30_DNA Damage & Cell Cycle Checkpoints Flashcards Preview

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Flashcards in 30_DNA Damage & Cell Cycle Checkpoints Deck (17)
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1
Q

What are the cell’s three reactions to DNA damage?

A

1) repair
2) activate checkpoint, arrest cell cycle
3) apoptosis

2
Q

The cell cycle halts if two critical events are incomplete; what are they?

A

DNA replication in S phase

Chromosome alignment during M phase

3
Q

What is the inheritance pattern of ataxia-telangiectasia?

A

recessive

4
Q

What type of radiation are patients with AT sensitive to?

A

ionizing radiation (causing dsDNA breaks)

5
Q

Which gene is mutated in AT patients?

A

ATM

6
Q

What are ATM and ATR activated by?

A

ATM: dsDNA breaks
ATR: ssDNA breaks

7
Q

What type of DNA damage does UV radiation induce?

A

ss-DNA breaks

8
Q

Which type of radiation induces double-stranded DNA breaks?

A

ionizing radiation

9
Q

Which checkpoint kinases do ATM and ATR activate?

A

ATM: Chk2
ATR: Chk1

10
Q

Which protein is dubbed the “guardian of the genome”? At which stage does it arrest the cell cycle?

A

p53

G1 => S

11
Q

Cdc25 is a (kinase/phosphatase).

A

phosphatase

12
Q

What effect does phosphorylation have on cdc25?

A

results in its shuttling to the cytoplasm. CDK complex remains inactive, and cell cycle is arrested at G2-M.

13
Q

Is p53 stable in its phosphorylated or dephosphorylated form?

A

phosphorylated

14
Q

As a result of phosphorylation of p53, what genes are transcribed more?

A

p21 - CDI & Bax

15
Q

What does p21 CDI inhibit?

A

G1 and S CDKs

16
Q

What is the consequence of Bax upregulation?

A

apoptosis

17
Q

Which effector is involved in arresting the cell cycle at the G2-M checkpoint?

A

cdc25