynthase b)5-ALAdehydratase c)Uroporphyrinogen-Isynthase d)Uroporphyrinogen-IIIsynthase CorrectAnswer-DAns.is'd'i.e.,Uroporphyrinogen-IIIsynthase[RefRooks7th/ep.12.7,12.8]Cutaneous(erythropoietic)porphyriascauseskinmanifestationslikephotosensitivity,rashandpruritus.Amongthegivenoptions,UroporphyrinegenIIIsynthasedeficiencycausescutaneousporphyria(Congenitalerythropoieticporphyria).
448.Vitaminactingonintranuclearreceptors - a)VitaminK b)VitaminD c)VitaminE d)VitaminE CorrectAnswer-BAns.is'b'i.e.,VitaminD[RefUnderstandingsmedicalphysiologyp.408]Twovitaminsareconsideredashormoneswhichactonintranuclearreceptors(steroidreceptorfamily).Thereare:- 1. VitaminA(retinoicacid)2. VitaminD
449.Niacinactsascoenzyme- a)TPP b)FAQ c)NAD d)NAD CorrectAnswer-CAns.is'c'i.e.,NADNiacin,intheformofnicotinamide,isincorporatedintothestructureoftwocoenzymes:nicotinamideadeninedinucleotide(NAD*)andnicotinamideadeninedinucleotidephosphate(NADI)*).
450.Notametabolicproductofureacycle- a)Citrulline b)Ornithine c)Alanine d)Arginine CorrectAnswer-CAns.is'c'i.e.,AlanineMetabolicproductsinureacyclearecarbamoylphosphate,ornithine,citrulline,argininosuccinate,arginineandfumarate.Biosynthesisofureaoccursinfivesteps1-Carbamoylphosphatesynthetase-I(CPS-I),amitochondrialenzyme,catalyzestheformationofcarbamoylphosphatebycondensationofCO,andammonia.2-Ornithinetranscarbamoylasecatalyzestheformationofcitrullinefromcarbamoylphosphateandornithine.3-Argininosuccinatesynthasecatalyzestheformationofargininosuccinatefromcitrullineandaspartate.Thisreactionrequires!ATP,4-Argininosuccinatelyase(arginosuccinase)catalysesthecleavageofargininosuccinateintoarginineandfumarate.FumarateentersTCAcycle.5-)Arginasecatalysestheformationofureafromargininebyhydrolyticcleavageofargininetoyieldureaandornithine.Ornithineisthusregeneratedandcanentermitochondriatoinitiateanotherroundoftheureacycle.
451.Whichaminoacidisnotinvolvedin transamination- a)Alanine b)Aspartate c)Lysine d)Histidine CorrectAnswer-CAns.is'c'i.e.,LysineMostaminoacidsundergotransaminationreactionexceptlysine,threonine,prolineandhydroxyproline.
452.ApoB48issynthesizedin- a)Liver b)Kidney c)Intestine d)RBCs CorrectAnswer-CAns.is'c'i.e.,IntestineItmediateuptakeofLDLbyLDLreceptorsofliver,
453.Whatareokazzakifragments- a)LongpiecesofDNAonlaggingstrand b)LongpiecesofDNAonleadingstrand c)ShortpiecesofDNAonlaggingstrand d)ShortpiecesofDNAonleadingstrand CorrectAnswer-CAns.is'c'i.e.,ShortpiecesofDNAonlaggingstrand[Ref:Lippincott's5thiep.399,401,406]DNApolymerasesresponsibleforcopyingtheDNAtemplatesareonlyableto"read"theparentalnucleotidesequencein3'-5'direction,andtheysynthesizethenewDNAstrandsonlyin5'-3'direction.Therefore,2newlysynthesizedchainsmustgrowinoppositedirections:? 1. TheDNAchainwhichrunsinthe3'45'directiontowardsreplication forkascontinuedstrandiscalledtheleadingstrand.ThisrequiresonlyoneRNAprimer 2. TheDNAchainwhichrunsinthe5'43'directionawayfromthe replicationforkiscalledlaggingstrand.ItissynthesizeddiscontinouslyandrequiresnumerousRNAprimers.Asthereplicationforkmoves,RNAprimersaresynthesizedatspecificintervals.TheseRNAprimersareextendedbyDNApolymeraseIIIintoshortpiecesofDNAcalledOkazakifragments.
454.C4,C5,N7inpurineringarederived from- a)Aspartate b)Glutamine c)Glutamine d)CO CorrectAnswer-CAns.is'c'i.e.,Glycine[RefHarper29th/ep.332]Indenovosynthesis,purineringisformedfromavarietyofprecursorsisassembledonribose-5-phosphate.Precursorsfordenovosynthesisare? 1. GlycineprovidesC4,C5andN72. AspartateprovidesNI3. GlutamineprovidesN3andN94. TetrahydrofolatederivativesfurnishC2andG5. CarbondioxideprovidesC6
455.IfcontentofAis15%,whatisthe amountofGinDNAaccordingtoChargaffsrule? a)15% b)85% c)35% d)70% CorrectAnswer-CAns.is'c'i.e.,35%[RefHarper'sIllustratedbiochemistry27th/ep.311-313]Chargaff'srule:Amountofpurine=Amountofpyrimidine(A+G=T+C)AlsoA+G+T+C=100SinceA=T,Therefore15+G+15+C=100SinceG=C,Therefore30,+2G=1002G=704G=35
456.cDNAfromRNAissynthesizedby- a)Helicase b)DNAdependentDNApolymerase c)Topoisomerase d)Reversetranscriptase CorrectAnswer-DAns.is'd'i.e.,Reversetranscriptase[RefSatyanarayan4th/ep.550]TheenzymeRNAdependentDNApolymerase(reversetranscriptase)isresponsiblefortheformationofDNAfromRNA.ThisDNAiscomplementary(cDNA)toviralRNAandcanbetransmittedintohostDNA.
457.Whichisnotachaperonprotein- a)Calnexin b)Proteindisulfideisomerase c)Calreticulin d)Calbindin CorrectAnswer-DAns.is'd'i.e.,Calbindin[RefHarper29thlep.598-599&28th/ep.497]SomeChaperonesandEnzymesInvolvedinFoldingthatareLocatedintheRoughEndoplasmicReticulum:-BiP(immunoglobulinheavychainbindingprotein)GRP94(glucose-regulatedprotein)CalnexinCalreticulinPDI(proteindisulfideisomerase)PPI(peptidylprolylcis-transisomerase)
458.Allarefunctionsofglycosaminglycans except- a)Lubrication b)Woundhealing c)Anticoagulant d)Transportoflipids CorrectAnswer-DAns.is'd'i.e.,Transportoflipids[RefPankajNaik4th/ep.29]
459.Bilesaltshelpinabsorptionoffatby- a)Micellesformation b)Activationoftransporterprotein c)Creationofconcentrationgradient d)Alloftheabove CorrectAnswer-AAns.is'a'i.e.,Micellesformation[RefGangong24thlep.465]Emulsificationistheprocesswhichbreaksdowningestedfats(mainlytriglycerides)intosmallerdropletssothattheycanbedigestedmoreefficiently.Thusemulsificationmainlyhelpsindigestionofingestedfats.Micellesformationistheprocessinwhichdigestedfats(FFAsandmonoglycerides)areincorporatedintomuchsmallerdroplets(micelles)sothattheycanbeabsorbedmoreefficiently.Thus,micellesformationhelpsinabsorptionofdigestedfats.Detergentactionofbilesaltsisnecessaryforbothemulsificationandmicellesformation.
460.a-aminolevulinicacidisametabolic productinsynthesisof- a)Tryptophan b)Collagen c)Glycosaminoglycans d)Heme CorrectAnswer-DAns.is'd'i.e.,HemeHemesynthesistakesplaceinallcells,butoccurstogreatestextentinbonemarrowandliver.ThefirststepinthesynthesisofhemeisthecondensationofglycineandsuccinylCo-Atoform6-aminolevulinicacid(6-ALA),whichoccursinmitochondria.Thisreactioniscatalyzedby6-ALAsynthasewhichrequirespyridoxalphosphate(PLP)ascofactor.Thisistheratelimitingstepinhemesynthesis.
461.Whichisaninhibitorofferrochelatase? a)Lead b)Mercury c)Iron d)Arsenic CorrectAnswer-AAns.is'a'i.e.,Lead[RefEssentialsofbiochemistry4thiep.919]Ferrochelatase,alsocalledhemesynthase,catalysesthelastreactioninhemesynthesis.LeadinhibitsALAdehydratase.Therefore,leadpoisoningcausesinhibitionofhemesynthesisandexcessiveamountof6-ALAisexcretedinurine.Leadcanalsoinhibitferrochelatase(hemesynthase).
462.Bileacidsconsistofallexcept- a)Lithocholicacid b)Taurocholicacid c)Deoxycholicacid d)Chendeoxycholicacid CorrectAnswer-BAns.is'b'i.e.,Taurocholicacid[RefGanong22nalech.26]Taurocholicacidisbilesalt(notbileacid).Bileacidsaremainlypresentsassodiumorpotassiumsaltswhichareconjugatedwithglycineortaurinetoformbilesalts.Primarybileacidsarecholicacidandchenodeoxycholicacid,whicharesynthesizedfromcholesterolinliver.Intheintestinesomeoftheprimarybileacidsareconvertedintosecondarybileacids,i.e.,deoxycholicacid(formedfromcholicacid)andlithocholicacid(derivedfromchenodexoxycholicacid).Glycineandtaurineconjugatesofthesebileacidsarecalledasbilesalts.Forexample,cholicacidisabileacid,anditsglycineconjugate(glycocholicacid)isabilesalt.
463.TrueaboutcAMPandcGMP- a)Secondmessengers b)Actonmembranereceptors c)Actbypost-translationalmodification d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,AlloftheaboveSecondmessengersSecondmessengersaremoleculesthatrelaysignalsfromthemembranereceptorstotargetmoleculesinsidethecells.InabovedescribedreceptorssecondmessengersarecAMP,cGMP,Phosphatidylinositol,diacylgleceral,IP3,Ca.Secondarymessengersofmembranereceptorsactbyposttranslationmodification,i.e.,modificationofproteins(e.g.,enzymes)aftertheyhavealreadyformed(i.e.,aftertranslation).
464.Spectroscopyisusedforinteractionof- a)Electromagneticradiation b)Protons c)Alphaparticles d)Positrons CorrectAnswer-AAns.is'a'i.e.,ElectromagneticradiationSpectroscopyisthestudyofthestructureofatoms/moleculesfromstudyingtheirinteractionwithelectromagneticradiation.
465.Abnormalproteinswhichareboundto ubiquitinaredegradedin- a)Proteosomes b)Golgiapparatus c)SmoothER d)Lysosomes CorrectAnswer-AAns.is'a'i.e.,Proteosomes[RefHarper250/ep.560-561&28th/ep.498-99]Ubiquitinplaysmajorroleindegradationofproteinsandisparticularlyassociatedwithdisposalofmisfoldedproteins.Itissmall,highlyconservedproteinthatplaysakeyroleinmarkingvariousproteinsforsubsequentdegradationinproteosomes
466.Enzymedegradationiscausedby- a)Ubiquitin b)RNAse c)Zymase d)Chaperone CorrectAnswer-AAns.is'a'i.e.,Ubiquitin[RefHarper29thiep.560-561]Degradationofdefective(misfolded)proteins(includingenzymes)iscausedbyubiquitin
467.G1cNAc-P-P-oligosacharrideis- a)Proteoglycan b)Glycoprotein c)Collagen d)Phospholipid CorrectAnswer-BAns.is'b'i.e.,Glycoprotein[RefMedicalBiochemistrybyBhagvanp.312]Dolicholplaysaroleinpost-translationalmodificationofproteinbyglycosylationtoformglycoproteins.ItactsintheformofDolicholpyrophosphate(DolicholPP)andtransferOligosaccharidefromdolicholtoglycoproteinsN-acetylgalactosamine-P-P-Dolichol(GLcNAc-P-P-dol)compoundformedinthebionsynthesisoflipid-linkedoligosaccharides.Dolichol-P-Pactsasacarrierofoligosaccharideandtransferittoglycoprotein.
468.Prolylhydroxylaserequirewhich cofactor- a)Sc b)VitaminC c)Mo d)VitaminK CorrectAnswer-BAns.is'b'i.e.,VitaminC[RefHarper29'Vep.590-593]Hydroxylationofprolineandlysineresiduetakesplaceduringpost-translationalmodificationinroughER.Theenzymecatalyzingthereactionsareprolylhydroxylase(forproline)andlysylhydroxylase(forlysine).Boththeseenzymesaredioxygenasesusingmolecularoxygen(02)andcofactorforboththeseenzymesisvitaminC(ascorbicacid).a-Ketoglutatrateisacoreductant,whichisoxidizedtosuccinate.
469.Sidechainlinkageinproteoglycons- a)Covalent b)Hydrogenbond c)Electrostaticbond d)Van-derWaal'sforce CorrectAnswer-AAns.is'a'i.e.,Covalent[RefEssentialsofbiochemistryp.712]Amongthegivenoptionstwobondsareinvolvedinproteoglycanstructure: 1. Covalent-Inproteoglyconmonomer,i.e.betweencentralcore proteinandsidechainofrepeateddisaccharides 2. ElectrostaticInproteoglycanaggregatesbetweenproteoglycan monomerandhyaluronicacid.
470.Whichoffollowingisnotafreeradical- a)H202 b)(M? c)Superoxideanion d)HOC1- CorrectAnswer-DAns.is'd'i.e.,HOC1?[RefPrinciplesinmedicalpathologyp.391]Freeradicalsarechemicalspeciesthathaveasingleunpairedelectronintheouterorbit.Mostofthesearepartiallyreducedreactiveoxygenformsthatareproducedasanunavoidablebyproductofmitochondria!respiration-alsoknownasreactiveoxygenspecies.Themostimportantarehydrogenperoxide(1120),Superoxideanion(02)andhydroxylradical(OH).
471.Intypelamaplesyrupurinedisease, genemutationseenis? a)Ela b)Elb c)E2 d)E3 CorrectAnswer-AAns.is'a'i.e.,Ela[RefHarper27"/ech.29;Nelson18th/ech.85.6;Medicalbiochemistrybysheriff1"/ep.513]Metabolicdisordersofbranched-chainaminoacidcatabolismAsthenameimplies,theodorofurineinmaplesyrupurinedisease(branched-chainketonuria)suggestsmaplesyruporburntsugar.Decarboxylationofleucine,isoleucine,andvalineisaccomplishedbyacomplexenzymesystem(branched-chaina-ketoaciddehydrogenase)usingthiaminepyrophosphate(vitamin81)asaconzyme.Thismitochondrialenzymeconsistsoffoursubunits:Ha,El(3,E2,andE3.DeficiencyofthisenzymesystemcausesMSUD.Basedonclinicalfindingsandresponsetothiamineadministration,fivephenotypesMSUDhavebeenidentifiedclassical,intermediate,intermittent,thiamineresponsiveandE3deficiency.AllformsofMSUDareinheritedasanautosomalrecessivetrait.
472.Hexokinaseisinhibitedby? a)Glucose-6-phosphate b)Glucagon c)Glucose d)Insulin CorrectAnswer-AAns.is'a'i.e.,Glucose-6-phosphate[Ref:Harper29"/ep.171,190]
473.Allofthefollowingareinhibitedduring fasting/starvation,except? a)Hexokinase b)Glucokinase c)PDH d)Pyruvatekinase CorrectAnswer-AAns.is'a'i.e.,Hexokinase[RefHarper29th/ep.190]Hexokinase(incontrasttoglycokinase)isnotaffectedbyfeeding/insulinorstarvation.Otherthreeenzymesactivityisdecreasedinstarvation.
474.HereditaryoroticaciduriaType-Iisdue todeficiencyof? a)Orotatephosphoribosyltransferase b)Oroticaciddecarboxylase c)UMPsynthase d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,Alloftheabove[RefPankajNaikp.310]Oroticaciduriaisahereditarydisorderwhichcanresultfromadefectiveenzymeinpyrimidinesynthesis.ThereisadefectinthemultifunctionalenzymeUMPsynthasewhichhastwoactivities:? 1. Orotatephosphoribosyltransferase2. Oroticaciddecarboxylase(orotidylatedecarboxylase) UMPsynthaseconvertsoroticacidtoUMP.Thus,indefectofUMPsynthaseoroticacidcannotbeconvertedtoUMPandisexcretedinurineoroticaciduria.Therearetwotypesoforoticaciduria. 1. TypeI:-ThereisdeficiencyofboththecomponentsofUMP synthase,i.e.orotatephosphoribosyltransferaseandoritidylatedecarboxylase. 2. TypeII:-Thereisdeficiencyofonlyorotidylatedecarboxylase/
475.ReplicationofmitochondrialDNAis causedbywhichtypeofDNApolymerase? a)a b)p c)S d)y CorrectAnswer-DAns.is'd'i.e.,y[RefPankajNaikp.314]DNApolymerasea:-Ithasprimaseactivity(i.e.synthesizesRNAprimer),andinitiatesDNAsynthesDNApolymerase:-ItisaDNArepairenzyme?DNApolymerasey:-ReplicatesmitochondrialDNADNApolymerase6:-HelpsDNAsynthesisonlaggingstrand,i.e.elongationofokazakifragmentsonlaggingstrand.Italsohas5'3'exonucleaseactivityforproofreading.DNApolymerasec:-HelpsinDNAsynthesisonleadingstrand.Italsohas5'->3'exonucleaseactivityforproofreading.
