17A Assignment

Question 1

DNA replication is initiated by____________.

S-Cdk
cohesin
nucleosome
geminin

Answer 1

S-Cdk

Question 2

M-Cdk complex is activated by_______.

inhibition of CAK phosphorylation.

phosphorylation by Wee1 kinase.

dephosphorylation by Cdc25 phosphatase.

inhibition of cyclin binding.

Answer 2

dephosphorylation by Cdc25 phosphatase.

Question 3

CKIs such as p27 ____________.

inhibit the cyclin-Cdk complex

activate the cyclin-Cdk complex

activate the catalytic activity of Cdk

inhibit cyclin binding to Cdk

Answer 3

inhibit the cyclin-Cdk complex

Question 4

Cdk activity is stimulated by phosphorylation of the T-loop by ________.

CAK
APC
Cyclin
Cdc25

Answer 4

CAK

Question 5

EdU incorporation marks cells in……….

Start phase
G1 phase
S phase
M phase

Answer 5

S phase

Question 6

M-cyclin _______________.

levels fall toward the end of M phase as a result of ubiquitylation and degradation.

levels rises markedly during G1 phase.

is induced by phosphorylation of cyclin.

is inhibited by M-Cdk.

Answer 6

levels fall toward the end of M phase as a result of ubiquitylation and degradation.

Question 7

Which of these techniques can be used to separate cells rapidly based on their fluorescence signal corresponding to their DNA content?

Phase contrast microscopy
Flow cytometry
Agarose gel electrophoresis
Western blotting

Answer 7

Flow cytometry

Question 8

Cdk activity fluctuates during the cell cycle, partly because ________________.

cyclin levels change during the cycle

Cdks are rapidly degraded

the Cdks inactivate the cyclins

levels of Cdks fluctuate throughout the cell cycle.

Answer 8

cyclin levels change during the cycle

Question 9

Which of these statements about Cdc25 phosphatase is true?

Cdc25 inhibits Cdk activity.

Cdc25 maintains Wee1 phosphorylaiton of Cdk.

Cdc25 increases Cdk activity.

Cdc25 prevents Cyclin binding to Cdk.

Answer 9

Cdc25 increases Cdk activity.

Question 10

One half of a duplicated chromosome at the end of S phase is called

Sister chromatid

Kinetochore

Securin

Condensin

Answer 10

Sister chromatid

Question 11

A key control system crucial for triggering cytokinesis is………….

Start transition

G2/M transition

Metaphase to anaphase transition

Answer 11

Metaphase to anaphase transition

Question 12

If cell cycles were repeated with only the S phase and M phases, what is likely to occur?

The cells produced would get smaller and smaller.

Cells would get larger and larger.

The mitotic spindle could not assemble.

Cells would not be able to replicate their DNA.

Answer 12

The cells produced would get smaller and smaller.

Question 13

Which of these fluorescently-tagged proteins can be used to monitor G2 phase in live cells?

Cdt1
APC/C
S-Cdk
Geminin

Answer 13

Geminin

Question 14

Which of these factors inactivates Cdks by adding phosphates on specific sites on Cdks?

Cdc25
Wee1
Greatwall kinase
Ensa

Answer 14

Wee1

Question 15

Activation of Greatwall kinase………..

activates PP2A-B55

inhibits PP2A-B55

inhibits M-Cdk activity

inhibits M-CDK substrate phosphorylation

Answer 15

inhibits PP2A-B55

Question 16

Mutations in Ensa that prevents its binding to PP2A-B55 will………..

activate Greatwall kinase.

inhibit PP2A-B55 activity in early mitosis.

lead to constitutive phosphorylation of M-Cdk substrates.

keep PP2A-B55 active in early mitosis.

Answer 16

keep PP2A-B55 active in early mitosis.

Question 17

Which of these mechanisms serve as positive feedback to activate M-Cdks?

Addition of phosphates on M-Cdk by Wee1

Inhibition of Cdc25 activity

Inhibition of Wee1 by M-Cdk

Activation of PP2A-B25

Answer 17

Inhibition of Wee1 by M-Cdk

Question 18

CAK-dependent phosphorylation of M-Cdk is sufficient to fully activate M-Cdk activity even in the presence of Cdk phosphorylation by Wee1?

True
False

Answer 18

False