Chapter 11.2.2 (Exam 2) CDKs

Question 1

Why is regulating CDKs the key to regulating cell division?

Answer 1

Progress through the cell cycle depends on CDKs

Question 2

How are CDKs regulated?

Answer 2

CDKs can be regulated by the presence or absence of cyclins

Cyclins are present cyclically: they are made only at certain times in the cell cycle

Question 3

Cyclin–CDKs act at cell cycle checkpoints to regulate progress. When are these checkpoints located in the cell cycle?

Answer 3

3 checkpoints in interphase and 1 in mitosis

Question 4

What is one example of the checkpoints in the cell cycle?

Answer 4

At checkpoint R, if DNA is damaged, p21 protein is made

p21 binds to G1-S CDKs active sites, preventing their activation (competitive inhibition)

The cell cycle pauses while DNA is repaired

Question 5

The cell cycle is also influenced by external signals. What is an external influence on the cell cycle?

Answer 5

Growth factors: Some cells divide infrequently or go into G0 and must be stimulated by growth factors to divide

Question 6

What are two examples of external growth factors?

Answer 6

Platelet-derived growth factor

Interleukins and erythropoietin