Lecture 21: Cell Cycle Control

Question 1

G1/S cyclin

Answer 1

– Bind to Cdks at the end of G1 and commit the cell to DNA replication

– Levels fall in S-phase

Question 2

S cyclins

Answer 2

– Bind to Cdks during S-phase and are required form the initiation of DNA replication

– Levels remain high until mitosis

Question 3

M cyclines

Answer 3

– Promote the events of mitosis and the G2/M transition

Question 4

G1 cyclins

Answer 4

– not found in all cells

– Help promote the passage through “start” or “restriction point” – Help govern the activity of G1/S cyclins

Question 5

APC/C

Answer 5

drives chromosome seperation, but not until all are attached correctly to the spindle

also degrades M-cyclins ending mitosis