Cancer

Question 1

Carcinogenesis

Answer 1

uncontrolled cell growth and cell spreading

Question 2

Hyperplasia

Answer 2

cells resemble those in normal tissue

Question 3

Dysplasia

Answer 3

cells are cytologically abnormal

Question 4

Cancer

Answer 4

malignant tumours

Question 5

Cdks

Answer 5

cyclin dependent kinases

~ protein kinases that phosphorylate specific serine/threonine residues

Question 6

Cyclin D

Answer 6

G1 cyclin

activates Cdk4 or CDK6

Question 7

Cyclin E

Answer 7

G1/S cyclin

activates Cdk2

Question 8

Cyclin A

Answer 8

S cyclin

activates Cdk2

Question 9

Cyclin B

Answer 9

M cycline

activate Cdk1

Question 10

Each cyclin-cdk complex activates…

Answer 10

~ events in their cell cycle phase

~ cyclin-cdk in the next cell phase e.g. by promoting expression

Question 11

Name the mechanisms used to regulate Cdk activity

Answer 11

1. activation by association with cyclins
2. postive regulation by phosphorylation
3. negative regulation by phosphorylation
4. cyclin kinase inhibitors

Question 12

1. activation by association with cyclins

Answer 12

when bound to cyclin, the Cdk active site becomes unburied (active) and available to bind to

Question 13

2. postive regulation by phosphorylation

Answer 13

activation - phosphorylation of a threonine residue by cdk-activating kinases (CAK)
~ occurs after cyclin binding

Question 14

3. negative regulation by phosphorylation

Answer 14

phosphorylation inactivates cdk by blocking ATP binding site
controlled by:
Wee1 kinase (G1, S, G2)
Cdc25 phosphatase (G2)
~ creates a positive feedback loop

Question 15

4. cyclin kinase inhibitors

Answer 15

Two types:
~ bind to cyclin-cdk complex - distorts structure and prevents ATP binding
~ bind to cdk only - alter the structure and prevent binding with cyclin