Intro to cell cycle? Flashcards

1
Q

What are the two main parts of cell cycle?

A

Interphase and mitosis

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2
Q

What is the interphase stage? And what phases is it made up of? What is the purpose of each stage?

A

It’s when chromosomes prepare for duplication and duplicate. G1,S,G2.
G1-growth and metabolic roles
S-chromosome duplication
growth and prepration for mitosis

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3
Q

What is the fastest stage in the cell cycle?

A

Mitosis

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4
Q

What are the periods found in mitosis and what is the purpose of each?

A

Prophase-The chromosomes will condense
Metaphase-The chromosomes will attach to spindles and move toward the center of the cell
Anaphase- Sister chromatids will seperate
Telophase- The chromosomes will decondense

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5
Q

What is cytokinesis?

A

Physical seperation of divided cells

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6
Q

When are cell in G0? What is G0?

A

The resting phase

Differntiated or deprived of nutirents

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7
Q

What is the purpose of checkponts and control in cell cycle?

A

To ensure that the cells divided with no errors and they are diploid

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8
Q

Who was awarded noble prize for discovering control mechanism in cell cycle? What are the conclusions of cell fusion experiments?

A

Hartwell, nurse, Hunt.
MPF contains factors that can induce chromosome condensation at any cell stage
But SPF has factors that only induce replication in G1 phase

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9
Q

What proteins are involved in controlling cell cycle?

A

CDK and cyclins

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10
Q

What period are cells sensitive to mitogens?

A

G1

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11
Q

How many cyclins, CDK, CDKI were identified in mammals?

A

13 cyclins, 8CDK,7CDKI

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12
Q

T/F

Cyclins and CDK the only proteins that change in the cell cycle

A

False

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13
Q

T/F

Cyclin D is cell type specific

A

True

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14
Q

How are cyclins turned off?

A

By ubiquination and degradation

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15
Q

What genes transcribe Cyclin D? And what CDK do they bind to? What stage of the cell cycle are they expressed?

A

AP-1, c-myc, NFKB.
cdk4,2,6,5
Early stages G0,G1, peaks near the end of G1

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16
Q

What do cyclinD/CDK4 act on and what does it induce? What is it’s effect in the cell cycle?

A

RB, it phosphorylates RB which releases it from E2 phase, it induces th eprogression of the cell to S phase and through the restriction point

17
Q

When is cyclinE/CDK 2 expressed? And what is it’s effect in the cell cycle?

A

At the end of G1 and degrades 1/2 way through Sphase

18
Q

T/F

cyclinE/CDK 2 has histone kinase activity

A

T

19
Q

When is cyclin A expressed and when does it degrade? What does it bind to? Why is it important in the cell cycle?

A

At the end of Sp phase, at anaphase
CDK2,1
Initiation and progression of replication

20
Q

When is cyclin B expressed and when does it degrade? What does it bind to? Why is it important in the cell cycle?

A

end of S phase, end of anaphase
binds to CDK
Needed for cell to enter mitosis

21
Q

Give an example of phosphatase? When does it accumulate?

A

CDC25, M phase

22
Q

What role does phosphorylation play in CDK and cyclin during cell cycle

A

It activates and inactivates activity and it’s important for nuclear localization

23
Q

What is CDC 13 and what is it’s role?

A

It’s a type of cyclin B important in cell cycle control prevents the cell from moving from g2 to m phase

24
Q

What brings the cyclins to their CDKS?

A

chaperone complex

25
Q

What is P21 and how does it work? What is it used for normally?

A

P21- is a tumour suppressor that inhibits all CDK/cyclin complexes and DNA polymerase.
It is expressed durong differentiation

26
Q

What are other cyclin kinase inhibitors?

A

P14, P15,P16, P18.

27
Q

What is ARF and how does it effect P53? What activates ARF?

A

ARF is a tumour suppressor that activates P53 and P16 by inhibiting MDM2. Overexpression of c-myc and E2F

28
Q

What does MDM2 do?

A

It ubiquitinates P53 and exports it out of the nuclease for degradation

29
Q

Explain how P27 is induced and works and how it’s inhibited?

A

P27 would be induced by cell-cell contact and TGF-B
iT inhibits the cyclin E,D ,A complexes which inhibits RB phosphorylation. It is associated with migration
It is inhibited by AKT which phosphorylates it and it’ll be exported.

30
Q

What are ways to target cancers using cell cycle proteins?

A

Chemotherapeutic- kinase inhibitor
Adeno reteroviral vector that overexpresses any of cyclin kinase inhibitor such as p21
antisense against cyclin D

31
Q

What activates P53 molecularly?

A

ATM and ARF

32
Q

What regulates the g2/m transition?

A

CHK1 phosphorylates CDC25 which will keep cdc2 in it’s inactive form

33
Q

What does P53 produce when activated?

A

p21 and GADD45.

34
Q

What does GADD45 do? What does P21 do?

A

It binds to PCNA and repairs DNA

While p21 inhibits PCNA induces apoptosis or a pause in the cell cycle progression

35
Q

What regulates G1/S transition?

A

P53