Control of the cell cycle

Question 1

there are two irreversible points in cell cycle

Answer 1

Replication of DNA

Separation of sister chromatids

Question 2

checkpoints

see slide 23-26

Answer 2

Allows cell cycle to respond to internal state of cell and integrity of genetic material
Allows cell cycle to respond to environmental signals

Question 3

name checkpoints

Answer 3

G1 transition
G2/M transition
metaphase to anaphase transition

Question 4

What happens once you pass the G1 transition

Answer 4

commit to cell cycle and dna replication

Question 5

what does the G1 transition check for in order for cell to proceed to delay or divide

Answer 5

Cell size
Nutrients
Growth factors (environment ok?)
DNA damage

Question 6

What happens at the G2/M transition

Answer 6

Cell size
DNA replication
DNA damage
is cell ready for mitosis

Question 7

what happens at the metaphase-anaphase transition

Answer 7

spindle assembly check
chromosome alignment and connected to spindle
to proceed with mitosis

Question 8

Cyclin-dependent kinases (Cdks)

Answer 8

central component of cell cycle control

Question 9

what does the activity of the cdks depend on

Answer 9

where in cell cycle it is

Question 10

name 2 key components of cell cycle

slide 27

Answer 10

protein kinase

cyclins

Question 11

protein kinase

Answer 11

when cdk binds with cyclin it forms protein kinase

no cyclin inactive

Question 12

cyclin

Answer 12

Proteins that undergo process of synthesis and degradation each cell cycle
Direct Cdk to specific target proteins at different times during cell cycle

Question 13

4 classes of cdks

see slide 28 graph

Answer 13

G1/S cyclin
S cyclin
M cyclin
G1 cyclin

Question 14

G1/S cyclin

Answer 14

Activate Cdk in late G1
Trigger progression through Start or Restriction point
Levels fall in S phase

Question 15

S cyclin

Answer 15

Bind Cdks after Start or Restriction point

Stimulate chromosome duplication (DNA replication)

Question 16

M cyclin

Answer 16

Stimulate entry into mitosis

Levels fall in mid-mitosis

Question 17

G1 cyclin

Answer 17

Help govern activities of G1/S cyclins

Question 18

How is cdk fully activated

Answer 18

Cdk-activating kinase (CAK)

Question 19

How does cdk activate at t loop

see slide 29

Answer 19

T loop partially blocks Cdk active site (B) = partially active
Phosphorylation at T loop frees Cdk active site (C) = fully active

Question 20

when is cdk not active

Answer 20

no cyclin attached

Question 21

Cyclin-Cdk complex inhibited by:

Answer 21

Phosphorylation by Wee1 kinase

Binding of Cdk inhibitor proteins (CKIs)

Question 22

Phosphorylation of Wee1 kinase does

Answer 22

controls m-cdk activity

Question 23

Binding of Cdk inhibitor proteins (CKIs)

Answer 23

Governs G1/S- and S-Cdks

Question 24

what is an Anaphase-promoting complex

Answer 24

cyclosome (APC/C)

Question 25

cyclosome

Answer 25

Member of ubiquitin ligase family of enzymes

Catalyzes ubiquitylation and destruction of two major types of proteins

Question 26

when is cyclosome active

Answer 26

Remains active during G1

Turned off when G1/S-Cdk is activated

Question 27

2 types of cyclosome

Answer 27

securin

G1/S cdk

Question 28

what does securin do

Answer 28

Protects protein linkages holding sister chromatids in early mitosis
When destroyed, activates protease that separates sister chromatids (anaphase)

Question 29

what do G1/S cdk do

Answer 29

Destruction inactivates most Cdks

Dephosphorylation of Cdk targets required for completion of mitosis

Question 30

look at slide 31

confusing may need to ask question to him

Answer 30

slide 31