Cell Division Regulation

Question 1

During the M phase regulatory step of the cell cycle, which two proteins engage in a “tug of war”?

Answer 1

• Cdk Activating Kinase (CAK) (+)
• Wee-1 (-)

Question 2

During the M-phase “Tug of war”, what is the last key player that helps determine who wins?

Answer 2

Cdc25 Phosphatase

• Removes Wee-1’s phosphate and allows M-CDK to get to work!

Question 3

Which key tumor suppressor regulates the G1 checkpoint?

Answer 3

p53

(Makes SKI and 21 to inhibt g1/s and S cdks)

Question 4

During the S Cdk phase, which two proteins bind to the ORC to form the pre-rep Complex?

Answer 4

1. Cdc6 (eventually gets killed)
2. Mcm (Helicase)

“Man-crush monday unzips”

Question 5

What does damaged DNA do to Cdc25 (Key player for M-phase regulation)

Answer 5

Blocks Cdc25 and allows wee-1 to inhibit during G2 checkpoint

Question 6

After M-cdk has done its thang, how do we exit from mitosis?

Answer 6

• Ubiquination
• Cyclin Kinase Inhibitors

Question 7

What are the two key players regulating G1 Cdk step of cellular regulation?

Answer 7

1. Rb sequester E2F
2. E2F gets freed by a phosphorylating Rb from a mitogenic signal

Question 8

What are the four kinds of Cdks and their functions?

Answer 8

1. G1 Cdk (passage)
2. G1/S Cdk (Commit replication)
3. S Cdk (replicate)
4. M Cdk (Promote Mitosis)