Cell Cycle / Mitosis

Question 1

The enzymes and proteins necessary for cell division are synthesized in which phase?

Answer 1

G2

Question 2

A mutation in Cyclin E that interferes with its binding to Cdk2 would prevent which of the following processes?

Answer 2

Passage from G1 to S

Question 3

The DNA checkpoint kinases, Chk1 and Chk2, phosphorylate Cdc25 resulting in its inhibition. Cdc25 is required for the activation of both Cdk1 and Cdk2. Inhibition of Cdk1 would lead to

Answer 3

G2 Phase arrest

Question 4

Growth factors induce the synthesis of?

Answer 4

Cyclin D

Question 5

During meiotic prophase, which of the following is characteristic of the synaptonemal complex?

It forms between homologous chromosomes.

It holds sister chromatids together.

It is absent from the pseudoautosomal region of the X and Y sex chromosomes.

It is composed of condensins.

Answer 5

It forms between homologous chromosomes.

Question 6

Cytostatic factor (CSF) is responsible for maintaining Cdk1 activity levels during oocyte maturation arrest. One essential component, Mos synthesized in oocytes following meiosis I leads to the inhibition to

Answer 6

APC/C

Question 7

How does the activity of anaphase promoting complex (APC) lead to the separation of sister chromatids?

Answer 7

Degrades securin leading to the activation of separase.

Question 8

How many times is DNA replicated in the cell cycle?

Answer 8

Only one time

Question 9

How is DNA replication regulated in the cell cycle?

Answer 9

• Binding MCM helicase to replication origins during late G1, which prepares the ORC for initiating replication.
• Cdk2/Cyclin A activity during late G1/S prevents re-initiation of replication.

Question 10

How does the M phase end?

Answer 10

Cytokinesis

Question 11

What is the Restriction point?

Answer 11

The point in G1 where if no growth factors are present then the cell enters G0.

Question 12

What does Mitosis or Maturing promoting factor (MPF) do?

Answer 12

Transition from G2 to M is regulated by this.

Question 13

Name the associated Cdk and Cyclin given the Cell Cycle phase:

Early G1 through R

Answer 13

Cdk4,6 and Cyclin D

Question 14

Name the associated Cdk and Cyclin given the Cell Cycle phase:

G1 to S transition

Answer 14

Cdk2 and Cyclin E

Question 15

Name the associated Cdk and Cyclin given the Cell Cycle phase:

G2 to M transition?

Answer 15

Cdk1 and Cyclin B

Question 16

How are Cdk activated?

Answer 16

Activating phosphorylation of Thr 161 by Cdk Activating Kinase (CAK)

Question 17

How are Cdks inhibited?

Answer 17

Inhibitory phosphorylation of Tyr15 by Wee1 kinase

Question 18

How are Cdk un-inhibited?

Answer 18

Removal of inhibitory phosphorylation of Tyr 15 and Thr 14 by Cdc25 phosphatase.

Question 19

What does the CKI p27 do?

Answer 19

Binds to Cdk2/Cyclin A or E and inhibits progress through G1 and S.

Question 20

What respones to growth factors in the cell?

Answer 20

• Ras/Raf/MEK/ERK
  
  • These begin synthesis of D-type cyclins.
• If growth factor removed before R is passed, then cell goes into G0 and cyclin D is degraded
• If it is removed after the cell passes R the cell cycle will be completed.

Question 21

What is retinoblastoma protein (Rb)?

Answer 21

• Altered gene responsible for retinoblastoma (tumor of the eye)
  
  • Key regulator of transcription of genes required for cell cycle progression and DNA synthesis (Cyclin E).

Question 22

What is required to be activated for the passage through R and initiation of DNA synthesis?

Answer 22

Cdk2/Cyclin E

Question 23

What inhibits Cdk2/Cyclin E before R?

Answer 23

p27