476.WhichisoformofLDHisraisedin Anemia? a)LDH5 b)LDH4 c)LDH3 d)LDH2 CorrectAnswer-DAns.is'd'i.e.,LDH2[RefChatterjea7th/ep.600-605,Harper28th/ep.59]LDH-2isfoundinRBCsandisincreasedinmegaloblasticanemia.
477.Digestiveenzymesare a)Hydrolases b)Oxidoreductases c)Dehydrogenases d)Ligases CorrectAnswer-AAns.is'a'i.e.,Hydrolases[RefHarper's29thlep.518-19]Alldigestiveenzymesarehydrolases.
478.Enzymesthatmoveamoleculargroup fromonemoleculetoanotherareknownas- a)Ligases b)Oxido-reductases c)Transferases d)Dipeptidases CorrectAnswer-CAns.isC.i.e.,Transferase[RefChatterjea8th/ep.123;Harper28th/ep.52]TransferasesCatalyzetransferofC-N-,orP-containinggroupfromonesubstratetoanother,
479.Glucose-6-phosphatedehydrogenase need- a)NAD b)NADP c)FAD d)FMN CorrectAnswer-BAns.is'b'i.e.,NADP[Ref:Harper29th/ep.197]NAD*-linkeddehydrogenasesPyruvatedehydrogenase,isocitratedehydrogenase,malatedehydrogenase,a-ketoglutaratedehydrogenase,glutamatedehydrogenase,glyceraldehyde-3-Pdehydrogenase,lactatedehydrogenase,p-hydroxyacylCoAdehydrogenase,glycerol3-Pdehydrogenase(cytoplasmic).NADP'-linkeddehydrogenasesGlucose-6-Pdehydrogenase,6-Phosphogluconatedehydrogenase,3-ketoacylreductase,Enoylreductase,gulonatedehydrogenase.FAD-linkeddehydrogenasesSuccinatedehydrogenase,fattyacylCoAdehydrogenase,glycerol-3Pet*hydrogenase(mitochondrial).
480.WhichofthefollowingisNADPlinked a)G6PD b)APDH c)a-ketoglutaratedehydrogenaes d)None CorrectAnswer-AAns.is'a'i.e.,G6PD[RefHarper28"lep.175]Amongstthegivenoptions,onlyG6-PD(glucose-6-phosphatedehydrogenase)isNADPlinkedenzyme.
481.Oxidativedeaminationoccursin? a)Cytoplasmofallcells b)Mitochondriaofallcells c)Cytoplasmofhepatocytes d)Mitochondriaofhepatocytes CorrectAnswer-DAns.is'd'i.e.,MitochondriaofHepatocytes[Ref:Harper29'/ep.274]Deaminationmeansremovalofaminogroupofaminoacidintheformofammonia.Thus,anaminoacidisconvertedtoaketoacid.Deaminationcoupledwithoxidationiscalledoxidativedeamination.Itoccursinthemitochondria.Oxidativedeaminationoccursprimarilyintheliver(majororgan)andkidney.
482.AldehydedehydrogenaserequiresNAD as? a)Cofactor b)Apoenzyme c)Coenzyme d)None CorrectAnswer-CAns.isC.i.e.,Coenzyme[RefReadbelow]Thecompleteenzyme,i.e.proteinpart(apoenzyme)withitsnon-proteinpartiscalledHoloenzyme.Alcoholdehydrogenaseistheenzyme(protein)partofcompleteenzyme(Holoenzyme).Thus,alcoholdedydrogenaseitselfisapoenzyme.Itrequiresnon-proteinpartNAD,whichisanorganiccomponent.So,NADactsascoenzymeforalcoholdehydrogenase.
483.InFITCthecoloremittedafterbluelight absorption?\ a)Yellowgreen b)Orangered c)Applegreen d)Goldenbrown CorrectAnswer-AAns.is'a'i.e.,YellowgreenFluoresceinisothiocyanate(FITC)isaderivativeoffluoresceinusedinwide-rangingapplicationsincludingflowcytometry.FITCistheoriginalfluoresceinmoleculefunctionalizedwithanisothiocyanatereactivegroup(-N=C=S),replacingahydrogenatomonthebottomringofthestructure.Thisderivativeisreactivetowardsnucleophilesincludingamineandsulfhydrylgroupsonproteins.FITC(fluoresceinisothiocyanate)isafluorochromedyethatabsorbsultravioletorbluelightcausingmoleculestobecomeexcitedandemitavisibleyellowgreenlight.Thisemissionceasesuponremovalofthelightcausingtheexcitation.
484.Apoenzymeis? a)Cofactor b)Coenzyme c)Proteinmoiety d)None CorrectAnswer-CAns.is'c'i.e.,Proteinmoiety[RefHarper2815/ep.52]Thecompleteenzyme(Holoenzyme)ismadeofproteinportion(apoenzyme)andcofactor/coenzyme.
485.Inxanthineoxidasecofactoris? a)Selenium b)Zn c)Molybdenum d)Mg CorrectAnswer-CAns.is'c'i.e.,Molybdenum[Ref:Essentialbiochemistryp.786]Twoimportantenzymesusingmolybdenumarexanthineoxidaseandsulfiteoxidase.
486.Whatareisoenzyme- a)Physicallysameformsofdifferentenzymes b)Physicallydisinctformsofsameenzyme c)Formsofsameenzymethatcatalyzedifferentreactions d)Formsofdifferentenzymethatcatalyzesamereactions CorrectAnswer-BAns.is'b'i.e.,PhysicallydisinctformsofsameenzymeIsoenzymesarethephysicallydistinceformsofthesameenzyme.Theycatalyzethesamechemicalreactionorreactionsbutdifferfromeachotherstructurally?,electrophoretically?andimmunologically.Isoenzymespossessquaternarystructure,andaremadeupoftwoorthreedifferentsubunit?(multimericQ).Thesubunitshaveslightlydifferentprimarystructures.Isoenzymescatalyzethesamereactionandactonsamesubstrate?,butwithdifferentKm?andVmaxvalues,i.e.,isozymeshavedifferentkinetics?.Theisoenzymescanbeseparatedfromeachotherbyelectrophoretic,chromatographicorimmunochemicaltechniques.Separationandquantitationofisoenzymescangiveinformationofgreatdiagnosticimportanceasthetissuedistributionofisoenzymesisquitespecific
487.Enzymecausingcovalentbondcleavage withouthydrolysis? a)Lyase b)Ligase c)Hydrolase d)Transferase CorrectAnswer-AAns.is'a'i.e.,Lyase[RefClassificationofenzymesfromyournotes]Cleavagebyhydrolysis(additionofwater)HydrolasesCleavagewithouthydrolysis(withoutadditionofwater)Lyases
488.Enzymesactby? a)Increaseinactivationenergy b)Decreaseinactivationenergy c)Shiftequilbriumconstant d)None CorrectAnswer-BAns.is'b'i.e.,DecreaseinactivationenergyInachemicalreaction,thesubstratehastobeconvertedtoahigherenergyform(calledtransitionform)beforeitcanformthereactionproducts.Thetransitionstateisstructurallyanintermediatebetweenthesubstrateandtheproduct,andrepresentsthehighestenergyarrangementofatoms.Therefore,itisunstable;onceformed,itdecomposesalmostimmediatelytoformthereactionproduct.So,thishighenergyintermediateactsasenergybarrier,separatingthesubstratesandtheproducts.Thisbarrier,calledthefreeenergyofaction,istheenergydifferencebetweentheenergyofthesubstratesandhighenergyintermediates.Inotherwords,initiallysomeenergymustbeputintothesubstrateforconversionintotransitionstate(high-energyintermediate);thisisthefreeenergyofactivation.Theenzymesspeedupthechemicalreactionbyloweringthemagnitudeoftheactivationenergybarrier,i.e.,freeenergyofactivation.
489.Shortestpeptide? a)AngiotensinII b)AngiotensinIII c)Oxytocin d)Vasopressin CorrectAnswer-BAns.is'b'i.e.,AngiotensinIII[RefEssentialsofbiochemistryp.627]
490.ThepredominantisoenzymeofLDH occuringinliverinjuryis? a)LDH-1 b)LDH-2 c)LDH-4 d)LDH-5 CorrectAnswer-DAns.is'd'i.e.,LDH-5[Ref:Essentialsofbiochemistryp.756]PredominantforminliverisLDH5.
491.Specificactivityofenzymeis? a)limo'ofenzymepergramofsubstrate b)Enzymeunitspermgofprotein c)Conc.ofsubstratetransformedperminute d)None CorrectAnswer-BAns.is'b'i.e.,Enzymeunitspermgofprotein[RefLippincott's3"1/ep.
492.Typeofinhibitionofaconitaseby Transaconitateis? a)Non-competitive b)Competitive c)Allosteric d)None CorrectAnswer-BAns.is'b'i.e.,Competitive[RefEssentialsofBiochemistryp.685] enzymes competitiveinhibitors 1 Lactatedehydrogenase Oxamate 2 Aconitase Transaconitate 3 Succinate MalanateQ dehydrogenase 4 HMG-CoAreductase HMG,Lovastatin 5 Dihydrofolatereductase Amethopterin,Methotrexate 6 Xanthineoxidase Allopurinol 7 Alcoholdehydrogenase Ethanol 8 Carbonicanhydrase Acetazolamide 9 Digoxin Na-KATPase 10 5-Fluorouracil Thymidylatesynthase
493.Functionalplasmaenzymeis? a)Fibrinogen b)LDH c)SGOT d)SGPT CorrectAnswer-AAns.is'a'i.e.,Fibrinogen[Refharper's28th/ep.59]Clotingfactors(includingfibrinogen)arefunctionalplasmaenzymes.
494.NADPHviaglycerophosphateshunt makeshowmanyATP? a)1 b)2 c)3 d)4 CorrectAnswer-BAns.is>b'i.e.,2[Ref:Harper29"/ep.129-130]Inglycerophosphateshuttle,themitochondrialenzymeislinkedtorespiratorychain(ETC)viaaflavoprotein,Soonly1.5molofATPareproduced(Accordingtooldercalculations,2ATPmolofATPareproduced).Inmalateshuttle,themitochondrialenzymeislinkedtoETCviaNAD,so2.5molofATPareproduced(accordingtooldercalculations3molofATPareproduced).
495.Whichofthefollowingtripeptide? a)Glutathione b)Angiotensin c)Glucagon d)Oxytocin CorrectAnswer-AAns.is'a'i.e.,Glutathione[RefHarper28thlep.679-680] AngiotensinIII Heptapeptide(6aminoacids)AngiotensinII Octapeptide(8aminoacids)Oxytocin Nonapeptide(9aminoacids) Bradykinin Nonapeptide(9aminoacids) Vasopressin Nonapeptide(9aminoacids)Glucagon Decapeptide(10aminoacids) AngiotensinI Decapeptide(10aminoacids)
496.Enzymeinvolvedinoxidative phosphorylation? a)Pyruvatekinase b)SuccinylCoAthiokinase c)NADHdehydrogenase d)None CorrectAnswer-CAns.is'c'i.e.,NADHdehydrogenase[RefHarper29'/ep.126-128,Vasudevan6thlep.234]Oxidativephosphorylationtakesphasealongtheelectrontransportchain(respiratorychain),wheretheATPissynthesizedindirectlyfromcreationofaproteingradientandmovementofprotiensacrossinnermitochondrialmembranehelpsinformationofATP.TheproteingradientiscreatedbylargechangeinfreeenergyduetotransportofelectroninETC.ElectronsentertheETCviaNAD'orFAD.ComplexI(NADH-CoQreductase)catalyzesthetransferofelectronfromNADHtocoenzymeQ(CoQ).{NADH-CoQreductaseisalsocalledNADHdehydrogenase.}.
497.Proteinsegregationoccursin? a)Golgiappparatus b)Peroxisomes c)ER d)Mitochondria CorrectAnswer-AAns.is'a'i.e.,Golgiappparatus[RefHarper29th/ep.549]Golgiapparatusplaysamajorroleinsortingofproteins.
498.Weakestbondis? a)Covalent b)Hydrogen c)Electrostatic d)Vanderwall CorrectAnswer-DAns.is'd'i.e.,Vanderwall[Ref:Harper28thlep.9;Basicsofmolecularbiologyp.786]StrongestbondCovalentWeakestbond-4VanderwallsforcesCovalent(strongest)?>Electrostatic0(ionicorsaltlinkage)>hydrogen>hydrophobic>Vanderwaal's(weakest)?
499.InETCNADHgenerates- a)1ATPs b)2ATPs c)3ATPs d)4ATPs CorrectAnswer-CAns.is'>c'i.e.,3ATPs[Ref:Harper28'"/ep.106,Vasudevan5thiep.231]TheenergyliberatedofsiteI(complexI)isusedtosynthesize1ATPmolecule,atsiteII(complexIII)isusedtosynthesize1ATPmoleculeandatsiteIII(ComplexIV)isusedtosynthesize1/2ATPmolecule.Thus,when1NADHmoleculeenterstherespiratorychain,itproduce2.5moleculesofATP?.WhenImoleculeofFADH2enterstherespiratorychainonly1.5moleculesofATPareproduced?assiteIofenergyliberationisbypassed.Note:PreviouslyitwasassumedtheNADHproduces3ATPsandFADgenerates2ATPs.Recentexperimentsshow-thattheseoldvaluesareoverestimatesandNADHproduces2.5ATPs?andFADH2produces1.5ATPs?.
500.Thisattachestoproteinbefore destruction? a)Ubiquitin b)RNAseF c)Zymase d)Chaperone CorrectAnswer-AAns.is'a'i.e.,Ubiquitin[RefHarper291Vep.560-561]UbiquitinIsaKeyMoleculeinProteinDegradationTherearetwomajorpathwaysofproteindegradationineukaryotes.OneinvolveslysosomalproteasesanddoesnotrequireATP.TheotherpathwayinvolvesubiquitinandisATP-dependent.Itplaysthemajorroleinthedegradationofproteins,andisparticularlyassociatedwithdisposalofmisfoldedproteinsandregulatoryenzymesthathaveshorthalf-lives.
501.Inglycolysis,inorganicphosphateis usedreaction,catalyzedby? a)Enolase b)Pyruvatekinase c)Glyceraldehyde-3-pdehydrogenase d)Aldolase CorrectAnswer-CAns.is'c'i.e.,Glyceraldehyde-3-pdehydrogenase[RefHarper's250/ep.171]
502.Proteinglycosylationoccursin? a)ER b)Golgibodies c)Mitochondria d)Peroxisomes CorrectAnswer-A:BAns.is'b>a'i.e.,Golgibodies>ER[RefHarper's29th/ep.549,572]TheendoplasmicreticulumandtheGolgiapparatusarethemajorsitesinvolvedinglycosylationprocesses.However,0-glycosylationoccursonlyintheGolgiapparatusandsoitistheorganellewherealltypesofglycosylationreactionscantakeplace
503.Trueaboutglycolysis? a)HexokinaseproduceATP b)1cycleproduces2ATP c)Itproducesdirectly2moleculesoflactate d)Aldolaseproducesirreversiblepolymerization CorrectAnswer-CAns.is'c'i.e.,Itproducesdirectly2moleculesoflactate[RefHarper29th/ep.170-177]Eachcycleofanaerobicglycolysisproduces2moleculesoflactate(lacticacid)whereasinaerobicconditionitproduces2moleculesofpyruvate.Optionbistrickyone.Eachglycolyticcycleproduces4ATPs(not2ATPs).Butoutofthese4ATPs,2areusedinthecycleitself.Therefore,thereisnetgainof2ATPs.So,:- 1. Eachcycleofglycolysisproduces-4ATPs.2. Eachcycleutilizes2ATPs3. Netgainineachcycle-2ATPs
504.Theratelimitingstepinglycolysisis catalyzedby? a)Pyruvatekinase b)Enolase c)Glucokinase d)Phosphofructokinase CorrectAnswer-A:C:DAns.is'd>a&c'i.e.,Phosphofructokinase>Pyruvatekinase&Glucokinase[RefLippincott's5thlep.99]Phosphofructokinase,glucokinaseandpyruvatekinaseareratelimitingenzymesofglycolysis.However,phosphofructokinaseisthemostimportantone.
505.Ratelimitingenzymeinhemesynthesis ? a)ALAsynthase b)Hmgcoareductase c)ALAdehydratase d)Uroporphyrinogen1synthase CorrectAnswer-AAns.is'a'i.e.,ALAsynthase[RefHarper's29'lep.309]Hemesynthesistakesplaceinallcells,butoccurstogreatestextentinbonemarrowandliver.ThefirststepinthesynthesisofhemeisthecondensationofglycineandsuccinylCo-Atoform6-aminolevulinicacid(6-ALA),whichoccursinmitochondria.Thisreactioniscatalyzedby6-ALAsynthasewhichrequirespyridoxalphosphate(PLP)ascofactor.Thisistheratelimitingstepinhemesynthesis.
