Cell Cycle

Question 1

what are the phases of the cell cycle

Answer 1

G1 (gap 1) -> S (synthesis) -> G2 (gap 2) - M (mitotic)

Question 2

cyclin dependent kinase

Answer 2

• phosphorylates certain serines or threonines on target proteins
• specific CDK’s exist for specific phases of the cell cycle

Question 3

cyclin protein (3)

Answer 3

• activate CDK by forming a complex with it
• G1, S, and G2 specific cyclins
• specific cyclins are made and degraded at certain times during cell cycle: G1 specific cyclin only during G1-S phase

Question 4

CDK-cyclin function

Answer 4

• complex phosphorylates proteins required for particular phases
• CDK-cyclin in G1 would phosphorylate proteins required to initiate S phase
• may activate or inactivate target protein after phosphorylation

Question 5

caspases function

Answer 5

• catalyse cascade of proteolytic events that results in fragmentation of DNA, destruction of cytoskeleton, and breakdown in organelles

Question 6

how is cell number modulated

Answer 6

• both cell division and death can be promoted or inhibited by internal and external signals
• two major checkpoints during cell cycle where the cell can be arrested in necessary

Question 7

where are the two major checkpoints for regulation in the cell cycle

Answer 7

• before cell enters S phase

- before cell enters M phase`

Question 8

what does the cell check at checkpoints (3)

Answer 8

• did the cell grow enough
• is the DNA okay; if not, then repair DNA
• is there already enough cells in the tissue