ch. 21

Question 1

temporarily in G0 phase

Answer 1

Quiescence

Question 2

permanently in G0 phase

Answer 2

Senescence

Question 3

Some cells lose the ability to replicate after

Answer 3

differentiation

Question 4

concentrations vary throughout the cell cycle due to synthesis and degradation

Answer 4

Cyclin

Question 5

• Enzymes present in constant concentrations

* Activity depends on cyclin concentration

Answer 5

Cyclin-dependent kinases (CDK)

Question 6

Occurs toward the end of growth phase 1 (G1)

Checks if cell is big enough and made the proper protein for synthesis phase

Answer 6

Cell growth check point/restriction pointIF NOT

cell goes through resting period until ready (G0)

Question 7

occurs in metaphase, checks tension at mitotic spindle before separating in anaphase.

Answer 7

M checkpoint

if not ready=Apoptosis

Question 8

ensures cell is ready for mitosis

Answer 8

G2 checkpoint

if not ready=Apoptosis

Question 9

Tumor suppressor protein

Keeps cell in G1 phase (resting) by binding transcription factors

Answer 9

RB protein

Question 10

hyperphosphorylate RB, so RB can no longer inhibit E2F

Answer 10

cell enters S phase

Question 11

Tumor suppressor protein

stimulates synthesis of p21

Answer 11

p53

Question 12

Stops cell cycle progression, so DNA damage can be fixed

Answer 12

p21 to fix

If cannot be fixed p53 induces apoptosis

Question 13

mutated in 90% of skin cancers & 50% of all cancer

Answer 13

p53

Question 14

Certain proteins made by this virus can bind RB & p53, rendering them in active
•Unregulated cell cycle progression & malignancy results

Answer 14

Human Papillomavirus (HPV)

Question 15

CDK1 Must be ……………………….. to bind to cyclin B & stimulate cell cycle progression

Answer 15

dephosphorylated

Question 16

Most cell progression is halted in what stage

Answer 16

G1 checkpoint at G0