506.Reversefoldingofproteinsiscarriedout by? a)Valine b)Threonine c)Chaperone d)Aspartate CorrectAnswer-CAns.is'c'i.e.,Chaperone[RefHarper's29th/ep.558,559]Certainproteinsplayaroleintheassemblyorproperfoldingofotherproteinswithoutthemselvesbeingcomponentsofthelatter.Suchproteinsarecalledmolecularchaperones.MostchaperonesexhibitATPaseactivityandbindADPandATP.Thisactivityisimportantfortheireffectonfolding
507.Myoglobincontains? a)Iron b)Copper c)Zink d)Selenium CorrectAnswer-AAns.is'a'i.e.,Iron[RefHarper29th/ep.308,Vasudevan6th/ep.242]Hemoproteinsareproteinswhichhavehemeasprostheticgroup.Importanthemoproteinsarehemoglobie,myoglobinQ,cytochromesQ(cytochromeCQ,cytochromeP450Q),catalaseQ,peroxidase,tryptophanpyrrolaseandnitricoxidesynthase.Allhemoproteinscontainironasironisthecentralcomponentofheme
508.Allareactivatedbyinsulinexcept? a)Lipoproteinlipase b)Pyruvatekinase c)Hormonesensitivelipase d)Acetyl-CoAcarboxylase CorrectAnswer-CAns.isC.i.e.,HormonesensitivelipaseEnzymes/PathwaysactivatedbyinsulinGlycolysis:PFK-1,Pyruvatekinase,glucokinase,PDH.Glycogenesis:Glycogensynthase.Lipogenesis:Acetyl-Co-carboxylase,Fattyacidsynthase.Cholesterolsynthesis:HMG-CoAreductase.Triglyceridesynthesis:Acyl-CoAglycerol-3-Ptransferase,glycerolkinase.Lipoproteindegradation:Lipoproteinlipase
509.Acuteintermittentporphyriaisdueto deficiencyof? a)UroporphyrinogenIsynthase b)UroporphyrinogenIIIsynthase c)Ferrochelatase d)ALAsynthase CorrectAnswer-AAns.is'a'i.e.,UroporphyrinogenIsynthase[RefHarper29tVep.313]
510.Nonsensecodonsbringabout? a)Elongationofpolypeptidechain b)Pre-translationalmodificastionofprotein c)Initiationofproteinsynthesis d)Terminationofproteinsynthesis CorrectAnswer-DAns.isD.i.e.,Terminationofproteinsynthesis[RefHarper28"lep.353,354]Stoporterminationornonsensecodons:-Threeofthe64possiblenucleotidetripletsUAAQ(amber0),UAGQ(Ochre)andUGAQ(opal)donotcodeforanyaminoacid.Theyarecallednonsensecodonsthatnormallysignalterminationofpolypeptidechains0.Thus,thoughthereare64possibletripletcodons,only61codesfor20aminoacids(asremainingthreearenon-sensecodons).
511.Repeatitivechainsofglucosaminewith uronicacidareseenin? a)NANA b)Heparansulphate c)Keratansulphate d)Noneofthese CorrectAnswer-BAns.is`b'i.e.,Heparansulphate[RefDineshpuriYalep.31,32]Proteoglycansaremadeupofcoreprotein,coretrisaccharideandglycosaminoglycans.Proteoglycans=Glycosaminoglycans+Coretrisaccharide+Coreprotein.Glycosaminoglycans(mucopolysaccharides)aremadeupofrepeatingdiasaccharideunits.Eachdiasaccharideunitcontains?
512.ATPisconsumedatwhichstepof glycolysis a)Enolase b)Hexokinase c)Pyruvatekinase d)Isomerase CorrectAnswer-BAns.is'b'i.e.,HexokinaseATPisconsumedatreactionscatalysedby-hexokinase,phosphofructokinaseI.ATPisproducedatreactionscatalyzedby->phosphoglyceratekinase,pyruvatekinase.
513.WhichofthefollowingGAGisnot sulphated? a)Chondroitin b)Dermatan c)Keratan d)Hyaluronicacid CorrectAnswer-DAns.is'd'i.e.,Hyaluronicacid[Ref:Harper's29thlep.596]AGlycosaminoglycan(GAG)isanunbranchedpolysaccharidemadeupofrepeatingdisaccharides,onecomponentofwhichisalwaysanaminosugar(hencethenameGAG),eitherD-glucosamineorD-galactosamine.Theothercomponentoftherepeatingdisaccharide(exceptinthecaseofkeratansulfate)isauronicacid,eitherL-glucuronicacid(GlcUA)orits5'-epimer,L-iduronicacid(IdUA).Proteoglycansareproteinsthatcontaincovalentlylinkedglycosaminoglycans.Theproteinsboundcovalentlytoglycosaminoglycansarecalled"coreproteins".Withtheexceptionofhyaluronicacid,alltheGAGscontainsulfategroups,eitheras0-estersorasN-sulfate(inheparinandheparansulfate).Hyaluronicacidaffordsanotherexceptionbecausethereisnoclearevidencethatitisattachedcovalentlytoprotein,asthedefinitionofaproteoglycangivenabovespecifies.
514.MethioninecanentretheTCAcycleat whichlevel? a)Fumarate b)Oxabacetate c)Succinyl-CoA d)Citrate CorrectAnswer-CAns.is'c'i.e.,Succinyl-CoA
515.RatelimitingstepsinTCAcycle? a)a?KetoglutarateSuccinylCoA b)Citrate-Isocitrate c)SuccinylCoA4Succinate d)Succinate-Fumarate CorrectAnswer-AAns.is'a'i.e.,alpha-Ketoglutarade-SuccinylCoA[RefHarper's28th/ep.147,154]RegulatingstepsinTCACyclearecatalyzedby:a)CitrateSynthase:CatalyzescondensationofacetylCoA&oxaloacetatetofromcitrate.Isocitratedehydrogenase:Catalyzestheconversionofisocitratetoa-ketoglutaratebydecarboxylation.a-ketoglutaratedehydrogenase:Catalyzestheconversionofa-ketoglutaratetosuccinylCoA
516.Thefoldsincollagenisdueto? a)Glycine b)Alanine c)Arginine d)Histidine CorrectAnswer-AAns.is'a'i.e.,Glycine[RefEssentialsofbiochemistyp.868]Inordertoformatriple-helixapolypeptidechain(a-chain)mustcontainglycineaseverythirdresidueinthesequence.Thisisbecauseonlytheglycineissmallenoughtobeaccommodatedinthelimitedspaceavailabledownthecentralcoreofthetriplehelix.Eachturnofpolypeptidechain(a-chain)containsthreeaminoacidresidues,andglycine(Gly)ispresentateverythirdpositions.Thusglycineconstitutes33%ofthetotalaminoacidresidues.Therepeatingaminoacidresidues,representedas(Gly-X-Y)n,isanabsoluterequirementforformationoftriplehelix.XandYcanbeanyaminoacids,butmostofthetimeXisproline(10%ofthetotalaminoacidresidues)andmostofthetimeYishydroxyproline.
517.RatelimitingstepinTCAcycleis catalyzedby- a)a-ketoglotaratesynthase b)Fumarase c)Aconitase d)Thiokinase CorrectAnswer-AAns.is'a'i.e.,a-ketoglotaratesynthase[RefHarper28th/ep.147,154]
518.Whichofthefollowingstatements regardingmaturecytoplasmicmessengerRNAistrue? a)TranscribedfromNuclearDNA b)HasThiamineinplaceofUracil c)SugarisDeoxyRibose d)Itsmolecularweightismorethanhn-RNA CorrectAnswer-AAns.is'a'i.e.,TranscribedfromNuclearDNA[Ref:Lippincott'sBiochemistry5thp.428;FundamentalsofCytogenetics&Genetics(2010)p.444]MesengerRNA(mRNA)isformedbytheprocessof'transcription'fromoneofthestrandsofdoublestrandednuclearDNAandcarriesgeneticinformationfromthenuclearDNAtothecytosolwhereitisusedasatemplateforproteinsynthesis.mRNAcomprisesonly5-10%oftotalcellularRNA.Itcarriestheinformation(massage)fromthenucleustotheribosome.mRNAissynthesizedinthenucleusaslieterogenousRNA(hnRNA)',whichisprocessedintofunctionalmRNA.
519.Fluroacetateinhibits? a)Citratesynthetase b)Aconitase c)Succinatedehydrogenase d)Alphaketoglutaratedehydrogenase CorrectAnswer-BAns.is'b'i.e.,Aconitase[RefHarper28thIep.145]
520.IdentificationofindividedbytheirDNA wasinventedby? a)Shapiro b)Lewis c)Jeffreys d)Pasture CorrectAnswer-CAns.is'c'i.e.,Jeffreys[RefLippicott'sSthiep.83,474,Lehniger5thiep.319-21]TheDNAfingerprintingwasfirstreportedin1984bySirAlecJeffreys?attheuniversityofleicesterinEngland.
521.Inhibitorsofglycolysisareallexcept? a)Fluoride b)Fluoroacetate c)Arsenite d)Iodoacetate CorrectAnswer-BAns.is'b'i.e.,Fluoroacetate[RefHarper's28`"/ep151]FluoroacetateisaninhibitorofTCAcycle.
522.Whichoffollowingisananalouge guanosine? a)Abacavir b)Allopurinol c)Bromodeoxyuridine d)None CorrectAnswer-AAns.is'a'i.e.,Abacavir[RefEssentialsofbiochemistryp.888]
523.DNAmicroarraysallowdetectionofGene mutationsusing? a)PolymerasechainReaction b)Cloning c)SouthernBlotting d)Hybridization CorrectAnswer-DAns.is'd'i.e.,Hybridization[RefBiologybyRavenTatap.331]DNAMicroarray(DNA-Chips)DNAmicroarrayscontainthusands(500-5000)ofimmobilizedDNAprobes/sequences(fewdozentohundredsofnucleotidelong)fromknowngenesorganizedinanareanolongerthanamicroscopeslide.DNAsegments(fromDNAlibraries)areamplifiedbyPCRandplacedonsmallwellsinasolidpolystyreneplates,usingroboticdevices.Uptomillionsuchspotsaredepositedinapredesignedarrayonasurfaceareaofjustfewcm'.AnalternatewayistosynthesizeDNAdirectlyonthesolidsurfaceusingphotolithography.C-DNA(obtaineddirectlyorfrommRNAofpatientsparticularcelltypeorstage)isaddedtoeachwell,hybridizeandfluorescenceisassessedtoassessgenesbeingexpressedinthosecells/stage.Thisisbasedonprinciplesofnucleicacidhybridizationlikesouthernornorthernblottestsbutallowssimultaneousstudyofmultiplegenesorentiregenomeratherthansingle.HybridizationmeansbindingofcomplementarystrandsofnucleicacidaccordingtoWatson-Crickrules(i.e.A=TandG=Cbinding).SouthernblotforDNAandNorthernblotforRNAallowsthestudy/detectionofsinglegenewhereasmicroarraytechnique(forDNA&RNA)allowsdetectionofmultiplegenesorentiregenome.
SoitcanbeconsideredasmultipleSouthernorNorthernblotanalysisrunninginparallel.
524.Thebiosynthesisoftheenzymepyruvate carboxylaseisrepressedby? a)Insulin b)Glucagon c)Cortisol d)Epinephrine CorrectAnswer-AAns.is'a'i.e.,Insulin[Ref:Harper28th/ep.168]Gluconeogenesisisregulatedbyfourkeyenzymes:(i)Pyruvatecarboxylase;(ii)Phosphoenolpyruvatecarboxykinase;(iii)Fructose-1,6-bisphosphatase;and(iv)Glucose-6-phosphatase.Thehormoneglucagon,epinephrineandglucocorticoidsstimulategluconeogenesis,byinducingtheseenzymes.Conversely,insulininhibitsgluconeogenesisbyrepressingtheirsynthesis.
525.Terminationcodonis? a)AUG b)UAA c)AUA d)AGG CorrectAnswer-BAns.is'b'i.e.,UAAInitiationcodon.4AUGStopcodons(terminationcodonsornonsensecodons)UAA,UGA,UAG
526.Wherecanglucose6phosphatenotbe convertedtoglucose? a)Muscle b)Liver c)Adiposetissue d)Kidney CorrectAnswer-AAns.is'a'i.e.,Muscle[Ref:Harper250lep.178-179]Glucose-6-phosphataseisabsentinmusclestherefore,glucose-6-phosphatecannotbedegradedtofreeglucoseinmuscles.Moreover,glucose-6-phosphatecannotdiffuseoutofthemuscles.Therefore,musclecannotprovideglucosetomaintainbloodglucoselevel.Rather,muscleglycogenactsasasourceofenergy;theglucose-6-phosphateenterstheglycolysistoproduceenergy.
527.Commonintermediatebetween gluconeogenesisandfattyacidsynthesis? a)Glucose-6-phosphate b)Acetyl-CoA c)Citrate d)Succinyl-CoA CorrectAnswer-CAns.is'c'i.e.,Citrate[RefHarper29thlep.188]CitrateinGluconeogenesisGluconeogenesisinvolvesglycolysis,thecitricacidcycleandsomespecialreactions.Citrateisanintermediarymetabolismofgluconeogenesis(throughTCAcycle).
528.Chromosomalstudyisbestcarriedout in? a)Prophase b)Metaphase c)Telophase d)Anaphase CorrectAnswer-BAns.is`b'i.e.,Metaphase[Ref:Anderson10thlep.225,226,Robbins8thiep.158]MethodofkaryotypingKaryotypingisthestudyofcoromosone.Dividingcellsarearrestedinmetaphasebyadditionofcolchicineorcolcemid(deacetylmethylcolchicine).Subsequently,cellsareexposedtoahypotonicsolutiontoinduceswellingofthecellforenhancingspreadingofthechromosomes.Themetaphasecellsarethenfixedwithmethanol/glacialaceticacidmixtureandstainedbyoneoftheseveralbandingtechniques.Afterstainingchromosomesareanalysedunderamicroscopeandphotographed.Finally,akaryotypeisconstructedbymanualorautomatedpattern.Chromosomesarearrangedinpairsanddecreasingorderoflength
529.Glycogensynthaseisactivatedby? a)Insulin b)Glucagon c)Epinophrine d)AMP CorrectAnswer-AAns.is'a'i.e.,Insulin[RefHarper28th/ep.159-161,Lehinger5th/ep.603,604]
530.Whichofthefollowingusuallyrequirea RNAintermediateforcloning/replication? a)Transposons b)Plasmids c)Phages d)Cosmids CorrectAnswer-AAns.is'a'i.e.,Transposons[Ref:Lippincot4th/ep.461&Harper29tVep.436,437]Transposons(Tn)aremobilesegmentsofDNAthatmoveinanessentiallyrandommannerfromonesitetoanotheronthesameoradifferentchromosome.Movementismediatedbytransposase,anenzymeencodedbyTnitself.Movementcanbe:-(i)direct,inwhichtransposasecutsoutandtheninsertsTnatanewsite,or(ii)replicative,inwhichtheTniscopiedandthecopyinsertedelsewherewhiletheoriginremainsinplace.Ineukaryotes,includinghumans,replicativetranspositionfrequentlyinvolvesaRNAintermediate,inwhichcasethetransposoniscalledaretrotransposoni.e.tronsposonsthatinvolveaRNAintermediatearecalledretrotransposons
531.Glycogenstoragediseasewhich presentsaslysosomalstoragedisease? a)Vongierke'sdisease b)Pompesdisease c)Mcardle'sdisease d)Andersen'sdisease CorrectAnswer-BAns.is'b'i.e.,Pompesdisease[RefLippincott's4th/ep.129-131]TypeIIglycogenstoragedisease(Pompesdisease)istheonlyglycogenstoragediseasethatisalysosomalstoragedisease
532.Insicklecellanemia,translocationon codon6isduetosubstitutionof? a)Valineforglutamate b)Glutamateforvaline c)Isoleucineforvaline d)Valineforisoleucine CorrectAnswer-AAns.is'a'i.e.,Valineforglutamate[RefHarper's29th/ep.444]Sicklecelldisease,iscausedbymutationofasinglebaseoutofthe3x109inthegenome,aT-to-ADNAsubstitution,whichinturnresultsinanA-to-UchangeinthemRNAcorrespondingtothesixthcodonofthe13-globingene.Thealteredcodonspecifiesadifferentaminoacid(valineratherthanglutamicacid),andthiscausesastructuralabnormalityofthep-globinmolecule.
533.Aldolase-Bisinvolvedinmetabolismof ? a)Galactose b)Fructose c)Sucrose d)None CorrectAnswer-BAns.is'b'i.e.,Fructose[RefHarper's28th/ep.179)
534.Inhumans,ascorbicacidcannotbe synthesizedbecauseof? a)DeficiencyofG6PD b)Deficiencyofxylulosekinase c)DeficiencyofL-gulonolactoneoxidase d)Deficiencyofphosphoglucomutase CorrectAnswer-CAns.is'c'i.e.,DeficiencyofL-gulonolactoneoxidaseInman,otherprimatesandguineapigs,ascorbicacidcanbesynthesizedduetoabsenceofL-glucanolactoneoxidase,anenzymeusedinloweranimalstosynthesiseascorbicacidasabyproductofuronicacidpathway(glucuronicacidcycle).
535.Functionofexonuclease- a)Polymerization b)Proofreading c)Chainelongation d)Termination CorrectAnswer-BAns.is'b'i.e.,Proofreading[RefDineshpuri3rd/ep.455,456]Nucleasesreferstoanenzymethatcatalyzeshydrolysisofphosphodiesterbondinanucleicacid.Thenuclesesareoftwotypes:*Endonucleases:Cleavetheinternalphosphodiesterbonds.*Exonucleases:Cleavebondsatends.Someexonucleasescleaveonlyatthe3'end(the3'-exonucleaseactivity)whileothercleaveatthe5'end(the5'-exonucleaseactivity).-31-exonucleaseactivityisresponsibleforproofreading.3'-exonucleaseactivityispresentinDNApolymeraseI,IIandIII.-51-exonucleaseactivityisresponsibleforerrorcorrectionindamagedDNA.
