ch. 21 Flashcards Preview

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Flashcards in ch. 21 Deck (16):
1

temporarily in G0 phase

Quiescence

2

permanently in G0 phase

Senescence

3

Some cells lose the ability to replicate after

differentiation

4

concentrations vary throughout the cell cycle due to synthesis and degradation

Cyclin

5

•Enzymes present in constant concentrations
•Activity depends on cyclin concentration

Cyclin-dependent kinases (CDK)

6

Occurs toward the end of growth phase 1 (G1)
Checks if cell is big enough and made the proper protein for synthesis phase


Cell growth check point/restriction pointIF NOT

cell goes through resting period until ready (G0)

7

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

M checkpoint

if not ready=Apoptosis

8

ensures cell is ready for mitosis

G2 checkpoint

if not ready=Apoptosis

9

Tumor suppressor protein

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

RB protein

10

hyperphosphorylate RB, so RB can no longer inhibit E2F

cell enters S phase

11

Tumor suppressor protein

stimulates synthesis of p21

p53

12

Stops cell cycle progression, so DNA damage can be fixed

p21 to fix

If cannot be fixed p53 induces apoptosis

13

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

p53

14

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

Human Papillomavirus (HPV)

15

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

dephosphorylated

16

Most cell progression is halted in what stage

G1 checkpoint at G0