Download MBBS Cell Cycle Lecture PPT

RNA.

? RNA is polymer of ribonucleotides.

--- Content provided by FirstRanker.com ---

? Linked together by 3'-5' phosphodiester bond.
? Function of RNA-
? Protein synthesis.
? Genetic material.
? Ribozymes.

--- Content provided by FirstRanker.com ---

?
TYPES OF RNA.

? Messenger RNA

--- Content provided by FirstRanker.com ---

mRNA

? m RNA

? Transfer RNA

--- Content provided by FirstRanker.com ---

t RNA

? T RNA

--- Content provided by FirstRanker.com ---

? Ribosomal RNA

r RNA

? R RNA

--- Content provided by FirstRanker.com ---

GENE REGULATION.

? Gene regulation refers to the mechanism that act to induce or

repress the expression of a gene.

--- Content provided by FirstRanker.com ---

Level of Gene control.

? Gene on DNA
? |
? - -Transcriptional control

--- Content provided by FirstRanker.com ---

?
? Primary transcript
?
? ( RNA processing control)

--- Content provided by FirstRanker.com ---

m RNA

( RNA transport control )

| -- Translation control.

--- Content provided by FirstRanker.com ---

Protein


TYPES OF RNA.

--- Content provided by FirstRanker.com ---

m ? RNA- messenger.

Translation.

--- Content provided by FirstRanker.com ---

r-RNA- ribosomal

Protein synthesis.

t- RNA- transfer

--- Content provided by FirstRanker.com ---

translation

Sn-RNA-- small nuclear

--- Content provided by FirstRanker.com ---

m RNA processing poly a addition

Sno-RNA---small nucleolar

r- RNA processing/ maturation,

--- Content provided by FirstRanker.com ---

methylation.

Regulatory RNA---siRNA and miRNA

--- Content provided by FirstRanker.com ---

Regulation of transcription and translation.
Regulatory RNAs.

? Small nuclear RNA

--- Content provided by FirstRanker.com ---

Sn RNA

? Sn RNA

? micro

--- Content provided by FirstRanker.com ---

mi RNA

? RNA

--- Content provided by FirstRanker.com ---

? Small interferring

Si RNA

? RNA

--- Content provided by FirstRanker.com ---

REGULATORY RNA.

? Inhibition of gene expression.

siRNA

--- Content provided by FirstRanker.com ---

? Inhibition of gene expression.

mi RNA

--- Content provided by FirstRanker.com ---

? Tumour suppression and oncogenes.

? Primary transcript RNA.

Nascent RNA ? Needs to be processed like--capping, RNA splicing.

--- Content provided by FirstRanker.com ---

PHASE OF CELL CYCLE

? G1---- (Gap-1)--Phase.
? S-------Synthetic phase.
? G2- --- Gap-2 Phase.

--- Content provided by FirstRanker.com ---

? M-------Mitotic phase.
? G1, S, and G2-----Interphase--cell prepare to divide.
? M phase---Both DNA and cytoplaslm divide to produce two

daughter cells.

--- Content provided by FirstRanker.com ---

PHASE OF CELL CYCLE.
INTERPHASE.
INTERPHASE- G1 PHASE.

? 1st growth stage after cell division.

--- Content provided by FirstRanker.com ---

? Cells matures by making more cytoplasm and organelles.

? Cells carries on its normal metabolic activity.
? S-STAGE-
? synthesis stage.

--- Content provided by FirstRanker.com ---

? DNA is copied or replicated.
INTERPHASE --G2 - stage

? 2nd growth stage.
? Occurs after DNA has copied.

--- Content provided by FirstRanker.com ---

? All cell structure needed for division are made.(eg-centriole).
? Both organelles and proteins are synthesized.
? DNA replicates, centriole if present replicate.
? cell prepares for division.
MITOSIS.

--- Content provided by FirstRanker.com ---

MITOSIS.

? Division of nucleus also called karyokinesis.
? Has four stages.
? Four mitotic stages are--

--- Content provided by FirstRanker.com ---

? Prophase.
? Metaphase.
? Anaphase.
? Telophase.
?

--- Content provided by FirstRanker.com ---

Early prophase.