536.Glucoseoxidaseconvertsglucoseto? a)Gluconicacid b)Glucuronicacid c)Iduronicacid d)Galacticacid CorrectAnswer-AAns.is'a'i.e.,Gluconicacid[Ref:Internet]Oxidase-peroxidaseenzymesystemisusedtodetermineglucoseinurine&blood.Glucoseoxidaseenzymeproduceshydrogenperoxide&gluconicacidfromglucose.PeroxidasecatalysesthereactionofH202withcolourlesspotassiumiodidetobrowniodide.Thisproducesacolourchange,theintensityofwhichmayindicateglucoseconcentrationinsometests(suchasBoehringer,Diastix).
537.Glucoseisconvertedtoglucuronateby? a)Oxidationofaldehydegroup b)Oxidationofterminalalcohol c)Oxidationofboth d)None CorrectAnswer-BAns.is'b'i.e.,Oxidationofterminalalcohol[RefChatterjee8th/ep.29]Whenaldosesugarsareoxidizedtheymayformthreedifferentsugaracid,dependinguponoxidationofaldehydegroup(atC-1)orterminalalcoholgroup(atC-6). 1. Aldonicacid:-Oxidationofanaldosewithhypobromousacid (HOBr)oxidisesonlyaldehydegroupandconvertittocarboxylgrouptoformaldonicacid.Forexample,glucoseisoxidizedtogluconicacid. 2. Saccharicacid:-Oxidationofaldoseswithnitricacidconvertboth aldehydeandterminalprimaryalcoholgroupstocarboxylgroup,formicsaccharicacid.Forexample,glucoseisoxidizetoglucosaccharicacid. 3. Uronicacid:-Whenanaldoseisoxidizedinsuchawaythatthe terminalprimaryalcoholisconvertedistocarboxylwithoutoxidationofaldehydegroup,auronicacidisproduce.Forexample,glucoseisoxidizedtoglucuronicacid.
538.Enzymerequireforcuttingthestrand DNAsynthesis? a)DNApolymerase b)DNAligase c)Topoisomerase d)Helicase CorrectAnswer-CAns.is'c'i.e.,Topoisomerase[RefLippincott's5thiep.400,401]AsthetwostrandsofDNAareseparatedaproblemisencountered,i.e.appearanceofpositivesupercoils(supertwists)intheregionofDNAaheudofreplicationform.Theaccumulationofpositivesupercoilinginterfereswithfurtherunwindingofthedoublehelix.Tosolvethisproblem,thereisagroupofenzymescalledDNAtopoisomeraseswhichareresonsibleforremovingsupercoilsinthehelix.DNAtopoisomerasesarenickandsealenzymes,i.e.theyhavebothnuclease(strand-cutting)andligase(strand-resealing)activities.
539.Increaseduricacidlevelsareseenin whichglycogenstoragedisease? a)TypeI b)TypeII c)TypeIII d)TypeIV CorrectAnswer-AAns.is'a'i.e.,TypeI[RefHarper29m/ep.339]PurineoverproductionandhyperuricemiainvonGierkedisease(glucose-6-phosphatasedeficiency)occurssecondarytoenhancedgenerationofPRPPprecursor,i.e.ribose-5-phosphate(apentose).Inglucose-6-phosphatasedeficiency,glucose-6-phosphatecannotbeconvertedtoglucose.Accumulatedglucose-6-phosphateisthenmetabolizedviaHMPshunt,whichinturngenerateslargeamountsofribose-5-phosphate,aprecursorofPRPP.TheincreasedsynthesisofPRPPthenenhancesdenovosynthesisofpurinenucleotides
540.Gulonatedehydrogenaserequires? a)NADP b)NAD c)FAD d)FMN CorrectAnswer-AAns.is'a'i.e.,NADP[RepHarper29t5/ep.201-204]Gulonatedehydrogenaseisanenzymeinglucuronicacidpathway(uronicacidpathway)thatrequiresNADP'.
541.Reversetranscriptioninvolves? a)RNAdependentDNAsynthesis b)DNAdependentRNAsynthesis c)DNAdependentDNAsynthesis d)RNAdependentRNAsynthesis CorrectAnswer-AAns.is'a'i.e.,RNAdependentDNAsynthesis[RefHarper29thlep.348]SynthesisofRNAfromDNAiscalledtranscription.Intranscription,RNAissynthesizedbyRNApolymerase.RNApolymeraseisalsocalledDNAdependentRNApolymerasebecauseitisdependentonDNA(non-codingstrand)forRNAsynthesis.Reversetranscription,asthenamesuggests,isthereverseoftranscriptioni.e.synthesisofDNAformRNA.InreversetranscriptionDNAissynthesizedbyreversetranscriptase.ReversetranscriptaseisalsocalledRNAdependentDNApolymerasebecauseitisdependentonRNAforDNAsynthesis.
542.MutationinGLUT-2causes? a)Dandywalkersyndrome b)Fanconibeckersyndrome c)Beckwithsyndrome d)Menke'sdisease CorrectAnswer-BAns.is'b'i.e.,Fanconibeckersyndrome[RefDiagnosticofEndocrinefunctionischildrenandadolescentsp.271]GLUT2isexpressedinpancreatic13-cells,hepatocytesandinepithelialcellsofkidneyandintestine.Fanconi-BickelsyndromeiscausedbyGLUT2mutation,adiseasecharacterizedbyproximalrenaltubulopathy,impairedglucosehomeostasisandhepatomegaly.
543.Aminosugarareformedforms? a)Glucose-1-phosphate b)Glucose-6-phosphate c)Fructose-1-phosphate d)Fructose-6-phosphate CorrectAnswer-DAns.is'd'i.e.,Fructose-6-phosphate[RefDineshpuri3rdlep.170]Aminosugarsaredervativesofmonosaccharidesinwhichanaminogroupreplacesthe-OHresidueoncarbon-2ofhexose,suchasglucose,galactoseandmannose,Thecorrespondingcompoundsareglucosamine,galactosamineandmannosamine,respectively.Theaminoacidgroupisusuallyacetylated,e.g.N-acetylglucosamineorN-actylgalactosamine.Theaminosugarsarerequiredforthesynthesisofglycolipids,glycoproteinsandproteoglycans.Theyaresynthesizedfromfructose-6-phosphate
544.Differencebetweenganglioside& cerebroside,allexcept? a)Charge b)PresenceofNANA c)Presenceofcarbohydrate d)Nativetissue CorrectAnswer-CAns.is'c'i.e.,Presenceofcarbohydrate[RefLippincott's4th/ep.208-210]Bothgangliosideandcerebrosidecontaincarbohydrateasbothareglycolipids.NANAispresentinganglioside(notincerebroside).
545.Inglycolysis,NADHisproducedat? a)Pyruvatekinase b)Enolase c)Glyceraledehyde-3-P-dehydrogenase d)PFK-1 CorrectAnswer-CAns.is'c'i.e.,Glyceraledehyde-3-P-dehydrogenase[RefHarper28th/ep.151-152]Reducingequivalent(NADH)productioniscatalyzedby:Glyceraldehyde3-phosphatedehydrogenase
546.1"acetylgroupdonorinfattyacid synthesisis? a)MalonylCoA b)Palmitate c)AcetylCoA d)Citrate CorrectAnswer-CAns.is'c'i.e.,AcetylCoA[Ref:Harper29"lep.216-217]Acetyl-CoAactsasaprimertodonate1st2carbonatoms(C-15andC-16)ofpalmitate.TheadditionofallthesubsequentC2unitsisviamalonyl-CoA.Propionyl-CoAactsasprimer(fordonatingfirst3carbonatoms)inthesynthesisofodd-carbonnumberfattyacids.
547.Chargaff'srulestatesthat? a)A=T,G=C b)A=G,T=C c)A=C,G=T d)Anycombinationpossible CorrectAnswer-AAns.is'a'i.e.,A=T,G=C[Ref:Harper29th/ep.344&28thlep.302;Essentialsofbiochemistryp.915]ChargaffsrulestatesthatinDNAofallspeciesquantitiesofpurinesisthesameasthatofpyrimidines,i.e.A+G=T+C
548.Onlyvitaminthathelpincarbonfixation ? a)Folicacid b)Pantothenicacid c)Niacin d)Thiamine CorrectAnswer-AAns.is'a'i.e.,Folicacid
549.Ratecontrollingenzymeoffattyacid synthesis- a)Thioesterase b)Transacetylase c)Acetyl-CoAcarboxylase d)Ketacylsynthase CorrectAnswer-CAns.is'c'i.e.,Acetyl-CoAcarboxylase[RefHarper29th/ep.217,220]Productionofmalonyl-CoAistheinitial?andratelimitingstepinfattyacidsynthesis.Acetyl-CoAneedstobeconvertedtoactivatedform,whichwillserveasthedonorofcarbonunitstogrowingfattyacidchain.Malonyl-CoA?)a3-carboncompoundissuchactivatedform.Itisproducedbycarboxylationofacetyl-CoA,areactioncatalyzedbyacetyl-CoAcaroxylase?.Acetyl-CoAcarboxylaserequiresbiotinasacofactor?.
550.Primerfunctionisin? a)Transcription b)Translation c)InitiationofDNAreplication d)TerminationofDNAreplication CorrectAnswer-CAns.is'c'i.e.,InitiationofDNAreplication[RefHarper's29thlep.366,367]DNAsynthesiscannotcommencewithdeoxyribonucleotidesbecauseDNApolymerasecannotaddamononucleotidetoanothermononucleotide.Thus,DNApolymerasecannotinitiatesynthesisofcomplementaryDNAsynthesisstrandofDNAonatotallysinglestrandedtemplate.Forthis,theyrequireRNAprimer,whichisashortpieceofRNAformedbyenzymeprimase?(RNApolymerase?)usingDNAasatemplate.RNAprimeristhenextendedbyadditionofdeoxyribonucleotides.Lateron,theribonucleotidesoftheprimerarereplacedbydeoxyribonucleotides.
551.Whichofthefollowingisaribozyme? a)Peptidyltransferase b)Elongationfactor2 c)Primase d)RNApolymerase CorrectAnswer-AAns.is'a'i.e.,Peptidyltransferase[RefHarper29thIep.405]SomeRNAmoleculeshaveintrinsiccatalyticactivity.Theactivityoftheseribozymesofteninvolvesthecleavageofnucleicacid.TwoimportantRNAenzymesorribozymesare:?ThepeptidyltransferasethatcatalyzespeptidebondformationontheribosomeandRibozymesinvolvedintheRNAsplicing.
552.WhichRNAisusedinRNAsplicing? a)mRNA b)SmallnuclearRNA c)SmallcytosolicRNA d)tRNA CorrectAnswer-BAns.is'B'i.e.,SmallnuclearRNA[RefHarper29th/ep.378,390]SplicesomeSplicesomeisanassemblymadeupofsmallnuclearRNA(snRNA),someproteinsandhnRNA.snRNAcombineswithproteinstoformsmallnuclearribnonucleoproteinparticles(snRNPsorsnurps)thatmediatesplicing.ItissnRNAcomponentofsnurpsthatcatalyzessplicing?.SnurpsareU,,U,,U3,U4,U5andU6
553.Whatisattatchedto3'endofmRNAafter transcription? a)PolyAtail b)CCA c)Intron d)7-methylguanosine CorrectAnswer-AAns.is'a'i.e.,PolyAtail[Ref:Harper's29`h/ep.392]MammalianmRNAmoleculescontaina7-methylguanosinecapstructureattheir5'terminal,andmosthaveapoly(A)tailatthe3'terminal.ProkaryoticmRNAisfunctionalimmediatelyuponsynthesis,i.e.prokaryoticprimarytranscriptofmRNAisfunctional.Thusitdoesnotrequirepost-transcriptionalmodification.InEukaryotestheprimarytranscriptofmRNAisthehnRNA(hetrogeneousnuclearRNA).AftertranscriptionhnRNAisextensivelymodifiedtoformfunctionalmRNA.
554.Primasefunctionsas? a)JoiningDNAfragments b)SynthesiningsmallRNAfragmentsduringDNAsynthesis c)SynthesisingsmallRNAfragmentsduringtranslation d)UnwindingofDNA CorrectAnswer-BAns.is'b'i.e.,SynthesiningsmallRNAfragmentsduringDNAsynthesis[RefHarper's29th/ep.366,367]
555.WhatisthefunctionofDNAligase? a)Unwinding(denaturation)ofdsDNAtoprovideanssDNA template b)Sealsthesinglestrandnickbetweenthenascentchainand Okazakifragmentsonlaggingstrand c)InitiationofDNAsynthesisandelongation d)InitiatessynthesisofRNAprimers CorrectAnswer-BAns.is'b'i.e.,SealsthesinglestrandnickbetweenthenascentchainandOkazakifragmentsonlaggingstrand[RefHarper2501ep.367]
556.CentralDogmaofmolecularbiology indudesallexcept? a)Transcription b)Translation c)RNAreplication d)DNAreplication CorrectAnswer-CAns.is'c'i.e.,RNAreplicationDNAstoresgeneticinformation:-InformationaboutaminoacidsequenceofalltheproteinsispresentintheformofgenesinDNA.TheentiregeneticmaterialpresentintheDNAofanorganismisknownasgenome.TheimportantroleofDNAintransferofinformationinlivingcellsiscalledcentraldogmaofmolecularbiology.Accordingtothecentraldogma,informationflowsfromDNAtoRNAtoprotein.
557.Nucleotideconsistsofallexcept? a)Sugar b)Phosphate c)Fattyacid d)Base CorrectAnswer-CAns.is'c'i.e.,Fattyacid[RefHarper's28"/ep.286]Nucleotidesaremonomericunitsofnucleicacids.Theyarerequiredforsynthesisofnucleicacid.Eachnucleotideismadeupof:(i)Anitrogenousbase,(ii)Asugar(pentosesugar)and(iii)Aphosphategroup(phosphoricacid).Nitrogenousbasecombineswithasugartoformnucleosides.Thenucleosidecombineswithphosphoricacidtoformanucleotide.
558.Whichofthefollowingisrequiredfor fattyacidsynthesis? a)NADPH b)NADH c)FADH d)None CorrectAnswer-AAns.is'a'i.e.,NADPH[RefHarper29th/ep.216-217]FattyacidsynthesistakesplaceincytosolQ.Acetyl-CoAistheimmediatesubstrateforlipogenesisandsynthesisalwaysendsinformationofplamiticacie.Inhumans;liverandlactatingmammaryglandsarethemainorgansforlipogenesisQ.Althoughkidney,brain,lungsandadiposetissuearealsoinvolved,toalesserextent.CofactorrequirementsforfattyacidsynthesisareNADPH,ATP,Mr1.2,biotinandHCO3-(asasourceofCO2).Becausemostfattyacidshavemultiplesoftwocarbons,theyaresynthesizedfromsuccessiveadditionoftwocarbonunits,thedonorofwhichisacetyl-CoA.So,thebasicbuildingblockisacetyl-CoA?whichisthesourceofallthecarbonatomsofthefattyacidbeingsynthesized.
559.Shinedalgarnosequenceisrelatedto? a)Transcription b)Translation c)DNAreplication d)None CorrectAnswer-BAns.is'b'i.e.,TranslationShinedalgarnosequenceinprokaryotesandKozakconsensussequencesineukaryoteshelpsininitiationofproteinsynthesis(Translation)Inprokaryotes,asequenceofnucleotidebasesonmRNAknownasShine-Dalgarnosequence(SDsequence)facilitatesthebindingofmRNAtothepreinitiationcomplex.SDsequenceisapurine-richsequenceofnucleotidebases,whichislocated-6to-10bpfromAUGcodon?.InEukaryotes,'Kozakconsensus'sequencesurroundsAUG(initiationcodon)anddeterminestheinitiatingcodonofmRNA.
560.Citrateusedinfattyacidsynthesisuses whichenzyme? a)CitrateSynthase b)ATPcitratelyase c)Aconitase d)Malicenzyme CorrectAnswer-BAns.is'b'i.e.,ATPcitratelyase[RefHarper's28th/ep.193,196]Glucoseistheprimarysubstrateforlipogenesisandacetyl-CoA(immediatesubstrateforfattyacidsynthesis)isformedfromglucoseviaoxidationofpyruvatewithinthemitochondria.However,acetyl-CoAcannotpenetrateinnermitochondrialmembrane.Thereforeitistransferredintheformofcitrate.Citrateisformedinthemitochondrialmatrixbythecondensationofacetyl-CoAwithoxaloacetate(firstreactionincitricacidcycle).Thencitrateistransportedintocytosolviathetricorboxylatetransporterinexchangewithmalate.Incytosol,citrateiscleavedbyATP-citratelyasetooxaloacetateandacetyl-CoA.
