9.9 Cell Cycle

Question 1

what does the cell do in G1 phase?

Answer 1

it gathers nutrients and energy. Lives and prepares

Question 2

what does the cell do in the S phase?

Answer 2

it commits to duplication and division. DNA/organelle replication

Question 3

what does the cell do in the G2 phase?

Answer 3

it checks and fixes DNA

DNA repair

Question 4

what does the cell do in M phase?

Answer 4

divide

Question 5

what are the three locations of the major cell cycle checkpoints?

Answer 5

G1/S transition
G2/M transition
metaphase/anaphase transition

Question 6

what causes transition between G1 to S phase?

Answer 6

increase in CycE-Cdk2 levels

Question 7

CycE-Cdk2 increase levels of what other cyclin?

Answer 7

CycA

Question 8

CycA degrades _____ (what cyclin)

Answer 8

CycE

Question 9

what does CycA do?

Answer 9

it induces DNA replication in S phase

Question 10

CycB (inactivated) increases and is maximal before ____ phase. It degrades Cyc___.

Answer 10

M phase

CycA

Question 11

CyB is regulated by phosphorylation by two enzymes: ______ and ______. Which inhibits and which activates?

Answer 11

CAK - activated

Wee - inhibits

Question 12

to activate CycB, the inhibitory phosphate needs to be removed by _______.

Answer 12

Cdc25

Question 13

what activated Cdc25 to dephosporylate the inhibitory phosphate on CycB?

Answer 13

complete and accurate DNA replication

Question 14

once the inactivating inhibitory phosphate is removed from CycB, what phase transition can happen?

Answer 14

G2 –> M phase

Question 15

what is the “anaphase wait” signal?

Answer 15

all kinetochores are attached with a microtubule and ready to split

Question 16

Wee1 inhibits what?

Answer 16

CycB-Cdk1

Question 17

once anaphase is reached, what is expressed? What do they do?

Answer 17

APCs are expressed, they degrade CycB and CycA

Question 18

what regulates CDKs? (4)

Answer 18

1. cyclin changes (either increase in expression through TFs or degradation such as APCs)
2. Phosphorylation (Wee, CAK)
3. CKIs (CDK inhibitors) in G1

Question 19

what are CKIs? (p21, p27, etc)

Answer 19

inhibitors of CDK

Question 20

what is pRB? Is it an oncogene or a tumor suppressor gene?

Answer 20

it is a protein that connects to E2F (on oncogene) and suppresses its activity.

Question 21

pRB suppresses ______, which is an oncogene.

Answer 21

E2F

Question 22

E2F goes to the nucleus and acts as a TF, expressing ________, inducing which transition?

Answer 22

CycE

G1/S transition

Question 23

what oncogene acts as a TF that induces CycE expression, inducing transition from G1 to S phase? what suppresses this?

Answer 23

E2F

pRB

Question 24

an oncogenes normal activity is to ______ the cell cycle.

Answer 24

progress

Question 25

a tumor suppressor gene functions to ______ the cell cycle

Answer 25

slow

Question 26

RB, p53, p16 (CKIs) are examples of:

Answer 26

tumor supressor genes

Question 27

myc, ras, raf, cdc25, Cdks, cyclins, EGFR are examples of:

Answer 27

oncogenes

Question 28

_____/_____ detect DNA damage

Answer 28

ATM/ATRs

Question 29

ATM/ATRs can activate _____ (a CKI) which assures cells have time to repair damage or if the damage is too extensive, initiate apoptosis

Answer 29

p53

Question 30

p21 inhibits ____s

Answer 30

CDKs

Question 31

reverse in inhibition of ______ allows the cell to progress to M phase from G2 phase

Answer 31

CycB

Question 32

in response to mitogen, cyc____-Cdk phosphorylates E2F, causing it to express cyclin E and A

Answer 32

D