9.9 Cell Cycle Flashcards
what does the cell do in G1 phase?
it gathers nutrients and energy. Lives and prepares
what does the cell do in the S phase?
it commits to duplication and division. DNA/organelle replication
what does the cell do in the G2 phase?
it checks and fixes DNA
DNA repair
what does the cell do in M phase?
divide
what are the three locations of the major cell cycle checkpoints?
G1/S transition
G2/M transition
metaphase/anaphase transition
what causes transition between G1 to S phase?
increase in CycE-Cdk2 levels
CycE-Cdk2 increase levels of what other cyclin?
CycA
CycA degrades _____ (what cyclin)
CycE
what does CycA do?
it induces DNA replication in S phase
CycB (inactivated) increases and is maximal before ____ phase. It degrades Cyc___.
M phase
CycA
CyB is regulated by phosphorylation by two enzymes: ______ and ______. Which inhibits and which activates?
CAK - activated
Wee - inhibits
to activate CycB, the inhibitory phosphate needs to be removed by _______.
Cdc25
what activated Cdc25 to dephosporylate the inhibitory phosphate on CycB?
complete and accurate DNA replication
once the inactivating inhibitory phosphate is removed from CycB, what phase transition can happen?
G2 –> M phase
what is the “anaphase wait” signal?
all kinetochores are attached with a microtubule and ready to split
Wee1 inhibits what?
CycB-Cdk1
once anaphase is reached, what is expressed? What do they do?
APCs are expressed, they degrade CycB and CycA
what regulates CDKs? (4)
- cyclin changes (either increase in expression through TFs or degradation such as APCs)
- Phosphorylation (Wee, CAK)
- CKIs (CDK inhibitors) in G1
what are CKIs? (p21, p27, etc)
inhibitors of CDK
what is pRB? Is it an oncogene or a tumor suppressor gene?
it is a protein that connects to E2F (on oncogene) and suppresses its activity.
pRB suppresses ______, which is an oncogene.
E2F
E2F goes to the nucleus and acts as a TF, expressing ________, inducing which transition?
CycE
G1/S transition
what oncogene acts as a TF that induces CycE expression, inducing transition from G1 to S phase? what suppresses this?
E2F
pRB
an oncogenes normal activity is to ______ the cell cycle.
progress
a tumor suppressor gene functions to ______ the cell cycle
slow
RB, p53, p16 (CKIs) are examples of:
tumor supressor genes
myc, ras, raf, cdc25, Cdks, cyclins, EGFR are examples of:
oncogenes
_____/_____ detect DNA damage
ATM/ATRs
ATM/ATRs can activate _____ (a CKI) which assures cells have time to repair damage or if the damage is too extensive, initiate apoptosis
p53
p21 inhibits ____s
CDKs
reverse in inhibition of ______ allows the cell to progress to M phase from G2 phase
CycB
in response to mitogen, cyc____-Cdk phosphorylates E2F, causing it to express cyclin E and A
D
