Cell cycle & apoptosis

Question 1

What are the four strategies used to regulate the cell cycle?

Answer 1

1. Phosphorylation/dephosphorylation of cell cycle regulator proteins
2. Synthesis/degradation of cyclins and CDK
3. CDK inhibitors
4. Phosphorylation/dephosphorylation of Rb

Question 2

What is the role of cyclin?

Answer 2

Cyclin allows the cell to move forward with growth/proliferation. It does this by binding to CDK, creating an active complex that phosphorylates proteins involved in the cell cycle.

Question 3

What is the role of CDK?

Answer 3

CDK is inactive by itself but when bound to cyclin signals the cell to continue with growth/proliferation.

Question 4

What are CKIs?

Answer 4

They are CDK inhibitors. They inhibit cell growth/proliferation by inhibiting CDK.

Question 5

What have CKIs been used for?

Answer 5

They have been explored for the treatment of chronic lymphocytic leukemia. If the dosage is not correct, however, CKIs can inhibit normal cell proliferation too much.

Question 6

What does p53 do?

Answer 6

p53 is one of the regulators of the cell cycle. If it detects damage in a cell, it will stop any further cell growth/division until this damage can be fixed. If the damage can’t be fixed, it initiates apoptosis.

Question 7

What does Rb do?

Answer 7

Rb is normally bound to E2F and inhibits cell growth and division. If Rb is phosphorylated by the CDK-cyclin complex, it no longer binds E2F, which then can initiate further growth/proliferation.

Question 8

What disease is associated with defective Rb?

Answer 8

Defective Rb is associated with retinoblastoma which causes tumors in the eyes and elsewhere in the body.

Question 9

What disease is associated with problems with p53?

Answer 9

LiFraumeni