Cell growth + division lecture 1 Flashcards
1
Q
Stages of cell cycle
A
- G1, S, G2, M
- Microscopy = useful for describing events
- Yeast = genetic / mechanistic info
2
Q
Experiment
Order of cell cycle
A
- Fused G1 + S w/ virus induced fusion
- G1 immediately replicated DNA
- S phase has factor that triggered DNA replication
- Fused G2 + S
- G2 x replicate its DNA
- Fused G1, S or G2 to M2 → entry into mitosis so M has dominant activity
3
Q
Experiment
Control of cell cycle
A
- Temp sensitive mutant of CDC (grow at ↓ not ↑ temp)
- Find what complements cdc mutant
4
Q
Experiment
Rate limiting component of cell cycle
A
- Fission yeast cells add to end
- Mutants that divide at smaller size
- I mutant = wee1, entered S phase but M prematurely (x 2nd growth)
5
Q
Activation of CDKs
A
- Need cyclins + to be phosphorylation
- Phosph on T161 by CAK (activates)
- Phosph on T15/Y14 by wee1 (inhibits), cdc25 reverses
- CyclinB-CDK1 assembled + immediately inhibited in G2
6
Q
Cdc25/Wee1 regulation
A
- CyclinB-CDK1 ↑ during G2
- Threshold in late G2, phosph. Cdc25 (activates) + phosph. (inhibits)
- When cell exits = reversed
- Rapid change
7
Q
Cyclin degradation
A
- Mutagenesis showed 1st 90 aa of cyclinB has D-box, recognised by ubiquitin
- Ubiquitin recognised by proteasome
8
Q
APC/C
A
- In M, APC/C active via phosphorylation by Cdc20
- Immediately inhib. by MAD/Bub until chromosomes aligned
- Then cyclin-B destroyed