561.Whichofthefollowingisw-6fattyacid- a)Cervonicacid b)Linoleicacid c)Alphalinolenicacid d)Elaidicacid CorrectAnswer-BAns.is'b'i.e.,Linoleicacid[RefHarper28th/ep.123]AlphalinolenicacidLinoleicacidOleicacidClupandonicacidGamalinolenicacidNervonicacidCervonicacidArachidonicacidElaidicacid
562.Linoleicacidis- a)w-3fattyacid b)w-6fattyacid c)w-9fattyacid d)Saturatedfattyacid CorrectAnswer-BAns.isb'i.e.,w-6fattyacid[RefHarper28thlep.123]
563.WatsoncrickmodelisforwhichDNA? a)BDNA b)ADNA c)CDNA d)ZDNA CorrectAnswer-AAns.is'a'i.e.,BDNA[Ref:Harper250/ep.344]DNAistherepositoryofgeneticinformation.DNAislocatedinnucleus.DNAisalsopresentinmitochondria
564.Lipogenesisoccursin? a)Liver b)Skeletalmuscles c)Myocardium d)Lungs CorrectAnswer-A:DAns.is'a>d'i.e.,Liver>LungsFattyacidsynthesistakesplaceincytosol?.Acetyl-CoAistheimmediatesubstrateforlipogenesisandsynthesisalwaysendsinformationofpalmiticacid.
565.Whichofthefollowingismonoenoicacid ? a)Arachidonicacid b)Linoleicacid c)Oleicacid d)Linolenicacid CorrectAnswer-CAns.C.OleicacidInhumans;liverandlactatingmammaryglandsarethemainorgansforlipogenesisQ.Althoughkidney,brain,lungsandadiposetissuearealsoinvolved,toalesserextent.CofactorrequirementsforfattyacidsynthesisareNADPH,ATP,Mn.2,biotinandHCO3-(asasourceofCO).Becausemostfattyacidshavemultiplesoftwocarbons,theyaresynthesizedfromsuccessive
566.Whichofthefollowingisnotinvolvedin synthesisofpyrimidines? a)Glutamine b)CO c)Asparticacid d)Glycine CorrectAnswer-DAns.is'd'i.e.,Glycine[RefHarper29th/ep.336-337]AminoacidsinvolvedinpurinesynthesisGlycine,aspartate,glutamine.AminoacidsinvolvedinpyrimidinesynthesisGlutamine,asparticacid(aspartate)
567.Whichofthefollowingfattyacidhas maximumnumberofcarbonatoms? a)Oleicacid b)Linolenicacid c)Arachidonicacid d)Cervonicacid CorrectAnswer-DAns.is'd'i.e.,CervonicacidCervonicacidhas22carbonatoms,morethanoleicacid(18C),linolenicacid(18C)andarachidonicacid(20C).So,thebasicbuildingblockisacetyl-CoAQwhichisthesourceofallthecarbonatomsofthefattyacidbeingsynthesized.
568.Chylomicronremnantsareassociated with? a)Apo-A b)Apo-B100 c)Apo-E d)Apo-C CorrectAnswer-CAns.is'c'i.e.,Apo-E
569.Purineareformedby? a)Asparticacid,glycine,uricacid b)Aspartate,glycine, c)Aspartate,glutamate d)Aspartate,glycine,glutamine CorrectAnswer-DAns.is'd'i.e.,Aspartate,Glycine,Glutamine[RefHarper29thiep.332]AminoacidsinvolvedinpurinesynthesisGlycine,aspartate,glutamine.AminoacidsinvolvedinpyrimidinesynthesisGlutamine,asparticacid(aspartate).
570.Apoprotein-C? a)Activateslipoproteinlipase b)Inactivateslipoproteinlipase c)Facilitatestriglyceridetransport d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,Alloftheabove[RefHarper28th/ep.213]ApoC-IIisanactivatorofLPL,wherasapoA-IIandapoC-IIIactasinhibitorsofLPL.Asapo-CisacomponentofchylomicronsandVLDL,itfacilitatestransportofTGs.
571.Whichisnottrueofchylomicrons? a)Lowestdesnsity b)Max.contentisTGs c)Max.contentischolesterol d)Largestsize CorrectAnswer-CAns.is'c'i.e.,Max.contentischolesterol[Ref:Harper29th/ep.238,Chatterjea8thlep.445,446]
572.Beta-alanineisderivedfrom? a)Adenosine b)Guanosine c)Thymine d)Uracil CorrectAnswer-DAns.is'd'i.e.,Uracil[Ref:Harper29illep.339,340]
573.OxidisedLDLismoreathreogenic because? a)BindstoApoE b)BindstoscavengerR c)BindstoATPbinding d)Accumulatesinmacrophages CorrectAnswer-DAns.is'd'i.e.,Accumulatesinmacrophages[RefRobbin's8thlep.837]MacrophagesengulfLDLcholesterolandformfoamcellsformationofearliestlesion,i.e.fattystreak.MacrophagesalsoformoxygenfreeradicalsthatcauseoxidationofLDLtoyieldoxidizedLDL(modifiedLDL).
574.Adeninephosphoribosyltransferaseis involved? a)Denovopurinesynthesis b)Purinedegradation c)Salvagesynthesisofpurinenucleotides d)None CorrectAnswer-CAns.is'c'i.e.,Salvagesynthesisofpurinenucleotides[RefHarper29thiep.334-335]SalvagepathwayofpurinenucleotidesynthesisFreepurinebases(adenine,guanineandhypoxanthine)andpurinenucleosidesareformedincellsduringthemetabolicdegradationofnucleicacidsandnucleotides.Thesefreepurinebasesandpurinenucleosidesarereusedintheformationofpurinenucleotides.Thisiscalledsalvagepathway(salvagemeanspropertysavedfromloss).Salvagesynthesisrequiresfarlessenergythandenovosynthesis.
575.Hormonesensitivelipaseisinhibitedby? a)Thyroidhomone b)Insulin c)GH d)ACTH CorrectAnswer-BAns.is`b'i.e.,Insulin[RefHarper29"Vep.246,247]
576.Lecithinehydrolysisyeilds? a)Choline b)Pyruvate c)Glycine d)None CorrectAnswer-AAns.is'a'i.e.,Choline[RefHarper29th/ep.233]
577.Whichofthefollowingrequiresvitamin BIZ? a)Serinetolysine b)Homocysteinetomethionine c)Serinetoglycine d)Glutaminetoglutamate CorrectAnswer-BAns.is'b'i.e.,Homocysteinetomethionine[Ref:Harper2967ep.537-539]ConversionofhomocysteintomethionineInthisreaction,activeformismethylcobalamine.ThisistheonlyreactionwhichrequiresbothvitaminB,2(asmethylcobalamine)andfolicacid(asN5-methyl-Hdolate).Thereactioniscatalyzedbytheenzymecobalamin-dependentmethioninesynthasealsocalled5-methyltetrahydrofolate-homocysteinemethyltransferase
578.Thepyruvateutilizationintissuesis decreasedin? a)Perniciousanemia b)Scurvy c)Beriberi d)Pellagra CorrectAnswer-CAns.is'c'i.e.,Beriberi[RefHarper29th/ep.534]Pyruvateutilizationisdecreasedinthiaminedeficiency.Beriberiisduetothiaminedeficiency.Inthiaminedeficiency,pyruvatecannotbeconvertedtoacetyl-CoAasthiaminepyrophosphateisacoenzymeforpyruvatedehydrogenasewhichcatalyzestheconversionofpyruvatetoacetyl-CoA.Hence,excessofpyruvateismetabolizedtolactatebylactatedehydrogenase
579.Coenzymeformofpyridoxineis? a)ADP b)NAD c)PLP d)FAD CorrectAnswer-CAns.is'c'i.e.,PLP[RefGuyton12thiep.854]
580.Omegaoxidationoffathyacidsoccur? a)ER b)Mitochondria c)Cytosol d)None CorrectAnswer-AAns.is'a'i.e.,ER[RefHarper's28th/ep.185,195]Beta(a)MitochondriaAlpha(a)Endoplasmicreticulum,MitochandriaOmega(w)Microsomalsystem(smoothER)a-oxidationofverylongchainFAPeroxisomes
581.Mostpotentantioxidant? a)VitA b)VitK c)VitE d)VitC CorrectAnswer-CAns.is'c'i.e.,VitE[Ref:Harper29thiep.532,541,543]Amongstgivenoptions,vitaminA,EandCareanti-oxidants.However,VitaminE(tocopherol)isthemostimportantantioxidantinthebody,actinginthelipidphaseofmembranesprotectingagainsttheeffectsoffreeradicals.
582.Whatistrueregardingmediumchain fattyacids? a)Don'trequirepancreaticlipase b)Notdepositedinadiposetissue c)Diffusedirectlyintoportalcirculation d)Alloftheabove CorrectAnswer-DAns.is'd'i.e.,Alloftheabove[RefVasudevan6"p.160]Metabolismofshortchainfattyacids(SCFAs)andmediumchainfattyacids(MCFAs)isdrasticallydifferentfromlongchainfattyacids(LCFAs).SCFAsandMCFAsdonotrequirepancreaticlipaseandbilesaltsfordigestion,butrequiredforLCFAsdigestion.SCFAsandMCFAsaredirectlyabsorbedfromintestineintoportalcirculation,whereasLCFAsaretakenbylymphatics,afterincorporationintochylomicrons.SCFAsandMCFAsareoxidizedbyperipheralcellsandarenotusedforstorage.LCFAsareesterifiedwithglyceroltoformtriacylglycerol,storageformoflipid
583.Whatwillyougivetostopchyluriain diet? a)SmallchainFA b)MediumchainFA c)LongchainFA d)Omega3unsaturatedFA CorrectAnswer-BAns.is'b'i.e.,MediumChainFA[RefHarrison's18thiep.294]Mediumchainfattyacidsdirectlyentertheportalveinonabsorption,bypassingthelymphatics.Hence,theyareusedinchyluria
584.Pantothenicacidisneededfordonating thefollowingmoiety? a)Acetyl(oracyl)CoA b)Carboxyl c)Hydroxyl d)Amino CorrectAnswer-AAns.is'a'i.e.,Acetyl(oracyl)CoA[RefHarper29th/ep.540]PantothenicacidfunctionsascoenzymebyprovidingbuildingblockofcoenzymeAandACP 1. Coenzyme-Aparticipatesinreactionsofcitricacidcycle,fattyacid oxidation,acetylation,andcholesterolsynthesis. 2. ACPtakespartinfattyacidsynthesis
585.Ascorbicacidisrequiredforsynthesisof ? a)Phenylserine b)Homoserine c)Hydroxylysine d)Selenocysteine CorrectAnswer-CAns.is'c'i.e.,Hydroxylysine[RefHarper's29th/ep.540]Hydroxylationofprolineandlysineresiduetakesplaceduringpost-translationalmodificationinroughER.Theenzymecatalyzingthereactionsareprolylhydroxylase(forproline)andlysylhydroxylase(forlysine).Boththeseenzymesaredioxygenases?usingmolecularoxygen(02)andcofactorforboththeseenzymesisvitaminC(ascorbicacid)?.a-Ketoglutatrateisacoreductant,whichisoxidizedtosuccinate.
586.Inapersonfastingovernightwith carnitinedeficiency,followingchemicalsincreaseinquantityinblood? a)Glucose b)Fattyacids c)Aminoacids d)Ketonebodies CorrectAnswer-BAns.is'b'i.e.,Fattyacids[Ref:Harper29th/ep.208-209,214]Instarvation,thereisincreasedhydrolysisofTGs(ofadiposetissues)intoglycerolandfattyacids.Fattyacidsarefurtheroxidizedby[3-oxidationinthemitochondria.Carnitineisrequiredfortransportedofactivatedfattyacidintomitochondriafor3-oxidation.Ifcarnitineisdeficient,fattyacidscannotbetransferredintothemitochondria,buttheyarecontinuouslyproducedduetohydrolysisofTGs(instarvationthereisdecreasedinsulintoglucagonratio,whichstimulateshydrolysisofTGs).Thusfreefattyacidlevelisincreasedasthereisincreasedproductionbutnoutilization(p-oxidation).
587.WhichofthefollowingisaFatSoluble vitamin? a)Thiamine b)Niacine c)VitaminA d)Ribaflavin CorrectAnswer-CAns.is'c'i.e.,VitaminA[RefHarper's296/ep.335]
588.Serumappearymilkywhitein? a)IncreasedLDL b)IncreasedHDL c)IncreasedVLDL d)IncreasedChylomicrons CorrectAnswer-DAns.is'd'i.e.,IncreasedChylomicrons[RefHarrison18thlep.3151]"Thefastingplasmaisturbid,andifleftat4?C(39.2?F)forafewhours,thechylomicronsfloattothetopandformacreamysupernatant".Chylomicronsarethelargestlipoproteinmoleculewithmaximumlipidcontents.Therefore,theyhaveleastdensityandfloatonthetopgivingacreamy(milky)supernatant.
589.Overnightfastingwhatoccurs? a)Glucosedecreases b)FFAincreases c)Increasedgluconeogenesis d)Increasedbeta-hydroxybutyrate CorrectAnswer-CAns.is'c'i.e.,Increasedgluconeogenesis[RefVasudevan&hiep.85,86,Harper28th/ep.240,241]Inovernightfastingglucoselevelismaintainedduetoglycogenolysisandgluconeogenesis.FFAandketonebodies(p-hydroxybutyrate)startsrisingafter2-3days,i.e.inlaterpartofinitialstageofprolongedstarving
590.Adiposetissuefatmetabolismisdoneby ? a)Lipoproteinlipase b)Hormonesensitivelipase c)Acidlipase d)Acidmaltase CorrectAnswer-BAns.is'bi.e.,Hormonesensitivelipase[Ref:Harper29th/echap.16]Adiposetissuefat(TGs)metabolismHormonesensitivelipaseLipoproteins(VLDL&chylomicrons)TGsmetabolism-Lipoproteinlipase
591.RQisleastin? a)Brain b)RBC c)Adipose d)Heart CorrectAnswer-DAns.is'd'i.e.,Heart[RefReadbelow]Respiratoryqnotient(RQ)of: 1. Carbohydrateis12. Fatis0.703. Proteinis0.82 Undernormalconditionthemajorfuelofheartisfattyacids,whileotherthreeorgans(giveninoptions)utilizeglucose.ThusRQvalueisminimumforheart.
592.EnzymedeficientinTypeI Hyperlipidemiais? a)HMGCoAreductase b)Lipoproteinlipase c)Cholesterolacyltransferase d)Peroxidase CorrectAnswer-BAns.is'b'i.e.,Lipoproteinlipase[Ref:Harper2e/ep.232table(26.1)]
593.Apo-Edificiencyisseenin a)TpyeIhypolipoproteinemia b)TpyeIIhypolipoproteinemia c)TpyeIIIhypolipoproteinemia d)TpyeIVhypolipoproteinemia CorrectAnswer-CAns.is'c'i.e.,TpyeIIIhypolipoproteinemis[RefHarisonp.3149,3150,Chatterjea8th/ep.45]
594.Substancewithhighestthermogenic effect? a)Fat b)Proteins c)Carbohydrate d)Allarethesame CorrectAnswer-BAns.is`b'i.e.,Proteins[RefProgressinobesityresearch-397]Thermogeniceffect(thermiceffect)offoodreferstotheincreaseinmetabolicratethatoccursafteringestionofparticularfood.Thisresultsinanincreaseintheamountofheatgeneratedbythebody.Proteinisatthetopofthehierarelyofmacronutrients,asforasthethermogeniceffectinconcerned.About25-30%ofenergyisconsumedtodigesttheprotein.Carbohydratescomeinthemiddleandlipids(fats)areinthirdplace.
595.Anapleroticreactioniscatalyzedby? a)Pyruvatecarboxylse b)Enolase c)Pyruvatekinase d)G6PD CorrectAnswer-AAns.is'a'i.e.,Pyruvatecarboxylse[RefDineshPuri3`diep.177]Conversionofpyruvatetomalatebythecytoplasmicmalic-enzyme.MalatecanthenenterthemitochondrionasasubstratefortheTCAcycle.Pyruvatemayreactwithaspartateorglutamateintransaminasereactions,producingtheTCAcycleintermediatesoxalocetateanda-ketogluarate,respectively.SeveralglycogenicaminoacidsmayserveassourceofTCAintermediates
596.Whichofthefollowingisnotaffectedin Abetalipoproteinemia? a)LDL b)VLDL c)HDL d)IDL CorrectAnswer-CAns.is'c'i.e.,HDL[RefChatterjea8thlep.462,463&DineshPuri3rdlep.248]HypolipoproteinemiaInthisgroupofdisordersconcentrationofoneormorelipoproteinsinplasmaisdecreased.Thecommonestofthesedisordersareabetalipoproteinemia,hypobetalipoproteinemiaandhypoalphalipoproteinemia.Abetalipoproteinemia:-Thereisdefectivesynthesisorsecretionofapoprotein-B(apo-B)inintestineandliver.So,thereisdeficiencyofapo-Bcontaininglipoproteinsi.e.chylomicrons?,VLDL?,IDL?andLDL?.Asaresultextremelylowplasmalevelsofcholesterolandtriacylglycerols?occurs.HDLlevelsarenormal?asHDLdoesnotcontainapo-B.Hypobetalipoproteinemia:-Thereisdecreasedsynthesisofapo-Bduetoapo-Bgenemutations.So,apo-Bcontaininglipoproteinsaresynthesizedatlowerrate.ThereisslightdecreaseinVLDL,IDLandLDLlevels.HDLisnormal.Plasmacholesterolandtriglyceridesaredecreased.Hypoalphalipoproteinemia(Tangierdisease):-ThereismarkeddeficiencyofmajorlipoproteinHDL(apo-A-Iandapo-A-II),
probablybecauseofacceleratedcatabolism.
