Cell Bio Ch 17

Question 1

Eukaryotic cell cycle is divided in to ____ phases

Answer 1

4

Question 2

function of the cell cycle is to:

Answer 2

duplicate DNA in chromosomes accurately and separate the copies precisely in daughter cells

Question 3

Duplication of DNA occurs in _______ and requires _____ of cell cycle time.

Answer 3

S phase (synthesis phase),
half of cycle time (10-12 hours)

Question 4

cell division occurs in ______

Answer 4

M phase (mitosis)

Question 5

Two major events in M phase

Answer 5

mitosis (nuclear division) and cytokinesis (cell division)

Question 6

Many of human proteins function well in ______ due to being highly conserved.

Answer 6

yeast cells

Question 7

Model organisms to study cell cycle

Answer 7

1. budding yeast
2. frog
3. mammalian cells

Question 8

Temperature-sensitve cell-division-cycle genes helped ______

Answer 8

elucidate key aspects of cell cycle regulation.

At certain temperatures, the mutant gene causes cells to get stuck in a phase and are unable to complete cell division cycle

Question 9

normal mammalian cells stop dividing after ____ divisions

Answer 9

25-40

Question 10

_______ cell lines proliferate indefinitely.

Answer 10

immortalized cells

Question 11

Cell cycle clock checkpoints

Answer 11

start checkpoint
G2/M checkpoint
S checkpoint
metaphase-to-anaphase transition

Question 12

start checkpoint

Answer 12

Is environment favorable?

enter cell cycle, proceed to S phase

Question 13

S checkpoint

Answer 13

continue DNA replication

Question 14

G2/M checkpoint

Answer 14

All DNA replicated?
Environment favorable?
Enter Mitosis

Question 15

Metaphase-to-anaphase transition checkpoint

Answer 15

Are all chromosomes attached to the spindle?

trigger anaphase and proceed to cytokinesis

Question 16

What makes up the cell cycle clock?

Answer 16

cyclin dependent kinase (CDK) and Cyclin

Question 17

CDKs are ______ on cyclins for their kinase activity.

Answer 17

dependent

Question 18

CDK levels are _____ in a cell

Answer 18

constant

Question 19

CDK and cyclin form the ______

Answer 19

CDK-cyclin complex

Question 20

cyclin protein level ____ during cell cycle

Answer 20

change

cycle clock depends on these changes

Question 21

3 classes of cyclins defined by

Answer 21

cell cycle stage at which they bind cdks and function

Question 22

3 classes of cyclins are

Answer 22

G1/S-cyclin
S-cyclin
M-cyclin

Question 23

Inactive Cdk is blocked by ____

Answer 23

a T loop

Question 24

Binding of cyclin to Cdk causes _____

Answer 24

T loop to move out of the active site

Question 25

____ causes conformation change that activates the CDK enzyme

Answer 25

Phosphorylation of T loop

Question 26

3 types of inhibition work on CDK complex

Answer 26

Inhibitory phosphorylation, p27 (cdk inhibitory protein (CKI)), cyclin degredation

Question 27

______ can suppress CDK complex activity.

Answer 27

Inhibitory phosphorylation

Question 28

_______ phosphorylates Cdk complex to inhibit activity

Answer 28

Wee1 kinase

Question 29

_______ removes phosphate of inhibited CDK complex and reactivates it.

Answer 29

Cdc25 phosphatase

Question 30

________ can inhibit Cdk complex without phosphorylation

Answer 30

p27 or cdk inhibitory protein (CKI)

Question 31

Cdk needs ________ to be active, ______ make it inactive

Answer 31

1 phosphate | 2 phosphates

Question 32

______ adds first phosphate to activate CDK complex

Answer 32

Cdk-activating kinase (CAK)

Question 33

S-Cdk initiates ________ and helps _________

Answer 33

DNA replication | block re-replication

Question 34

______ help hold the sister chromatids of each replicated chromosome together.

Answer 34

Cohesins

Question 35

In absence of DNA damage ______ is degraded

Answer 35

p53

Question 36

activated p53 allows transcription of the _______ gene

Answer 36

p21 this protein inhibits the CDK complex, stopping cell division

Question 37

M phase is divided into six stages

Answer 37

Prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis

Question 38

________ duplicate to help form the two poles of the ________ spindle.

Answer 38

centrosomes | mitotic

Question 39

________ attach sister chromatids to the spindle

Answer 39

kinetochores

Question 40

The mitotic spindle is _______

Answer 40

bipolar

Question 41

3 types of microtubules in mitotic spindles

Answer 41

1. interpolar microtubules 2. Kinetochore microtubules 3. astral microtubules

Question 42

interpolar microtubules

Answer 42

plus ends of some microtubules interact with the plus ends of another, forming an antiparallel array

Question 43

kinetochore microtubules

Answer 43

microtubules bound to the kinetochores on the sister chromatids

Question 44

astral microtubules

Answer 44

radiate outward from the poles and help position the spindle in the cell

Question 45

___ drives entry into mitosis

Answer 45

M-CDK

Question 46

For M-Cdk to be active, it must be:

Answer 46

phosphorylated at one site and dephosphorylated at other sites.

Question 47

High level of M-cdks drive entry into mitosis by triggering _____

Answer 47

chromosome condensation (Condensin)

Question 48

complex that condenses chromosomes

Answer 48

condensin

Question 49

______ helps to assemble the mitotic spindle and makes sure each sister chromatid is attached to the opposite pole.

Answer 49

Anaphase Promoting Comlex (APC)

Question 50

_____ triggers sister-chromatid separation and the completion of mitosis

Answer 50

proteolysis

Question 51

______ inhibits _______ that breaks down cohesins to separate sister chromatids.

Answer 51

securin inhibits seperase

Question 52

anaphase promoting complex (APC) breaks down securin to un-inhibit ______

Answer 52

separase

Question 53

incomplete segregation of chromosomes will be _____ for cells

Answer 53

lethal

Question 54

unattached chromosomes send a ______ signal to the cell-cycle system

Answer 54

"stop"

Question 55

cytokinesis

Answer 55

division of cytoplasm

Question 56

formation of ____ on cell surface deepens and spreads around the cell to divide it

Answer 56

cleavage furrow

Question 57

______ is under the cleavage furrow, composed of actin and myosin filaments. Contracts and separates the cells.

Answer 57

Contractile ring