regulation of cell cycle (13)

Question 1

when does the commitment to proceed into mitosis occur?

Answer 1

shortly before the beginning of S phase

Question 2

where are the two other checkpoints in the cell cycle?

Answer 2

entry into mitosis (between G2 and M)

transition from metaphase to anaphase (during M)

Question 3

what is the regulatory subunit that must be combined with the cdk to make it active?

Answer 3

a cyclin

Question 4

describe the concentration flow of cyclin and the kinase subunits during the cell cycle

Answer 4

The concentration of the cyclin subunit of a mitotic cdk increases gradually during the cell cycle then decreases suddenly
-the kinase concentration stays constant

Question 5

why is there a “lag” between the increase in cyclin activity and the activation of cdk? (3 factors/steps)

Answer 5

1. The cyclin subunit must be synthesized and must bind to the kinase
2. The catalytic subunit is phorphorylated. 1 phosphate is needed for CDK activity, the other inhibits the cdk activity
3. A phosphatase removes the inhibitory phosphate, activating the cdk

Question 6

what is the name of the cdk inhibitor kinsase?

Answer 6

wee1

Question 7

what is the name of the cdk activating kinase?

Answer 7

Cak

Question 8

what is the final step in cdk activation?

Answer 8

removal of the inhibitory phosphate by a protein phosphatase starts a positive feedback loop. Activity of a few molecules of the cdk as a protein kinase stimulates the phosphatase to make more active cdk molecules

Question 9

how do you inactivate cdk?

Answer 9

1. Cyclin subunit is ubiquitylated by an E3 ubiquitin ligase, targeting the cyclin subunit for the proteolytic destruction by the proteosome
2. The activating phosphate is removed from the kinase subunit

Question 10

how many kinetchores need to be attached for the E3 ligase activation?

Answer 10

all of them

will not occur if even one isn’t attached

Question 11

what is the APC?

Answer 11

a ubiquitin E3 ligase, targeting proteins for desctruction

Question 12

what activates the APC?

Answer 12

tension on all the kinetochores

Question 13

what are the two main proteins that p53 activates transcription for?

Answer 13

p27 and p21

Question 14

what is cisplatin? why and how does it work?

Answer 14

it is a DNA damaging agent
why it works in brca cancers:
-If you damage the dna enough, and you cant fix it—you can induce apoptosis

Question 15

in addition to DNA damaging agents, what is another molecule that can be used in brca cancers?

Answer 15

dna repair inhibitors

ex. PARP inhibitors

Question 16

what is the action of G1 CDK?

Answer 16

CDK inactivates the retinoblastoma protein (Rb) and triggers the synthesis of genes needed to progress into S phase