597.InZellwegersyndrome,thereis? a)Accumulationoflongfattyacids b)Accumulationofshortchainfattyacids c)Accumulationofverylongchainfattyacids d)Accumulationofmediumchainfattyacids CorrectAnswer-CAns.is'c'i.e.,Accumulationofverylongchainfattyacids[RefHarper29m/ep.554;Chatterjea6thlep.412]ZellwegerSyndromeisarareinbornerrorofperoxisomalfattyacidoxidation?duetoabsenceoffunctionalperoxisomesinalltissues.Asaresult,thelongchainfattyacidsarenotoxidizedinperoxisomesandaccumulateintissuesparticularlyinbrain,liver,kidneyandmuscleandusuallyresultindeathbyagesix.
598.Autooxidationisseenin? a)Cholesterol b)Arachidonicacid c)Stearicacid d)Palmiticacid CorrectAnswer-BAns.is'b'i.e.,Arachidonicacid[RefEssentialofbiochemistryp.736]Polyunsaturatedfattyacids(PUFAs)undergoperoxidation(auto-oxidation).Amongstthegivenoptions,onlyarachidonicacidisPUFA.
599.Whichofthefollowingisalipotropic factor:? a)Sphingomyelin b)Histidine c)Methionine d)Bilirubin CorrectAnswer-CAns.is'c'i.e.,Methionine[RefEssentialsofbiochemistry/p.761]Lipotropicfactorsaresubstanceswhichpreventaccumulationoffat(TGs)inliver.Primarylipotropicfactorscholine,betaine,methionine,lecithine,inositol.Otherfactorswithsomelipotropicaction:-Vitamin-13,2,folicacid,casein,glycine,essentialfattyacids,selenium,vitaminEandserine.
600.Lipogenesisisstimulatedby? a)Insulin b)Glucagon c)Epinephrine d)Corticosteroids CorrectAnswer-AAns.is'a'i.e.,Insulin[RefDineshPuri3rdiep.318]
601.Indoleringispresentin? a)Tryptophan b)Tyrosine c)Phenylalanine d)Threonine CorrectAnswer-AAns.is'a'i.e.,Tryptophan[Ref:Lehninger4thIep.80]Someaminoacidscontainaspecialfunctionalgroupintheirsidechainwhichprovidesomespecificfunctionstothataminoacids.Theseare:- Hydroxylgroupinserineand Guanidiniumin Imidazolein threonine arginineQ histidine Amidegroupinaspargineand Benzenein Phenolin glutamine phenylalanine tyrosine Indoleringin Pyrrolidinein Thioetherinmethionine tryptophanQ proline 13-Carboxylin E-aminoin Sulphydrylincysteine glutamicacid lysine y-carboxylinglutamicacid
602.Taurineisbiosynthesizedby? a)Arginine b)Leucine c)Valine d)Cysteine CorrectAnswer-DAns.is'd'i.e.,Cysteine[RefHarper250/ep.298-99]Taurineissynthesizedfromcysteineby3enzyme-catalyzedreactions: 1. Cysteineisoxidizedtocysteinesulfinate.2. Cysteinesulfinateisdecarboxylatedtoformhypotaurine.3. Hypotaurineisoxidizedtoformtaurine
603.Whichofthefollowingistrue? a)Glucokinasehashighaffinityforglucose b)Hexokinasehaslowaffinityforglucose c)Glucokinasehaslowaffinityforglucose d)Hexokinaseisinducedbyinsulin CorrectAnswer-CAns.is'c'i.e.,Glucokinasehasloweffinityforglucose[RefHarper28`"/ep.151-152]Glucokinase,isspecificforglucose.IthashighKinQ(i.e.,lowaffinityforglucose),highVmaxandunlikehexokinase,itisnotinhibitedbyglucose-6-phosphateQ.Asithaslowaffinityforglucose(highkm),itcomesintoplayonlywhenintracellularglucoseconcentrationishigh.Itisinducedbyfeedingandinsulin.Glucagoninhibitsglucokinase.Functionofhexokinaseistoprovideglucose-6-phosphateataconstantrate,accordingtheneedsofcells,i.e.,functionofhexokinaseistoprovideconstantglucoseutilizationbyalltissuesofbodyevenwhenbloodsugarislow.Functionofglucokinaseintheliveristoremoveglucosefrombloodafterameal,providingglucose-6-phosphateinexcessofrequirementforglycolysissothatitcanbeusedforglycogensynthesisandlipogenesis.
604.Methylmalonylaciduriaisseenin deficiencyof? a)VitB12 b)VitB6 c)VitC d)Folicacid CorrectAnswer-AAns.is'a'i.e.,VitB12[RefHarper29"Vep.537]IsomerizationofmethylmalonylCoAtosuccinylCoA:Inthisreaction,activeformofvitaminBI2isdeoxyadenosylcobalamine.Propionyl-CoAisproducedascatabolicendproductofsomealipathicaminoacidsandn-oxidationofoddchainfattyacids.PropionylCoAisthenconvertedtosuccinylCoAthroughmethylmalonyl-CoA.Thusmethylmalonyl-CoAisaccumulatedandexcretedinurineasmethylmalonicacid(methylmalonate)invitaminB12deficiency0,i.e.methylmalonicacidurie
605.Carnitineissynthesisedfrom- a)Lysine b)Agrinine c)Histidine d)Choline CorrectAnswer-ATrimethyllysineand-butyrobetainehydroxylasesarerequiredforthesynthesisofcarnitine
606.Chemiosmoticcouplingofoxidation phosphorylationisrelatedto? a)FormationofATPatsubstratelevel b)ATPgenerationofpumpingofproton c)ATPgenerationofpumpingofneutron d)ATPformationbytransportof0, CorrectAnswer-BAns.is'b'i.e.,ATPgenerationofpumpingofproton[RefHarper29'diep.125-127]ChemoiosmotictheoryItstatesthat"freeenergyofelectrontransport"isconservedbypumpingprotonsfrommitochondrialmatrixtotheintermembranespace,soastocreateanelectrochemicalprotongradientacrosstheinnermitochondrialmembrane,withoutersideofmembraneispositivelychargedascomparedtoinside.ElectrochemicalpotentialofthisgradientisusedtosynthesizeATPbyATPsynthase
607.Whichoneofthefollowingstatements concerninggluconeogenesisiscorrect? a)Itoccursinmuscle b)Itisstimulatedbyfructose2,6-bisphosphate c)ItisinhibitedbyelevatedlevelsofacetylCoA d)Itisimportantinmaintainingbloodglucoseduringthenormal overnightfast. CorrectAnswer-DAns.is'd'i.e.,Itisimportantinmaintainingbloodglucoseduringthenormalovernightfast[RefMark'sBasicmedicalbiochemistryp.566]Duringfasting,manyofthereactionsofglycolysisarereversedastheliverproducesglucosetomaintainbloodglucoselevels.Thisprocessofglucoseproductioniscalledgluconeogenesis.Duringovernightfast,bloodglucoselevelsaremaintainedbybothgluconeogenesisandglycogenolysis.However,afterapproximately30hoursoffasting,liverglycogenstoresaremostlydepleted.Subsequently,gluconeogenesisistheonlysourceofbloodglucose.
608.Fattyacidmetabolismgives? a)AcetylCoA b)MalonylCoA c)Ketonebodies d)Cholesterol CorrectAnswer-AAns.is'a'i.e.,AcetylCoA[RefHarper250/ep.208-210]Acetyl-CoAhasaspecialcentralrole.Acetyl-CoAisthecommondegradationproductofglucose(byglycolysisQandPDHcomplex),fattyacidsandketogenicaminoacids.ItsacetylgroupcanbeutilizedinsynthesisoffattyacidsQ,cholesterolQandothersteroidsQ,ketonebodiesQ;orcanbeoxidizedviaTCA(citricacidcycle).Infedstateacetyl-CoAisoxidisedviaTCAcycleandusedforsynthesisoffattyacidsandcholesterolQ,whereasinstarvationitisusedtosynthesizeketonebodiesQ
609.Tyrsoineistheprecursorofallexcept? a)Thyroxine b)Melanin c)Dopmine d)Nicotinicacid CorrectAnswer-DAns.is'd'i.e.,Nicotinicacid[Ref:Harper's28th/ep.266,268,254]Tyrosineisaprecursorofmanyimportantcompoundssuchascatecholamines(epinephrineQ,norepinephrineQ),dopamine),thyroxineQ,triiodothryonine,melanin0.
610.Organwhichcanutilizeglucose,FAand ketonebodiesis- a)Liver b)Brain c)Skeletalmuscle d)RBC CorrectAnswer-CAns.is'c'i.e.,Skeletalmuscle[RefHarper28th/ep.141]Skeletalmusclescanutilizeglucose,glycogen,fattyacidsandketonebodies.Livercannotutilizeketonebodies.Brainanderythrocytesareexclusivelydependentonglucoseexceptinprolongedstarvationwherebrainutilizesketonebodiespredominantly
611.Whichofthefollowingenzymeisnot usedbyliverinureacycle? a)CPS-I b)CPS-II c)Arginase d)Arginosuccinate CorrectAnswer-BAns.is'b'i.e.,CPS-II[RefHarper29th/ep.277-278]CarbmoylphosphatesynthaseII(CPSII)isinvolvedinpyrimidinesynthesis(notinureacycle).
612.HMG-CoAinlivermitochondriais inhibitedby? a)Insulin b)Glucagon c)Glucocorticoid d)Epinephrine CorrectAnswer-AAns.is'a'i.e.,InsulinThisquestionisalittletricky.EffectofinsulinonketogenesisKetogenesisisusuallyassociatedwithexcessivefattyacidoxidation(lipolysis)whichprovidesthesubstrate(acetyl-CoA)forketogenesis.Thus,factorswhichinhibitlipolysiswillinhibitketogenesis(andalsoproductionofHMG-CoA).Insulinisanantilipolytichormone.Itinhibitslypolysisandthereforeketogenesis.ThusitdecreasesthesynthesisofHMGCoAinketogenesis.So,insulininhibitsaswellasstimulatesproductionofHMG-CoA.Thenwhyisinsulintheanswerofthisquestion?Herecomesthetrickypartofthisquestion.ReadthequestioncarefullyexaminerhasaskedaboutHMG-CoAproductioninlivermitochondria.Ketogenesisoccursinmitochondria.CholesterolsynthesisoccursincytosolandsmoothER.ThusinsulininhibitsHMG-CoAproductioninmitochondriabutstimulatesitincytosol.
613.Aminoacidusedbyliverinureacycle? a)Glutamine b)Glutamate c)Aspartate d)Fumarate CorrectAnswer-CAns.is'c'i.e.,Aspartate[RefHarper29`"/ep.276-278]Thesourceoftwonitrogenatomsofurea->onefromammonia?andonefromaminogroupofaspartate?.SourceofcarbonisCO,Q.Thusoutofallaminoacidsinvolvedinureacycleaspartateisconsumed,whilethereisnonetlossorgainofornithine,citrulline,arginosuccinateorarginine.Thereisproductionoffumarateasbyproduct?.3moleculesofATPareconsumed(2infirstreactionand1inthirdreaction).However,4highenergyphosphatebondsareutilizedas3rdATPisconvertedtoAMP+PPi.
614.Hydrolysisoccursatwhichstepofurea cycle? a)Cleavageofarginine b)FormationofArginosuccinate c)Formationofcitrulline d)Formationofornithine CorrectAnswer-AAns.'A',CleavageofarginineUreasynthesisisa5stepcyclicprocess,with5distinctenzymes.Thefirst2enzymesarepresentinmitochondriawhiletherestarelocalizedinthecytosolStep1.FormationofCarbamoylPhosphate-OnemoleculeofammoniacondenseswithCO2inthepresenceoftwomoleculesofATPtoformcarbamoylphosphate.Itiscatalyzedbycarbamoylphosphatesynthetase-I(CPS-I).Step2.FormationofCitrulline-ThecarbamoylgroupistransferredtotheNH2groupofornithinebyornithinetranscarbamoylase.Step3.FormationofArgininosuccinate-Onemoleculeofasparticacidaddstocitrullineformingacarbontonitrogenbondwhichprovidesthe2ndnitrogenatomofurea.Argininosuccinatesynthetasecatalyzesthereaction.Step4.FormationofArginine-Argininosuccinateiscleavedbyargininosuccinatelyase(argininosuccinase)toarginineandfumarate.Theenzymeisinhibitedbyfumarate.ThefumarateformedmaybefunneledintotheTCAcycletobeconvertedtomalateandthentooxaloacetatetobetransaminatedtoaspartate.ThustheureacycleislinkedtotheTCAcyclethroughfumarate.
Step5.FormationofUrea-Thefinalreactionofthecycleisthehydrolysisofargininetoureaandornithinebyarginase.
615.Whycitricacidcyclecalledamphibolic pathway? a)Bothexergonicandendergonicreactionstakesplace b)Metabolitesareutilizedinotherpathways c)Itcanproceedbothinforwardandbackwarddirection d)Sameenzymescanbeusedinreversedirections CorrectAnswer-AAns.is'a'i.e.,Bothexergonicandendergonicreactionstakesplace[Ref:Harper29th/ep.151,166]Citricacidcycleiscalledamphibolicpathwaybecauseitactsasalinkbetweenanabolic(endothermic)andcatabolic(exothermic)pathways.
616.Urea&Kreb'scyclearelinkedat? a)Arginine b)Ornithine c)Oxaloacetate d)Fumarate CorrectAnswer-DAns.is'd'i.e.,Fumarate[RefHarper250/ep.276-277]Fumarateisreleasedduringureacycle,whichisanintermediateofKreb'scycle,thuslinkingthetwo.
617.Whichofthefollowingmetabolitesis involvedinglycogenolysis,glycolysisandgluconeogenesis? a)Galactose-l-phosphate b)Glucose-6-phosphate c)Uridinediphosphoglucose d)Fructose-6-phosphate CorrectAnswer-BAns.is'b'i.e.,Glucose-6-phosphate[RefHarper28thlep.166,158]Glucose-6-phosphateisthemetabolitewhich:? 1. Joinsglycolysiswithglycogenesisandglycogenolysis2. Joinsglycogenolysistopentosephosphatepathway(PPP)3. Isinvolvedinglycolysis,glycogenesisandgluconeogenesis, glycogenolysis,gluconeogenesis,PPP
618.Whichwillactivatecarbomoylphosphate synthaseI? a)Alanine b)N-acetylglutamate c)Ornithine d)None CorrectAnswer-BAns.is'b'i.e.,N-acetylglutamateCarbamoylphosphatesynthase-I(CPS-I),amitochondrialenzyme,catalyzestheformationofcarbamoylphosphate?bycondensationofCO2andammonia.TwomoleculesofATParerequiredforthereaction.CPS-IistheratelimitingenzymeofureacycleQ.ItisanallostericenzymeandallostericallyactivatedbyN-acetylglutamate
619.EnzymedeficientinIsovalericacidemia a)IsovalerylCoAdehydrogenase b)Phenylalaninehydroxylase c)Arginase d)None CorrectAnswer-AAns.is'a'i.e.IsolvalerylCoAdehydrogenase-Isovalericacidemiaisduetothedefectinthemetabolismofleucine.-TheenzymedefectiveisisovalerylCo-Adehydrogenase.-Acharacteristicodorofsweatyfeetispresent.-Vomiting,acidosis,andcomafollowtheingestionofexcessprotein.Accumulatedisovaleryl-CoAishydrolyzedtoisovalerateandexcreted.
620.TransaminationofAlanineresultsin formationof? a)Oxaloacetate b)Pyruvate c)Aspartate d)Arginine CorrectAnswer-BAns.is'b'i.e.,Pyruvate
621.Trueaboutalkaptonuria? a)DeficiencyofTyrosinase b)Urineisblack c)Banedicttestisnotuseful d)Fecl,testgivesredcolour CorrectAnswer-BAns.is'b'i.e.,Urineisblack[RefNelson18thiep.1812]
622.Cofactorsforglutamatedehydrogenase? a)NAD+ b)FAD c)FMN d)FADH2 CorrectAnswer-AAns.'A'NAD+AnaerobicDehydrogenasesaretheenzymesthatcatalyzetheremovalofhydrogenfromasubstratebutoxygencannotactasthehydrogenacceptor.They,therefore,requirecoenzymesasacceptorsofthehydrogenatoms.Whenthesubstrateisoxidized,thecoenzymeisreduced.NAD+isderivedfromnicotinicacid,amemberofthevitaminBcomplex.TheNAD+linkeddehydrogenasesare-Glyceraldehyde-3-phosphatedehydrogenaseIsocitratedehydrogenaseMalatedehydrogenaseGlutamatedehydrogenaseBetahydroxyacylCoAdehydrogenasePyruvatedehydrogenaseAlpha-ketoglutaratedehydrogenase
623.Ochronosisisduetoaccumulationof? a)Homogentisicacid b)Phenylpyruvate c)Xanthurenate d)Glyoxylate CorrectAnswer-AAns.is'a'i.e.,Homogentisicacid[Ref:Harper29th/ep.287-289]AlkaptonuriaItisduetodeficiencyofhomogentisateoxidase.Asaresulthomogentisicacid(homogentisate)isexcretedexecessivelyinurine.Therearethreeimportantcharacteristicfeaturesinalkaptonuria? 1. UrinebecomesdarkafterbeingexposedtoairQ.Itisdue spontaneousoxidationofhomogentisateintobenzoquinoneacetate,whichpolymersetoformblack-brownpigmentalkaptonwhichimpartsacharacteristicblack-browncolourtourine. 2. Alkaptondepositionoccursinsclera,ear,nose,cheeksand intervertebraldiscspace.Aconditioncalledochronosis.TheremaybecalcificationofintervertebraldiscsQ. 3. Onchronosisarthritisaffectingshoulder,hips,knee.4. Benedict'stestisstronglypositiveinurineandsoistheferric chloride(Pea)testQ.Benedict'sreagentgivesagreenishbrownprecipitatewithbrownishblacksupernatent.Fehling'sreagent(FeC13)givesbluegreencolour.
