10/30: Cell-Cycle Control and Cell Division II

Question 1

Where are the checkpoint controls?

Answer 1

1. Late G1 (start checkpoint)
2. G2-M checkpoint
3. Metaphase to anaphase

Question 2

What 3 things does the cell-cycle checkpoint control system depend on?

Answer 2

1. Cdks
2. Cyclical proteolytic events
3. Transcriptinal regulation

Question 3

What are checkpoint controls designed to do?

Answer 3

Block progression through checkpoints if problems are sensed

Question 4

Passage through start checkpoint in late G1 launches?

Answer 4

DNA replication and S phase of cell cycle

Question 5

Where does DNA replication occur?

Answer 5

Specific sites or origins of replicaiton

Question 6

What is the initiation phase of DNA replication divided into?

Answer 6

1. Late mitosis-early G1

Prereplication complex assembles at the origins or replication

2. Onset S phase

Prereplication complex nucleates the formation of the preinitiation complex

Question 7

Cdks required the binding of what?

Answer 7

Cyclins

Question 8

In the absence of cyclin, CDK is in what state?

Answer 8

Inactive

Question 9

The concentration of the 3 major cyclins are

Answer 9

Induced

Question 10

The concentrations of Cdk have what kind of expression?

Answer 10

Constitutie expression

Question 11

What initiates the metaphase to anaphase transition?

Answer 11

APC/C

Question 12

What catalyzes the ubiquitation and degradaon of securin and the S- and M- cyclins?

Answer 12

APC/C

Question 13

When is APC/C turned off?

Answer 13

G1/S-Cdks are activated

Question 14

What checkpoint ensures that all the DNA has been properly replicated?

Answer 14

G2-M checkpoint

Question 15

What drives entry into mitosis and the events of early mitosis?

Answer 15

Abrupt increase in M-cdk activity at G2-M checkpoint

Question 16

What does M-Cdk induce?

Answer 16

Assemble of the mitotic spindle, chromsome condensation, promotes breakdown of the nuclear envelope, rearrangements of the actin cytoskeleton and the golgi

Question 17

What are the 5 phases of mitosis?

Answer 17

1. prophase
2. prometaphase
3. metaphase
4. anaphase
5. telophase

Question 18

What occurs during prophase?

Answer 18

sister chromatids condense and centromeres create poles

Question 19

What occurs during prometaphase?

Answer 19

there is a breakdown of the nuclear envelope and chromosomes can attach to the spindle

Question 20

What occurs during metaphase?

Answer 20

the chromosomes are aligned at the equator of the spindle

Question 21

What occurs during anaphase?

Answer 21

sister chromatids separate to form 2 daughter cells

Question 22

What occurs during telophase?

Answer 22

the sister chromatids arrived at the poles and the spindle decondenses

Question 23

What occurs during cytokinesis?

Answer 23

the cytoplasm is divided in 2 by a conrtctile ring of actin and myosin filaments and creates 2 daughter cells

Question 24

This syndrome is characterized by prenatal growth retardation

Answer 24

Roberts syndrome

Question 25

Roberts syndrome is what kind of mutation?

Answer 25

Homozygous mutation of ESCO2

Question 26

Mitogens stimulate cell division by stimulated what activity?

Answer 26

G1/S-Cdk

Question 27

What can stimulate cell growth by stimulating protein synthesis and inhibiting protein degradation

Answer 27

Growth factor

Question 28

What extracellular signals control cell division?

Answer 28

1. Mitogens 2. Growth factors 3. Survival factors

Question 29

Map Kinase leads to what?

Answer 29

1. Growth 2. Differentiation 3. Apoptosis

Question 30

What stimulates cell division mainly by stimulating G1/S-Cdk activity that inhibit intracellular negative controls that block progression through the cell-cycle?

Answer 30

Mitogens

Question 31

What suppress programmed cell death (apoptosis)?

Answer 31

Survival factors

Question 32

What stimulate cell growth (increase in cell mass) by stimulating protein synthesis and inhibiting protein degradation?

Answer 32

Growth factors

Question 33

What is a major pathway of Mitogens?

Answer 33

Small GTPase Ras

Question 34

What leads to the activation of a MAP kinase cascade?

Answer 34

Ras

Question 35

MAP kinase cascade leads to activation of what?

Answer 35

Immediate early gene expression

Question 36

What is an example of an immediate early gene?

Answer 36

Myc

Question 37

What does Myc do?

Answer 37

Increases G1-Cdk by increasing expression of genes that encode G1 cyclins

Question 38

What is a key function of G1-Cdk?

Answer 38

Activate E2F proteins

Question 39

E2F proteins are typically inhibited by an interaction between

Answer 39

E2F and Rb family

Question 40

What are the 3 growth factors in EGF?

Answer 40

1. ErK 2. JAK/STAT pathway 3. P13 kinase/AKT pathway

Question 41

What is associated with TGFb?

Answer 41

SMAD

Question 42

The activity of cyclin-CDK is further regulated by what molecule? This further phosphorylates Cdk and renders it inactive

Answer 42

Wee1

Question 43

After Wee1 renders Cdk inactive, what dephosphorylate and restores activity to the Cdk?

Answer 43

Cdc25 phosphatase

Question 44

Securin is involved in protecting the protein linkages that hold what together?

Answer 44

sister chromatids

Question 45

Degradation of securin unleashes what?

Answer 45

Anaphase

Question 46

Degradation of the S- and M- cyclins lead to the inactivation of what? This ends up completing what?

Answer 46

Cdk M phase

Question 47

When is APC/C turned off?

Answer 47

G1/S-Cdks are activated