Chapter 5

Question 1

What are the 4 phases of cell division?

Answer 1

G1, S, G2 and M

Question 2

What is the goal of G1?

Answer 2

Prepare for DNA synthesis (growth phase). Accumulate ingredients for DNA synthesis

Question 3

What is the goal of S-phase?

Answer 3

DNA replication

Question 4

What is the goal of G2?

Answer 4

Prepare for mitosis?

Question 5

What is the M-phase?

Answer 5

Mitosis

Question 6

What is the difference between G2 and Prometaphase of Mitosis?

Answer 6

Cyclin B1 - CDK1 complexes are inactive in G2 and all of them are active in prometaphase.

Question 7

When do the sister chromatids get separated?

Answer 7

During Anaphase

Question 8

What are the subphases of mitosis?

Answer 8

Prophase, prometaphase, metaphase, anaphase, telophase

Question 9

When is Cyclin D the most active?

Answer 9

In the beginning, but it keeps being active during the whole cell division cycle

Question 10

When is Cyclin E the most active?

Answer 10

During transition from G1 to S-phase

Question 11

When is Cyclin A the most active?

Answer 11

During the G2-phase

Question 12

When is Cyclin B the most active?

Answer 12

During transition from G2 to M-phase

Question 13

Which proteins inhibit Cyclin D?

Answer 13

The INK proteins (p16, p15, p18, p19)

Question 14

Which proteins inhibit other cyclins than Cyclin D

Answer 14

p57, p27 and p21

Question 15

What cyclin does CDK4 bind to?

Answer 15

Cyclin D

Question 16

What cyclin does CDK2 bind to?

Answer 16

Cyclin E and Cyclin A

Question 17

What cyclin does CDK1 bind to?

Answer 17

Cyclin B1

Question 18

What protein target genes does RB protein repress?

Answer 18

E2F target genes

Question 19

Which cyclin is activated through extracellular stimuli?

Answer 19

Cyclin D

Question 20

What does the Cyclin D/CDK4 comples do with RB?

Answer 20

It phosphorylates RB and inactivates it

Question 21

What does the inactivation of RB lead to?

Answer 21

Inactivation of RB ends the inhibition of E2f transcription factor, which then enables the production of Cyclin E. Cyclin E then phosphorylates RB even more and more Cyclin E is produced. The high amount of Cyclin E signals the transition from G1 to S-phase

Question 22

How does p53 inhibit cyclins?

Answer 22

p53 activates p21, which then binds to the cyclin/cdk complexes and inhibits them, leading to cell cycle arrest

Question 23

What does p16 inhibit?

Answer 23

p16 prevents the binding of cdk to cyclins by binding to cdk

Question 24

What does Flavopiridol do?

Answer 24

It inhibits cyclin/cdk function in various cell phases.

Question 25

In what phase are the chromosome checked for DNA damage?

Answer 25

In the G1 phase, after the DNA strands have been replicated

Question 26

What kind of cell cycle control is lost during carcinogenesis?

Answer 26

Mostly loss of G1 control, but sometimes G2 control

Question 27

What important control protein is lost in most tumors?

Answer 27

p53