? Chromatin in nucleus condenses to form visible chromosome.
? Mitotic spindle forms.
? Late Prophase? nuclear membrane and nucleolus

--- Content provided by FirstRanker.com ---

are broken down.

? Chromosome condenses and clearly visible.
? Spindle fibre called kinetochore attach to the centromere of

--- Content provided by FirstRanker.com ---

each chromosome.

? Spindle finishes forming between the poles of the cell.
?

--- Content provided by FirstRanker.com ---

METAPHASE.

? Chromosomes, attached to the kinetochores fibre, move to

the centre of the cell.

--- Content provided by FirstRanker.com ---

? Chromosomes now lined up at the equator.

ANAPHASE --

--- Content provided by FirstRanker.com ---

? occurs rapidly.
? Chromatids are pulled apart to opposite poles

by kinetochores fibres.

--- Content provided by FirstRanker.com ---

?

TELOPHASE.

? Sister chromatids at opposite poles.

--- Content provided by FirstRanker.com ---

? Spindle disasembles.
? Nuclear envelope forms.
? Nucleolus reappears.
? Cytokinesis occurs.
? Chromosome reappear as chromatin.

--- Content provided by FirstRanker.com ---

CYTOKINESIS.

? Means division of cytoplasm.
? Division of cell into two identical half called daughter cells .

--- Content provided by FirstRanker.com ---

? Daughter cells of mitosis have same number of chromosomes

that of parent cell.

? Must grow in size to become mature cells.( G1 of Interphase)

--- Content provided by FirstRanker.com ---

METAPHASE.
ANAPHASE.
TELOPHASE.
PHASE OF CELL CYCLE AND REGULATION.

--- Content provided by FirstRanker.com ---

Cyclin D ,CDK-4

G2-

G1

--- Content provided by FirstRanker.com ---

cdk1

S ?cyclin

--- Content provided by FirstRanker.com ---

E,cdk2
ROLE OF CDK-1 COMLEX IN G2 CHECK POINT

REGULATION.

--- Content provided by FirstRanker.com ---

? CYCLIN B--CDK-P ---INACTIVE
? <- Active protein kinase <-

DNA strand break.

--- Content provided by FirstRanker.com ---

? |
? CYCLIN ?B CDK-1 ---ACTIVE
? |

? Phosphorylation of several protein.

--- Content provided by FirstRanker.com ---

? |
? Bipolar spinle formation -----MITOSIS.
Cyclin and cdk molecule.
FIVE PHAGES OF THE CELL CYCLE.

--- Content provided by FirstRanker.com ---

? G1--Primary growth phase.
? S---synthesis, DNA replicated.
? G2--secondary growth phase.
? Collectively these 3 stages are called interphase.
? M--mitosis.

--- Content provided by FirstRanker.com ---

? C--cytokinesis.
CELL CYCLE REGULATION.

? Why cell cycle cycle regulation-------
? cell division is expensive process.

--- Content provided by FirstRanker.com ---

? Maintain integrity of genome.
? Proper cellular homeostasis.
? Prevent onset of mutation.
KEY REGULATOR.

--- Content provided by FirstRanker.com ---

Cdk/cyclin dependent protein,catalytic protein.

? Cyclin, regulatory protein.

Apart from these , two other important regulator....

--- Content provided by FirstRanker.com ---

? (Rb protein and p53 protein.)-Tumours suppressor protein.
Oncogenes also disrupt cell cycle.

? P53 is a tumor suppressor gene ?

--- Content provided by FirstRanker.com ---

? p53 gene produces a protein with a

molecule mass of 53kDa.This protein suppresses the tumour

formation. it arrest the cell cycle at G2/M check point.

--- Content provided by FirstRanker.com ---

Mutation in p53 gene are found in 50% of all cancer.

? It distrupts cell cycle both at G1/S and G2/M check point by

--- Content provided by FirstRanker.com ---

coding for a CDK inhibitors called p21 which binds to several

cyclin CDK comlexes influencing the cell cycle.
BCL2 GENE.

--- Content provided by FirstRanker.com ---

? BCL2 gene associated with beta ? cell lymphoma appears to

induce cyclin D gene. Excess cyclin D expression could result in

unrestained cell division leading to cancer.