624.Neonataltyrosenemiaisdueto deficiencyof? a)Tyrosinase b)Fumarylacetoacetatehyroxyase c)Hydroxyphenylpyruvatehydroxylase d)Tyrosinetransminase CorrectAnswer-CAns.is'c'i.e.,Hydroxyphenylpyruvatehydroxylase[RefHarper's28th/ep.266,268]TyrosinemiaItisadefectinmetabolismoftyrosine.Itmaybeoffollowingtypes. 1. Tyrosinemiatype-I(tyrosinosis/hepatorenalsyndrome):-Itisdueto defectinfumarylacetoacetatehydroxylasedeficiency.Patientswithchronictyrosinosisarepronetodevelopcirrhosisandhepaticcarcinoma?.Thereiscabbagelikeodorinacutetyrosinosis. 2. Tyrosinemiatype-II(Richer-Hanhartsyndrome):-Itisdueto deficiencyoftyrosinetransaminaseQ(tyrosineaminotransferase). 3. Neonataltyrosinemia:-Itisduetodeficiencyof hydroxyphenylpyruvatehydroxylase.
625.Separationofproteinsbytheirmass? a)Electrophoresis b)Saltingout c)SDS-PAGE d)Ionexchangechromatography CorrectAnswer-CAns.is'c'i.e.,SDS-PAGE[RefVasudevan6"diep.600]
626.AboutDenaturationofprotein,whichis true? a)Biologicalpropertypersists b)Primarystructurelost c)Alwaysirreversible d)Mostlyrendersproteininsoluble CorrectAnswer-DAns.is'd'i.e.,Mostlyrendersproteininsoluble[RefLippincott's4thIep.57]Thetermdenaturationreferstodisruptionofhigherorder(secondary,tertiaryandquaternary)structureofprotein.Allnon-covalentbondsthatmaintainhigherorderstructurearedisrupted,butpeptidebond(covalentbond)remainsintact.Thus,theprimarystructureisnotalteredduringdenaturation,i.e.,aminoacidsequenceisnotaltered,butdenaturationmaycompletelydisruptsecondary,tertiaryandquaternarystructure,e.g.,denaturatedoligomericproteinsdissociatedintosubunits,eachwitharandamcoilformation.Denaturationisalwaysaccompaniedbyalossofbiologicalfunction,e.g.,enzymesareinactivatedandantibodiesfailtoactwithantigens.Denaturationisgenerallyirreversible,e.g.,boiledeggdoesnotregainitsoriginalformwhenkeptincold.Denaturedproteinsarelesssolubleandinmanycasestheyprecipitate.
627.Twosamechargedproteinscanbe separatedbyallexcept- a)Agarose b)DEAECellulose c)Sephadex d)Noneofthese CorrectAnswer-BAns.is'b'i.e.,DEAECellulose[RefEssentialsofBiochemistryp.670,795]DEAEcellulosechromatography(anionexchange)separatesmoleculesbasedonmolecularcharge.Therefore,itcannotseparatetwoproteinswithsamecharge.Agarose(sepharose)anddextran(sephadex)areusedingelfiltrationchromatography,whichisbasedonmolecularsize.Thus,theycanseparateproteinsofsamecharge.
628.Inglycolysis,inorganicphosphateis usedreaction,catalyzedby? a)Enolase b)Pyruvatekinase c)Glyceraldehyde-3-pdehydrogenase d)Aldolase CorrectAnswer-CAns.is'c'i.e.,Glyceraldehyde-3-pdehydrogenase
629.250nmlightisabsorbedby? a)Arginine b)Alanine c)Tyrosine d)Histidine CorrectAnswer-CAns.is'c'i.e.,TyrosineAminoacidsdonotabsorbvisiblelightandthusarecolourless.However,aromaticaminoacidsQ(tryptophan,tyrosine,phenylalanine)absorbhigh-wavelength(250-290nm)UVlight.Trypytophanhasthegreatestabsorptionmaximainthisregionthanothertwoaromaticaminoacids.Thus,aromaticaminoacidsareresponsibleforUVabsorptionofmostproteins0,maximumabsorptionbeingat280rim.
630.Tyrosinosisiscausedduetodeficiency ofwhichenzyme? a)Fumarylacetoacetatehydrolase. b)p-hydroxyphenylpyruvatedehydrogenase. c)Tyrosinetransaminase. d)Tyrosineligase. CorrectAnswer-AAnswer:A.FumarylacetoacetatehydrolaseSeveralmetabolicdisordersareassociatedwiththetyrosinecatabolicpathway.TheprobablemetabolicdefectintypeItyrosinemia(tyrosinosis)isatfumarylacetoacetatehydrolase.ItischaracterizedbybuildupoftoomuchoftheaminoacidtyrosineinthebloodandtissuesduetoaninabilitytometabolizeitThetherapyemploysadietlowintyrosineandphenylalanine.Untreatedacuteandchronictyrosinosisleadstodeathfromliverfailure.
631.Lesch?Nyhansyndromeiscausedby deficiencyofwhichenzyme? a)OrotatePhosphoribosyltransferase b)Uracilphosphoribosyltransferase c)QuinolinatePhosphoribosyltransferase d)Hypoxanthine-guaninephosphoribosyltransferase(HGPRT) CorrectAnswer-DAnswer:D.Hypoxanthine-guaninephosphoribosyltransferase(HGPRT)Theconditioniscalledksch-Nyhanslmdrome,inwhichthereiscompletedeficiencyofHGPRT.HGPRTdeficiencycausesdecreasedutilizationofPRPPinsalvagepathway.ThisresultsinincreasedproductionofpurinenucleotidefromPRPPviade-novopathway.Thediseaseischaracterizedbyhyperuricemia,goutyarthritis,urinarystones,neurologicalsymptoms.
632.Fishodorsyndromeiscausedby deficiencyofwhichenzyme? a)Fumarylacetoacetatehydrolase b)Methanemonooxygenase c)Monooxygenase3(FMO3) d)D-aminoacidoxidase CorrectAnswer-CAnswer:C.Monooxygenase3(FMO3)Trimethylaminuria,orfishodorsyndrome(FOS),isaconditioncharacterizedbythepresenceoftrimethylamine(TMA)--atertiaryaminewhoseodorisdescribedasresemblingthatofrottingfish--intheurine,sweat,andexpiredair.ThecauseofthesyndromeisrootedinthedysfunctionalmetabolismofTMA,whichisnormallyoxidizedbyflavinmonooxygenase3(FMO3)intonon-odoroustrimethylamine-N-oxide(TMAO).MostpatientswithFOSareeventuallydiagnosedwithprimarytrimethylaminuria,whichiscausedbyadeficiencyinFMO3thatisinheritedinanautosomalrecessivefashion.Thediagnosisismadeonthebasisoftheclinicalpresentationandurinalysis.UrinecanbeanalyzedfortheconcentrationofbothTMAandTMAO,andtheresultsmaybegivenasanoxidizingratiobasedontheformula-TMAO/(TMAO+TMA)x100%.Shortcoursesoforalneomycin,metronidazole,andamoxicillinhavebeenreportedtobeusefulinsomecases.
633.Galactosemiaisduetodeficiencyof whichenzymes a)Galactose-1-phosphateuridyltransferase b)HGPRT c)Galactokinase d)Epimerase CorrectAnswer-AAnswer:A.Galactose-1-phosphateuridyltransferaseGalactosaemia(Britishgalactosaemia)isararegeneticmetabolicdisorderthataffectsanindividual'sabilitytometabolizethesugargalactoseproperly.Galactosemiafollowsanautosomalrecessivemodeofinheritancethatconfersadeficiencyinanenzymeresponsibleforadequategalactosedegradation.
634.Whichofthefollowingismostabundant endproductoffattyacidsynthesis- a)Oleicacid b)Palmiticacid c)Arachidonicacid d)Glucose CorrectAnswer-BAnswer:B.PalmiticacidFattyacidaresynthesizedbyextramitochondrialsystem.Thissystemispresentinmanytissuesincludingliverkidneybrainlungmammaryglandandadiposetissues.AcetylCoAisimmediatesubstrate.Theendproductsofthissynthesisareusuallythesaturatedfattyacidspalmitateandstearatewiththelatterpredominating.
635.AboutDNApolymeraseIwhichoneis correct? a)Notrequiredinbacteria b)RepairanydamagewithDNA c)Involvedinokazakifragment d)ParticipateinDNAreplication CorrectAnswer-AAnswer:A.NotrequiredinbacteriaDNApolymeraseIparticipatesintheDNAreplicationofprokaryotes.FunctionofPolIismainlytorepairanydamagewithDNA,butitalsoservestoconnectokazakifragmentsdeletingRNAprimersandreplacingthestrandwithDNA.
636.Whatdoeschaperonesassistin? a)ProteinCleavage b)ProteinFolding c)ProteinDegradation d)ProteinModification CorrectAnswer-BAnswer:B.ProteinFoldingFoldingofProteinsinVivoIsPromotedbyChaperones
637.Fishyodouroccursduetodeficiencyof thisvitaminfromdiet- a)Biotin b)Thiamine c)Riboflavin d)Vit.A CorrectAnswer-CAnswer:C.RiboflavinVitaminB2orriboflavindeficiencycanbringaboutafishyodorinthebody.*Fish-odorsyndrome,alsocalledtrimethylaminuria,isararemetabolicdisordercausedbytheabsenceofenzynen-oxidase(AFlavincontainingmonooxygenase,3(FMO3).GenefortrimethylamineoxidasehasbeenmappedonchromosomeI(Iq23-q25).*Trimethylamineisnormallyproducedintheintestinefromthebreakdownofdietarycholineandtrimethylamineoxidebybacteria.*Eggyolkandliverarethemainsourcesofcholine,andfishisthemajorsourceoftrimethylamineoxide.*Trimethylamineisabsorbedandoxidizedintheliverbytrimethylamineoxidase(flavin-containingmonooxygenases)totrimethylamineoxide,whichisodorlessandexcretedintheurine.Deficiencyoftheenzymeresultsinmassiveexcretionoftrimethylamineinurine.*Consequently,tothesepatientssuchfoodsmaytastelikerottenfishandimportafishyodortotheirsalvia,sweatandurine.Treatment*Restrictionoffish,eggs,liverandothersourcesofcholine
(suchasnutsandgrains)inthedietsignificantlyreducetheodor.-Treatmentwithshortcourseoforalmetronidamle,neomycinorlactulosecausestemporaryreductioninthebodyodor.*RiboflavinsupplementcanbegiventoenhanceresidualFMO3activity.
638.VMAisexcretedinurineinwhich condition- a)Alkaptonuria b)Phenylketonuria c)Pheochromocytoma d)Diabeticketoacidosis CorrectAnswer-CAnswer:C.PheochromocytomaVMAistheendproductofcatabolismofcatecholamines.InpheochromocytomaandneuroblastomathereisexcessivesynthesisofcatecholamineswhichcausesenhancedsynthesisofVMAanditsexcretionintheurine.VMAistheurinaryproductofbothepinephrineandnorepinephrine.Itisagoodscreeningtestforpheochromocytoma,andisalsousedtodiagnoseandfollowupneuroblastomaandganglioneuroma.
639.InCystinuriaallofthefollowingamino- acidsreabsorptiondefectispresent,except a)Lysine b)Citrulline c)Arginine d)Ornithine CorrectAnswer-BAns.is'B'i.e.,CitrullineTypesofcystinuria*Type-I:Itishomozygouswithafullyrecessiveform.Thepatientexcretesalargequantityofcystine,ornithine,lysine,andarginine.GeneinvolvedisrBATonchromosome-2.*Type-II&III:Theseareheterozygousvariantsofincompletelyrecessiveforms.Theyexcretecystine,ornithine,lysine,andargininemorethannormalbutlessthanthehomozygousstate(Type-I).GeneinvolvedisSLC7A9onchromosome79.Cystinuria*BiochemicalDefect:Anautosomalrecessivedisorderthatresultsintheformationofadefectiveaminoacidtransporterintherenaltubuleandintestinalepithelialcells.*Pathophysiology:Theaminoacidtransporterisresponsiblefortransportingcystine,ornithine,lysine,andarginine.Defectivetubularreabsorptionoftheseaminoacidsinthekidneysresultsinincreasedcystineintheurine,whichcanprecipitateandcausekidneystones.*ClinicalManifestations:Cystinekidneystonespresentingwith
severe,intermittentflankpainandhematuria.*Labfindings:Increasedurinaryexcretionofcystine,ornithine,arginine,andlysineonurineaminoacidchromatography;hematuriaandcystinecrystals(hexagonal)onthecoolingofacidifiedurinesediment.*Imaging:RadiopaquekidneystonesonCTscan.Themostspecifictestisthecyanide?nitroprussidetest*Treatment:Low-methioninediet;increasedfluidintake;acetazolamidetoalkalinizetheurine.Ifthisfailsthenpatientsareusuallystartedonchelatingtherapywithpenicillamine.
640.FibrinopeptideAandfibrinopeptideB areacidicduetothepresenceofwhichaminoacidsinitsstructure- a)Serineandthreonine b)Glutamateandaspartate c)Histidineandlysine d)Glutamineandvaline CorrectAnswer-BAnswer:B.GlutamateandaspartateTheN-terminalAandBportionsoftheAandBchainsaretermedfibrinopeptideA(FPA)andfibrinopeptideB(FPB),respectively.Thesedomainsarehighlynegativelychargedasaresultofanabundanceofaspartateandglutamateresidues.Thenegativechargescontributetothesolubilityoffibrinogeninplasmaandimportantlyalsoservetopreventaggregationbycausingelectrostaticrepulsionbetweenfibrinogenmolecules.
641.HIAAinurinepresentin? a)Alkaptonuria b)Albinism c)Carcinoid d)Phenylketonuria CorrectAnswer-CAnswer:C.CarcinoidCarcinoidsyndromedevelopsinsomepeoplewithcarcinoidtumorsandischaracterizedbycutaneousflushing,abdominalcramps,anddiarrhea.Carcinoidtumouroccurthroughoutthegastrointestinaltract,mostcommonlyintheappendix,ileumandrectumindecreasingorderoffrequency.Right-sidedvalvularheartdiseasemaydevelopafterseveralyears.Thesyndromeresultsfromvasoactivesubstances(includingserotonin,bradykinin,histamine,prostaglandins,polypeptidehormones)secretedbythetumor,whichistypicallyametastaticintestinalcarcinoid.Diagnosisisclinicalandbydemonstratingincreasedurinary5-hydroxyindoleaceticacid(HIAA).Tumorlocalizationmayrequirearadionuclidescanorlaparotomy.Treatmentofsymptomsiswithsomatostatinoroctreotide,butsurgicalremovalisperformedwherepossible;chemotherapymaybeusedformalignanttumors.
642.Nitricoxideactsbyincreasing? a)BRCA1 b)BRCA2 c)Interleukin d)cGMP CorrectAnswer-DAnswer:D>cGMPNitricoxidediffusestothesurroundingsmoothmusclecells,increasingcGMP.Cyclicguanosinemonophosphate(cGMP)Cyclicnucleotidederivedfromguanosinetriphosphate(GTP).Function:cGMPactsasasecondmessengermuchlikecyclicAMP.Mechanismofaction:Activationofintracellularproteinkinasesinresponsetothebindingofmembrane-impermeablepeptidehormones.
643.Phenylketonuriaisduetodeficiencyof: a)Phenylalanine b)Phenylalaninehydroxylase(PAH) c)Phenylene d)Allofthese CorrectAnswer-BAnswerB.Phenylalaninehydroxylase(PAH)Abirthdefectthatcausesanaminoacidcalledphenylalaninetobuildupinthebody.PKUisanautosomalrecessivemetabolicgeneticdisorder.PKUischaracterizedbyhomozygousorcompoundheterozygousmutationsinthegeneforthehepaticenzymephenylalaninehydroxylase(PAH),renderingitnonfunctional.Thisenzymeisnecessarytometabolizetheaminoacidphenylalanine(Phe)totheaminoacidtyrosine(Tyr).WhenPAHactivityisreduced,phenylalanineaccumulatesandisconvertedintophenylpyruvate(alsoknownasphenylketone),whichcanbedetectedintheurine.ThePAHgeneislocatedonchromosome12inthebands12q22-q24.1.Morethan400disease-causingmutationshavebeenfoundinthePAHgene.
644.BywhichmethodforeignDNAis introducedintoacellbyavirusorviralvector? a)Transduction b)Transcription c)Lysogenicconversion d)Transformation CorrectAnswer-AAns.A.TransductionTransductionistheprocessbywhichforeignDNAisintroducedintoacellbyavirusorviralvector.AnexampleistheviraltransferofDNAfromonebacteriumtoanother.
645.Whichoneofthefollowingshows allostericinhibition? a)Malonicacid&succinate b)2,3BPG c)Aminoacidalanine&pyruvatekinase d)Citrate CorrectAnswer-BAnswer:B.2,3BPGNegativeallostericmodulation(alsoknownasallostericinhibition)occurswhenthebindingofoneliganddecreasestheaffinityforsubstrateatotheractivesites.Forexample,when2,3-BPGbindstoanallostericsiteonhemoglobin,theaffinityforoxygenofallsubunitsdecreases.
