10-24: Cell control/division II

Question 1

What are the steps of the cell cycle and checkpoints?

Answer 1

1) Enter cell cycle and proceed to S phase
2) G2/M checkpoint: enter MITOSIS
3) Metaphase-to anaphase: Enter ANAPHASE and proceed to cytokinesis

Question 2

Start checkpoint in late G1

Answer 2

starts DNA replication and S phase of cell cycle

Question 3

Orgins of replication

Answer 3

Specific sites where DNA replication occurs

Question 4

Prereplication complex

Answer 4

Late mitosis-early G1
- assembles at the orgins of rep
- DNA replication origin licensing

Question 5

Preinitiation complex

Answer 5

Nucleated at the onset of S phase

Question 6

ORC

Answer 6

Pre-replication protein
- loads other initiation proteins Cdc6 and Cdt1

Question 7

Mcm

Answer 7

Helicase
- loads to ORC, Cdc6, Cdt1 to form the pre-replication protein

Question 8

Licensing control prevents ________

Answer 8

re-replication

Question 9

What does the preinitiation complex do to pre-RC complex?

Answer 9

• Cdc6 degradation and Cdt1 inhibition
• Phosphorylation of ORC (can’t recruit)

Question 10

S-cdk

Answer 10

pre-initiation complex

Question 11

What increases at G2/M checkpoint that drives entry to mitosis?

Answer 11

M-Cdk

Question 12

What does M-cdk induce?

Answer 12

-mitotic spindle
-chrom condensation
-nuc envelope breakdown
-chrom alignment
-anaphase entry

Question 13

Prophase

Answer 13

-chrom condense
-centrosomes move to opposite sides of cell
-nucleoli disappear

Question 14

Prometaphase

Answer 14

-MT attatch to kinetochores
-metaphase plate

Question 15

Anaphase

Answer 15

-sister chromatids pulled apart
-chromatids are moved towards opposite poles by shortening of the spindle MTs

Question 16

Telophase

Answer 16

chromosomes decondensed
spindle apparatus disassembles (nucloili reapear)

Question 17

Cdc25 phosphatase

Answer 17

removes the inhibitory phosphates from M-cdk = activation

Question 18

Active m-cdk

Answer 18

• Promotes Cdc25 activity
• Inhibits Wee1

Question 19

What is securin’s role in Metaphase to anaphase transition?

Answer 19

• securin bound to separase
• cdc20 binds to the active APC/C
• active apc/c degrades securin
• separase cleaves cohesion
• sister chromatids separated

Question 20

Mitogen

Answer 20

Stim G1/S-cdk

Question 21

Growth factors

Answer 21

stim protein syth and inhibit protein degration

Question 22

Survival factors

Answer 22

suppress apoptosis

Question 23

GTPase Ras

Answer 23

• activated by mitogen
• signaling protein that activates MAP kinase and causes gene expression

Question 24

Ras/MAPK

Answer 24

Gives a signal from the extracellular environment to the nucleus for the cell to grow, divide, or differentiate

Question 25

Myc

Answer 25

• early gene expression (ras/mapk) causes activation

Question 26

G1-Cdk

Answer 26

Activates E2F, which regulates DNA synthesis

Question 27

Activation of E2F

Answer 27

Mitogen induced cell cycle entry and S phase initiation

Question 28

Growth factors

Answer 28

affect concentrations of cyclins and CDKs

Question 29

Rapamycin (TOR)

Answer 29

nutrient-sensing signaling network that controls cell growth