Cell Cycle Regulation

Question 1

Abnormal Cell Cycle Results:

1. Inappropriate proliferation = [1]
2. Enter S Phase with DNA dmaage = [2]
3. Errant chromosome separation = [3]
4. Errant cell growth = [4]

Answer 1

[1] cancer
[2] mutations in genome
[3] aneuploidy, cell death
[4] inappropriate organelle distribution

Question 2

The CDK Complex: The Cell Cycle Machinery is [1] dependent. It is a kinase in nature, but it is inactivated unless it it paired with [1].

Answer 2

[1] Cyclin

Question 3

[1] CDKIs inhibit kinase and catalytic activity regardless of the cell cycle checkpoint. Inhibition occurs WITH the cyclin as part of the complex.

Answer 3

[1] CIP/KIP

– note: these numbers are ABOVE the “teens” in number

Question 4

[1] CDKIs only bind to G1 checkpoint CDKs (CDK4 or CDK6), displacing [2]

Answer 4

[1] INK4
– note: these numbers are IN the “teens”
– p16, p15, p18, p19
[2] Cyclin D

Question 5

The CDK [1] is found at the Mid G1 checkpoint.

The Cyclin [2] is used.

Answer 5

[1] CDK4 or CDK6

[2] Cyclin D

Question 6

The CDK [1] is found at the G1/S checkpoint.

The Cyclin [2] is used.

Answer 6

[1] CDK2

[2] Cyclin E

Question 7

The CDK [1] is found at the S checkpoint.

The Cyclin [2] is used.

Answer 7

[1] CDK2

[2] Cyclin A

Question 8

The CDK [1] is found at the G2/M checkpoint.

The Cyclin [2] is used.

Answer 8

[1] CDK1

[2] Cyclin A

Question 9

We have a CDK4/6 and Cyclin D. We must be at the [1] checkpoint. This is a [2]-dependent stage.
[3] is the substrate for this checkpoint. It is normally active in the hypophosphorylated state. In this state, it sequesters [4].

Answer 9

[1] Mid G1
[2] growth factor
[3] Rb
[4] E2F

Question 10

[1] is freed and initiates transcription at the G1 checkpoint. It starts producing [2] and more of itself to prepare for late G1 and S phase entry.

Answer 10

[1] E2F

[2] Cyclin E

Question 11

S-Phase SCF Ubiquiting Proteolysis:
The G1 cyclin/CDK complex will phosphorylate, ubiquitinate, and destroy [2] attached to the S-phase cyclin/CDK complex. This allows this complex to start S phase and begin the DNA replication process.

Answer 11

[1] p27

Question 12

G2-M Checkpoint - activating Mitotic Cyclins:
During mitosis, the cyclin [1] is in high concentration.
[2] will phosphorylate a tyrosine and INACTIVATE the B-CDK
[3] will phosphorylate the threonine with activating power, but the complex is still inactivated due to [2]
Finally, [4] will dephosphorylate at the tyrosine location to fully activate the B-CDK

Answer 12

[1] Cyclin B
[2] Wee1
[3] CAK
[4] Cdc25

Question 13

The two replicated chromosomes are held together at the centromere by a protein called [1] and cohesin.
In anaphase a protein called [2] that is normally inhibited by [3] will cleave [1] and allow separation of the chromosome.

Answer 13

[1] Klesin
[2] Separase
[3] Securin

Question 14

In anaphase, [1] complex targets [2] for ubiquitination-mediated degradation to free Separase.

Answer 14

[1] APC-Cdc20

[2] Securin

Question 15

In G1, Cdh1 is [1] due to action from the G1 Cyclin CDK complex.
In anaphase, there is a Cdc14 phosphatase that is expressed that will activate Cdh1 with APC.

Answer 15

[1] phosphorylated (inactive)

Question 16

[1] will polyubiquitinate mitotic cyclin (Cyclin B) in late anaphase.

Answer 16

[1] APC / Cdh1

Question 17

There is a protein that senses DNA damage called [1]. This protein complex activates a tumor suppressor called [2]. This induces a CDK inhibitor to arrest cell cycle development.

Answer 17

[1] ATM/R

[2] p53

Question 18

If DNA damage is found, a protein called [1] can be activated to inhibit the protein Cdc25 which will indirectly inhibit CDK. The phosphate group added to the tyrosine by [2] is never removed.

Answer 18

[1] Chk1/2

[2] Wee1