646.A4-year-oldboyofafirst-degree consanguineouscouplewasnotedbytheparentstohavedarkeningoftheurinetoanalmostblackcolorwhenitwasleftstanding.Hehasanormalsibling,andtherearenoothermedicalproblems.Growthanddevelopmenttodatearenormal.Whichofthefollowingismostlikelytobeelevatedinthispatient? a)Methylmalonate b)Homogentisate c)Phenylpyruvate d)-Ketoisovalerate CorrectAnswer-BAns:B.Homogentisate.*Alkaptonuriaisararemetabolicdiseaseinvolvingadeficiencyinhomogentisicacidoxidase,andthesubsequentaccumulationofhomogentisicacidintheurine,whichturnsdarkuponstanding.*Theelevationofmethylmalonate(duetomethylmalonylCoAmutasedeficiency),Phenylpyruvate(duetophenylalaninehydroxylasedeficiency),-ketoisovalerate(duetobranched-chain-ketoaciddehydrogenasedeficiency),Homocysteine(duetocystathionine-synthasedeficiency)
*Alloftheseareinconsistentwithahealthychildwithadarkeningoftheurine.*Reflippincott'sIllustratedreviews,5thedition,AminoAcidDegradationandSynthesis,Pg276.
647.Whichofthefollowingistrueabout differentstructuresofprotein? a)Secondarystructureisthethree-dimensionalstructureof protein b)Secondarystructureisstabilizedbydisulfidebonds c)Primary,secondaryandtertiarystructuresdestroyedduring denaturation d)Secondaryandtertiarystructuredependsonthesequenceof aminoacids CorrectAnswer-DAns:D.SecondaryandtertiarystructuredependsonthesequenceofaminoacidsExplanationProteinsarearrangedinanyofthefollowingfourstructuresviz:*PrimaryThesequenceofaminoacidsinaproteiniscalledtheprimarystructureoftheprotein.chain*Secondary-Thepolypeptidebackbonedoesnotassumearandomthree-dimensionalstructure,butinsteadgenerallyformsregulararrangementsofaminoacidsthatarelocatedneartoeachotherinthelinearsequence.The-helix,-sheet,and-bend(-turn)areexamplesofsecondarystructuresfrequentlyencounteredinproteins.*Tertiary-Itreferstothethree-dimensionalarrangementofapolypeptidechainthathasassumeditssecondarystructure.Disulfidebonds
betweencysteineresiduesmaystabilizethetertiarystructure.Proteindenaturationresultsintheunfoldinganddisorganizationoftheprotein'ssecondaryandtertiarystructures,whicharenotaccompaniedbyhydrolysisofpeptidebonds*Quaternary-Thequaternarystructurerequiresmorethanonepolypeptidechain.Thesechainsassociatethroughnoncovalentinteractions.Reflippincott'sIllustratedreviews,5thedition,StructureofProtein,Pg13
648.Theinsulinglucagonratiodecreased. Theenzymeisactiveatthistime? a)Glucokinase b)Hexokinase c)Phosphofructokinase d)Glucose6phosphatase CorrectAnswer-DAns.D.Glucose6phosphataseExplanationLowinsulin:glucagonratio(IGR)stimulatesmobilizationofstorednutrients,increasesglycogenolysisandgluconeogenesis,andpromotesthebreakdownofadiposetissueintofreefattyacidsandglycerol.DecreasesInsulin/glucagonratioshowsthefastingstage.Glucokinase,Hexokinase,andphosphofructokinaseareglycolytic.Onlygluconeogenicisglucose6phosphatase.Ref-https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4801814
649.Ochronosisisduetotheaccumulation of? a)Homogentisicacid b)Homogentisicacid c)Xanthurenate d)Glyoxylate CorrectAnswer-AAns:A.HomogentisicacidAlkaptonuriaisanautosomalrecessiveconditionduetothedeficiencyofhomogentisate1,2dioxidase.Thisresultsintheexcretionofhomogentisicacidinurine.iscompatiblewithafairlynormallife.Theonlyabnormalityistheblackeningofurineonstanding.Homogentisicacidisoxidizedbypolyphenoloxidasetobenzoquinoneacetate.Itisthenpolymerizedtoblackcoloredalkaptonbodies.Bythe3rdor4thdecadeoflife,thepatientmaydevelopochronosis(depositionofalkaptonbodiesinintervertebraldiscs,cartilagesofnose,pinnaoftheear).Blackpigmentsaredepositedovertheconnectivetissuesincludingjointcavitiestoproducearthritis.Nospecifictreatmentisrequired.Butminimalproteinintakewithphenylalaninelessthan500mg/dayisrecommended.Ref-DMVasudevan-Textbookofbiochemistryformedicalstudents,6thedn,AromaticAminoAcids,andAminoAcidurias,pg208.
650.Bilirubininserumcanbemeasuredby a)VandenBerghreaction b)Ehrlich'sReaction c)Schlesinger'sReaction d)Fouchet'sReaction CorrectAnswer-AAns:A.VandenBerghreactionBilirubinismostcommonlydeterminedbythevandenBerghreaction,inwhichdiazotizedsulfanilicacidreactswithbilirubintoformredazodipyrrolesThesearemeasuredcolorimetrically.Inaqueoussolution,thewater-soluble,conjugatedbilirubinreactsrapidlywiththereagent(withinoneminute),andissaidtobe"direct-reacting."Theunconjugatedbilirubin,whichismuchlesssolubleinaqueoussolution,reactsmoreslowly.However,whenthereactioniscarriedoutinmethanol,bothconjugatedandunconjugatedbilirubinaresolubleandreactwiththereagent,providingthetotalbilirubinvalue.The"indirect-reacting"bilirubin,whichcorrespondstotheunconjugatedbilirubin,isobtainedbysubtractingthedirect-reactingbilirubinfromthetotalbilirubinNote:Innormalplasma,onlyabout4%ofthetotalbilirubinisconjugatedordirect-reacting,becausemostaresecretedintobile.Ref-Lippincott'sIllustratedreviews,5thedition,Conversionofaminoacidsinspecializedproducts,Pg285.
651.IfasampleofDNAifadenineis28% whatwillbetheamountofCytosinepresent a)23% b)25% c)46% d)22% CorrectAnswer-DAns:D.22%ThebasesofonestrandofDNAarepairedwiththebasesofthesecondstrandsothatadenineisalwayspairedwiththymineandcytosineisalwayspairedwithguanine.Therefore,onepolynucleotidechainoftheDNAdoublehelixisalwaysthecomplementoftheother.Giventhesequenceofbasesononechain,thesequenceofbasesonthecomplementarychaincanbedetermined.Note:ThespecificbasepairinginDNAleadstotheChargaffRule:InanysampleofdsDNA,theamountofadenineequalstheamountofthymine,theamountofguanineequalstheamountofcytosine,andthetotalamountofpurinesequalsthetotalamountofpyrimidines.Thebasepairsareheldtogetherbyhydrogenbonds:twobetweenAandTandthreebetweenGandC(Figure29.5).Thesehydrogenbonds,plusthehydrophobicinteractionsbetweenthestackedbases,stabilizethestructureofthedoublehelix.Ref-lippincott'sIllustratedreviews,5thedition,thestructureofDNA,pg397
652.Whichofthefollowingvitaminathigher dosescausescystoidmacularedema- a)VitA b)VitD c)VitE d)Niacin CorrectAnswer-DAns:D.NiacinCystoidmacularedema(CME)isaconditionthatinvolvesthemacula,causingpainlessvisionloss.Niacin(nicotinicacid,vitaminB3,vitaminPP),onecomponentofthedietarysupplementtakenbythepatient,isavitaminpreparationusuallyusedforthetreatmentoflipiddisordersFraunfelderetal.reportedthat3gormoreperdayofnicotinicacidcouldcausemanyocularsideeffectssuchasblurredvision,eyelidedema,toxicamblyopia,proptosis,lossofeyelashesoreyebrow,superficialpunctatekeratitis,andcystoidmacularedema,whichrepresentsthemostseriousocularcomplications.AlltheseadverseeffectsarereversiblewithdiscontinuationofniacintherapyRef-CaseReportsinOphthalmologicalMedicine,Volume2013,ArticleID713061,5page
653.TruestatementregardingHuntington's choreais a)Thereisalossoffunctiontypeofmutation b)Itisanautosomalrecessive c)Itisatrinucleotiderepeatexpansiontypeofdisorder d)IncreasednumberofCAArepeats CorrectAnswer-CAns:C.ItisatrinucleotiderepeatexpansiontypeofdisorderHuntington'schoreaisanautosomaldominantdisorderwithanincreasednumberofCAGrepeats.Clinicallymanifestedasinvoluntaryjerkymovements,mooddisturbancesandfinallyseveredementia.Ref-Langebiochemistryandgeneticsflashcards,Huntington'sdisease,pg161
654.AdditionofwhichAminoAcidwill increaseUVabsorption a)Tryptophan b)Leucine c)Proline d)Arginine CorrectAnswer-AAns:A.TryptophanAminoAcidAbsorbUVLightAminoAcidsthatabsorb250-290nm(Maximumat280nm)UVlightaretryptophan,phenylalanine,tyrosine.ThemaximumabsorptionofUVlightisbytryptophan.Asitabsorbsultravioletlightabouttentimesmoreefficientlythanphenylalanineortyrosine,tryptophanmakesthemajorcontributiontotheabilityofmostproteinstoabsorblightintheregionof280nm.TryptophanandtyrosineabsorbUVatapproximately280nrn.UVabsorptionspectroscopyisutilizedtomeasureproteinconcentration.TheabsorptionspectrumofaproteinintheUVwavelengthrangeistheresultofabsorptionoflightbythearomaticaminoacids(250-320nm),thedisulfidebonds(250-300nm)andthecarbonylgroupofthepeptidebond(190-210).RememberAromaticAminoAcidsabsorbUVLightsAminoacidsarecolourlessbecausetheydonotabsorbvisiblelight.Ref-Rebeccajames-selfassessmentandreviewofbiochemistry,3rdedn,Chemistry,andMetabolismofAminoAcids,Pg7
655.V-RichestsourceofvitaminB12? a)Meat b)Greenleafyvegetables c)Cornoil d)Sunfloweroil CorrectAnswer-AAns:A.Meat*VitaminB12isnaturallyfoundinanimalproducts,includingfish,meat,poultry,eggs,milk,andmilkproducts.*Synonymsarecobalamin,extrinsicfactor(EF)ofCastleandantiperniciousanemiafactor.VitaminB12iswater-soluble,heatstableandredincolor.Itissatisfiedbyanyofthefollowinggroups:cyanide,hydroxyl,adenosylormethyl.*Cyanocobalamin-Oralpreparationsareinthisform.*Hydroxycobalamin-Injectablepreparationsareinthisform.*Adenosylcobalamin-Thisisthemajorstorageform,seenintheliver.*Methylcobalamin-Thisisthemajorformseeninbloodcirculationaswellasinthecytoplasmofcells.*VitaminB12isgenerallynotpresentinplantfoods,butfortifiedbreakfastcerealsareareadilyavailablesourceofvitaminB12withhighbioavailabilityforvegetarians.*RichsourceofvitaminB12-Beef,liver,andchicken.-Fishandshellfishsuchastrout,salmon,tunafish,andclams.-Fortifiedbreakfastcereal.-Low-fatmilk,yogurt,andcheese.-Eggs.
Ref-DMVasudevan-Textbookofbiochemistryformedicalstudents,6thedn,Nutrition,pg404.
656.Whichaminoacidisusedtosynthesize Nitricoxide? a)Glycine b)Arginine c)Tyrosine d)Threonine CorrectAnswer-BAns:B.ArginineNitricoxideisformedfromargininebytheenzymenitricoxidesynthase(NOS).Itcontainsheme,FAD,FMN,NADPH,andtetrahydrobiopterin.Nitricoxidehasaveryshorthalf-life(3-4seconds).NOcombineswithoxygentoformNO2.Thesenitritesareexcretedthroughurine.Reactingwithhemoglobin,NOisconvertedtoNO3;andnitratesarealsoexcretedintheurine.TheverylowquantityofNOisexpelledthroughthelung.Arginineisahighlybasic,semi-essentialaminoacid.Itisglucogenicinnature.
657.TrueAboutNoncompetitiveantagonist- a)Kmremainssame,Vmaxdecreases b)Kmremainssame,Vmaxdecreases c)Kmdecreases,Vmaxincreases d)Kmincreases,Vmaxincreases CorrectAnswer-AAns:A.Kmremainssame,VmaxdecreasesNoncompetitiveinhibitionoccurswhentheinhibitorandsubstratebindatdifferentsitesontheenzyme.ThenoncompetitiveinhibitorcanbindeitherthefreeenzymeortheEScomplex,therebypreventingthereactionfromoccurring.EffectonVmax:Noncompetitiveinhibitioncannotbeovercomebyincreasingtheconcentrationofthesubstrate.Thus,noncompetitiveinhibitorsdecreasetheapparentVmaxofthereaction.EffectonKm:Noncompetitiveinhibitorsdonotinterferewiththebindingofsubstratetoenzyme.Thus,theenzymeshowsthesameKminthepresenceorabsenceofthenon-competitiveinhibitor.EffectonLineweaver-Burkplot:Noncompetitiveinhibitionisreadilydifferentiatedfromcompetitiveinhibitionbyplotting1/voversus1/[S]andnotingthattheapparentVmaxdecreasesinthepresenceofanon-competitiveinhibitor,whereasKmisunchangedRef-lippincott'sIllustratedreviews,5thedition,InhibitionofEnzymeActivity,pg61.
658.Wernersyndromeassociatedwith prematureagingiscausedduetoadefectinwhichofthefollowing? a)Telomerase b)Caspase c)DNAtopoisomerase d)DNAhelicase CorrectAnswer-DAns:D.DNAhelicaseWernersyndromeisahumanautosomalrecessivedisorderthatdisplayssymptomsofprematureaging,includingearlygrayingandthinningofhair,wrinklingandulcerationofskin,atherosclerosis,osteoporosis,andcataracts.Inaddition,Wernersyndromepatientsexhibitanincreasedincidenceofdiabetesmellitustype2,hypertension,andarehighlydisposedtotheemergenceofbenignandmalignantneoplasms.WernersyndromecausedbymutationoftheWRNgene,amemberoftheRecQDNAhelicasefamily.Ref-https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3237395/
659.Whichofthefollowingdietaryfiberis insolubleinwater? a)Pectin b)Lignin c)Hemicellulose d)Cellulose CorrectAnswer-BAns:B.LigninTheunavailableorindigestiblecarbohydratesinthedietarecalleddietaryfiber.Dietaryfiberisnecessarytomaintainthenormalmotilityofthegastrointestinaltract.Theyarechiefly-Cellulose-Retainswaterinfeces,promotesperistalsis,increasesbowelactionLignin-Antioxidant,increasesbileacidexcretion,hypocholesterolemic.Pectins-PartiallyAbsorbwater,slowsesterifiedgastricemptying,bindsbileacids,increasestheirexcretionHemi-cellulose-Retainswaterinfeces,cellulose,increasesbileacidanduronicacidexcretion.Ref-DMVasudevan-Textbookofbiochemistryformedicalstudents,6thedn,EnergyMetabolismandNutrition.Pg435.
660.AccordingtoNCEP-ATPIII,whichamong thefollowinghavenotbeenincludedinmetabolicsyndrome? a)HighLDL b)Hypertriglyceridemia c)CentralObesity d)Hypertension CorrectAnswer-AAnswer-A.HighLDLMetabolicsyndromereferstotheco-occurrenceofseveralknowncardiovascularriskfactors,includinginsulinresistance,obesity,atherogenicdyslipidemia,andhypertension.Theseconditionsareinterrelatedandshareunderlyingmediators,mechanisms,andpathways.CriteriafortheDiagnosisofMetabolicSyndromeElevatedwaistcircumference:(Formen>90cmandforwomen,>80cm).Elevatedtriglycerides:>150mg/dLReducedHDL("good")cholesterol:Formen,<40mg/dL;forwomen,<50mg/dLElevatedbloodpressure:>130/85mmHgElevatedfastingglucose:>100mg/dLInsulinresistance(hyperinsulinemia)Additionalparametersinclude:coagulationabnormalities,hyperuricemia,microalbuminurianon-alcoholicsteatohepatitis(NASH)andincreasedCRP.Diagnosisismade,ifany3outofthe5criteriagivenabove.
Ref-DMVasudevan-Textbookofbiochemistryformedicalstudents,6thedn,Clinical,andAppliedBiochemistry,pg286
661.Whichofthefollowingisthebasisfor theintestine-specificexpressionofapoproteinB-48? a)DNArearrangementandloss b)DNArearrangementandloss c)RNAalternativesplicing d)RNAediting CorrectAnswer-DAns:D.RNAediting.TheproductionofapoB-48intheintestineandapoB-100inliveristheresultofRNAeditingintheintestine,whereasensecodonischangedtoanonsensecodonbypost-transcriptionaldeaminationofCtoU.DNArearrangementandtransposition,aswellasRNAinterferenceandalternatesplicing,doaltergeneexpression,butarenotthebasisofapoB-48tissue-specificproduction.Reference-Lippincott'sIllustratedReviews:Biochemistry,5thedition,RegulationofGeneExpression,Pg464.
This post was last modified on 23 November 2021