--- Content provided by FirstRanker.com ---

? CDK INHIBITORS----------
? CDK are inhibited by CDK inhibitors

which are produced in response to signal like DNA damage.

--- Content provided by FirstRanker.com ---

These inhibitor lead to arrest of cell cycle.
CYCLINS.

? They named because they undergo a cycle of synthesis of

--- Content provided by FirstRanker.com ---

degradation in each cycle.

? It is a regulatory protein of cell cycle and shows continuous

--- Content provided by FirstRanker.com ---

rise and fall during the various stages of cell cycle.

? Synthesis of cyclins proteins begins during G1 phase and they

increases their concentration till Metaphases but in anaphase

--- Content provided by FirstRanker.com ---

they are degraded by the actvated by the actIvity of APC.
FOUR CLASSES OF CYCLINS.

? G1 CYCLINS---

--- Content provided by FirstRanker.com ---

? Help to promote passes through " start" .
? G1/S CYCLINS----
? Bind to Cdks at the end of G1 and commit cell to

DNA replication.

--- Content provided by FirstRanker.com ---

? S-CYCLINS----
? Bind Cdks durindg S phase cand are required for

initiator of DNA replication.

--- Content provided by FirstRanker.com ---

? M CYCLINS --Promote the event of mitosis.
Cyclin.

Cyclin is the important key regulator of cell cycle.

--- Content provided by FirstRanker.com ---

? Cyclin...........

Also regulate the activity of cdk.(cyclin dependent kinase.)

--- Content provided by FirstRanker.com ---

? Regulator of both cell cycle and cdk.
CYCLIN DEPENDENT KINASE.

? Progression of cell cycle is controlled by a conserved

--- Content provided by FirstRanker.com ---

set of protein called --

KINASE

? KINASE.

--- Content provided by FirstRanker.com ---

? Regulate the progression of cell cycle in association

with another group of protein called as--

--- Content provided by FirstRanker.com ---

CDK

? Cyclins.

? Concentration of cyclins fluctuates throughout the

--- Content provided by FirstRanker.com ---

cell cycle

CYCLINS

--- Content provided by FirstRanker.com ---

? Cyclins.
DIFFERENT TYPES OF Cdk.

? G2 to M phase.

--- Content provided by FirstRanker.com ---

Cdk1 ? G2 to M

? G1 to S.

Cdk2 ? G1 to S phase.

--- Content provided by FirstRanker.com ---

? G1 to S.
? Gap 1 to Synthetic phase.

cdk4

--- Content provided by FirstRanker.com ---

Cdk 20--Metaphase to Anaphase....
THREE MAIN TRANSITION CHECK POINTS IN

CELL CYCLE.

--- Content provided by FirstRanker.com ---

G1 TO S.

G2 TO M.

--- Content provided by FirstRanker.com ---

METAPHASE

TO ANAPHASE.
G1 CHECK POINT.

--- Content provided by FirstRanker.com ---

Checks conditions are favouring

for cell division.

Checks for genomic DNA damage

--- Content provided by FirstRanker.com ---

at G1,adequate energy reserves,

DNA damage.

--- Content provided by FirstRanker.com ---

Synthesis of G1 cyclins must

reach specific level to cross the

start point.

--- Content provided by FirstRanker.com ---

Rb protein.(Retinoblastoma protein).

? Classic tumour suoppressor.
? Its product called Rb protein prevents the cell to migrate from

--- Content provided by FirstRanker.com ---

G1 to S Phase.

? Master regulator of biological pathway like---
? Cell Growth, cell cycle checkpoints, differentiation,

--- Content provided by FirstRanker.com ---

replication, genomic stability and apoptosis.
P53 protein.

(GUARDIAN OF GENOME.)

--- Content provided by FirstRanker.com ---

? Tumour suppressor gene.

P53 PROTEIN.

? P53.

--- Content provided by FirstRanker.com ---

? Preventing tumour developement

P53

--- Content provided by FirstRanker.com ---

? p53

? Inhibit over expression of cell.

P53

--- Content provided by FirstRanker.com ---

? Regulate the cell cycle.