BSI Lecture 21-22 Cell Cycle Control

Question 1

T or F? MAPK activates G1-CDK and G1/S-CDK by phosphorylating them.

Answer 1

False

Question 2

T or F? G1-CDK and G1/S CDK activate S-CDK by phosphorylating it.

Answer 2

They phosphorylate Rb

Question 3

P21 inhibits?

Answer 3

G1/S-CDK and S-CDK

Question 4

CdKs must be bound to _______ to be active.

Answer 4

cyclin

Question 5

What are CdKs?

Answer 5

Cyclin dependent kinases

Question 6

Cyclin bound to a CdK forms a _________ ______.

Answer 6

Cyclin-CDK complex

Question 7

How are cyclin degraded?

Answer 7

By the ubiquitan-proteasome system

Question 8

There are a variety of cyclin-CdK complexes, what are they?

Answer 8

G1-CDK, G1/S-CDK, S-CDK, and M-CDK

Question 9

Aside from cyclin binding, CdKs can also be regulated by _____ ___ and ______ ________ proteins (e.g p21, p27)

Answer 9

Phosphorylation status; CDK inhibiting proteins

Question 10

T or F? Cyclin-Cdks are active in early G1.

Answer 10

False, not active

Question 11

In mammals, what external cellular signal is required to initiate the cell cycle?

Answer 11

Mitogen

Question 12

Epidermal GF, fibroblast GF, vascular endothelial GF, platelet derived GF, neurotrophic GF, insulin-like GF, hepatic GF, are examples of __________ ________ / ________

Answer 12

Growth factors/mitogen

Question 13

Mitogen stimulates activity of _____ and ____ which leads to activation of S-CdK and transition into S-phase.

Answer 13

G1-CDK and G1/S-CDK

Question 14

_____ activity is responsible for transition through the M-phase.

Answer 14

M-CDK

Question 15

T or F? At the end of M-phase/beginning of Gl phase, all active CdKs are inactivated

Answer 15

True

Question 16

G1-CDK and G1/S-CDK phosphorylates _______.

Answer 16

Rb

Question 17

Phosphorylation of Rb leads to the release of _____.

Answer 17

E2F

Question 18

______ is a transcription factor that regulates the transcription of genes necessary for S-phase

Answer 18

E2F

Question 19

DNA polymerase and S-CDK Cyclin are regulated by ______

Answer 19

E2F

Question 20

Mitogen binding leads to stimulation of the ____/_____ pathway

Answer 20

Ras/MAPK

Question 21

MAPK activates a gene regulatory protein (transcription factor) , what is the example Dr Naylor gave in class?

Answer 21

ELK2

Question 22

The ELK2, a transcription factor, increases the transcription of ____

Answer 22

Myc

Question 23

_____ is a transcription factor which then regulates the transcription of several more genes, including cyclin D, SCF subunit, and E2F

Answer 23

Myc

Question 24

Cyclin D expression leads to the activation of _______

Answer 24

G1-CDK

Question 25

SCF subunit expression leads to the degradation of p27, which leads to activation of G1/S-CDK: SCF is what kind of protein?

Answer 25

Ubiquitan-ligase

Question 26

T or F? Increased E2F expression and increased release of E2F from Rb leads to enhanced expression of genes required for S-phase.

Answer 26

True

Question 27

DNA damage leads to activation of either ____ or _____ kinsase which then phosphorylates p53.

Answer 27

ATM or ATR

Question 28

p53 is a ______ _____

Answer 28

Transcription factor

Question 29

When there is no DNA damage, p53 normally is degraded by being tagged w/Ubiquitin by _______

Answer 29

MDM2

Question 30

When p53 is phosphorylated, ______ cannot bind to it and cannot ubiquitinate it

Answer 30

MDM2

Question 31

p53 increases the transcription of ______

Answer 31

p21

Question 32

____ binds to G1/S-CdK and S-CdK inhibiting their activity

Answer 32

p21

Question 33

T or F; Activation of G-CdK which regulates M-phase

Answer 33

False, M-CDK

Question 34

How is M-CDK complex formed?

Answer 34

M-Cyclin binds to CDK-1

Question 35

T or F? Both CAK and Wee1 phosphorylate M-CDK.

Answer 35

True

Question 36

CAK adds an ______ phosphate and Wee1 adds an _______ phosphate.

Answer 36

Activating; inhibitory

Question 37

Cdc25, once phosphorylated by _______ removes the inhibitory phosphate that Wee1 added

Answer 37

S-CDK

Question 38

T or F? Once activated, in a positive feedback manner, M-CDK can enhance activation of more S-CDKs

Answer 38

False, activation of more M-CDKs

Question 39

____ can phosphorylate cdc25 to enhance its activity and Wee1 to inhibit its activity

Answer 39

M-CDK

Question 40

_____ regulates most events in M phase, such as APC activation and chromosomal segregation

Answer 40

M-CDK

Question 41

What does active APC do to activate separase?

Answer 41

Ubiquitinates securin

Question 42

How does APC trigger anaphase?

Answer 42

By ubiquitylizes securin, which cause activation of separase which then cleaves and dissociate cohesins