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BIOL 1020 > Regulation of the cell cycle- lecture #15 > Flashcards

Regulation of the cell cycle- lecture #15 Flashcards

1
Q

molecular control systems exist, what are the 2 things that are critical to normal cell development?

A

timing and the rate of cell division

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2
Q

frequency of cell division varies depending on what?

A

the cell type

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3
Q

what two cells dont divide at all?

A

muscle and nerve cells

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4
Q

what do molecular regulatory mechanisms do?

A

cause differences in division

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5
Q

why do we need regulation in cells?

A

to ensure we’re making just whats required

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6
Q

what are signaling molecules?

A

protein

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7
Q

where are signaling molecules located?

A

in the cytoplasm

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8
Q

what are signaling molecules important for?

A

cell cycle control systems

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9
Q

what do signaling molecules do?

A

communicate to give an order to happen, tells the cell what to do

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10
Q

cell division is regulated at certain checkpoints that are located where?

A

internal and external

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11
Q

what kind of signals do checkpoints give? what do checkpoints do?

A

stop and go signals
regulate the cell cycle

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12
Q

at what points do checkpoints occur?

A

G1, S and G2 phases

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13
Q

what checkpoint/ phase is the most important?

A

G1

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14
Q

if the cell passes checkpoint G1, what happens?

A

the cell will move on and be committed to divide
like when you go on an airplane, once you reach a certain speed you cant stop

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15
Q

what happens if the cell does not pass checkpoint G1?

A

it will enter into G0 (G not) and not go on to divide

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16
Q

do cells stay in G0 for life?

A

some cells do
other cells are pulled out of G0

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17
Q

when a cell is pulled out of G0 what factor influences it?

A

based on external cues and enter into normal division

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18
Q

what are the two types of kinases?

A

cyclin dependent and cyclin independent

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19
Q

what does protein kinases do?

A

activate and deactivate protein via phosphorylation

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20
Q

what phases is protein kinases important for?

A

G1 and G2 phases

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21
Q

is CDK always present?

A

yes, when active or inactive

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22
Q

in order for CDK to gain activity what does it have to attach to?

A

cyclin

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23
Q

activity will increase or decrease based on what?

A

the presence of the cyclin partner

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24
Q

what does MPF do?

A

triggers the movement of the cell past G2 in mitosis

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25
Q

what is the charger to MPF?

A

when cyclin and Kinase are together

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26
Q

when does MPF decrease?

A

when cyclin decreases

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27
Q

when does cyclin increase? what happens due to this increase?

A

cyclin increases in G2 and binds to MPF

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28
Q

after cyclin binds to MPF, what does MPF do?

A

phosphorylates and activates proteins and other kinases
(MPF also deactivates)

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29
Q

when MPF activates proteins and kinases what does this initiate?

A

mitosis

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30
Q

what happens when MPF initiates mitosis?

A

proteins that cause the fragmentation of the nucleus arrive and are activated
assists with chromosome condensation
assists with spindle formation

31
Q

during anaphase what does MPF do?

A

switches itself off

32
Q

when MPF switches itself off what does this activate?

A

a process that causes destruction of its own cyclin

33
Q

what else occurs to MPF when it switches itself off?

A

inactivates MPF

34
Q

when the MPF inactivates what happens to the CDK?

A

still kept at high concentration

35
Q

what happens if we dont shut this process down?

A

cancer

36
Q

if division needs to keep happening what will continue to enter the cycle?

A

cyclin

37
Q

in order to completely deactivate this reaction what needs to happen?

A

have to break apart cyclin to deactivate reaction

38
Q

what signals are used as stop/go signs at the checkpoints of the cell cycle?

A

internal and external

39
Q

in order for the cycle to move forward how must sister chromatids be aligned during anaphase?

A

aligned down the metaphase plate

40
Q

when sister chromatids are properly aligned what is activated?

A

regulatory complex

41
Q

what does the regulatory complex activate?

A

separase

42
Q

what does separase do?

A

cleaves cohesins between sister chromatids (cuts them apart)

43
Q

what does separase protect?

A

the chromosomal content of daughter cells

44
Q

what 2 factors influence cell division?

A

physical and chemical

45
Q

what will stop cell division?

A

lack of an essential nutrient
(despite all other conditions favorable)

46
Q

what are growth factors made of?

A

proteins

47
Q

what do growth factors do?

A

released by cells in order to stimulate other cells to divide

48
Q

how many known types of grow factors are there?

A

> 50

49
Q

what is the process of the platelet derived growth factor (PDFG)?

A

tissue blended up
results in free fibroblasts
cells are transferred to culture vessels (one with PDFG, one without)
plate with PDFG are given the signal to divide

50
Q

why do only certain cells listen to this signal of PDFG?

A

or else everything in your body would start dividing

51
Q

the binding of PDFG to the receptor causes the cell to pass the G1 checkpoint and divide, why does this occur in the body?

A

to allow wound healing

52
Q

what is density dependent inhibition?

A

crowded cells will stop dividing if theres too much density

53
Q

in density dependent inhibition what is another factor that stops the cell cycle

A

cell surface protein binds to the counterpart on the adjacent cell and inhibits the growth of both cells

54
Q

what is anchorage dependence?

A

cell division will not occur unless cells are attached to a solid support

55
Q

what is an example of an anchor for anchorage dependence?

A

extracellular matrix or bottom of a container

56
Q

what is anchorage dependence controlled by?

A

plasma membrane proteins and the linked cytoskeleton

57
Q

what do cancer cells not exhibit?

A

density dependence inhibition or anchorage dependence

58
Q

what do cancer cells primarily do?

A

ignore normal signals
divide excessively (invading healthy tissues)

59
Q

in the absence of growth factors what happens to cancer cells?

A

continue to divide
may produce their own growth factors

60
Q

what are atypical checkpoints?

A

when cancer cells stop dividing at random points

61
Q

how are cancer cells immortal?

A

with unlimited nutrients they will divide indefinitely

62
Q

normal cells divide how many times before aging and dying?

A

20-50 times

63
Q

how does a mass of abnormal cells occur (tumor)?

A

if the immune system doesnt recognize the abnormal cell it will proliferate becoming a tumor

64
Q

if a tumor remains in one spot what is it considered?

A

benign

65
Q

if the tumor undergoes required changes and moves to another site what is it considered?

A

malignant (metastatic cancer)

66
Q

what causes cancer cells to be so successful?

A

collection of mutations

67
Q

chromosomes have what chromosome number?

A

unusual chromosome number

68
Q

what do cancer cells loose their ability to do because of this unusual chromosome number?

A

attach to surrounding cells and the extracellular matrix

69
Q

cancer cells may produce what that allow blood vessels to grow inward?

A

signaling molecules

70
Q

what can cancer cells be treated with?

A

high energy radiation and chemotherapy

71
Q

what does chemotherapy do?

A

selective toxicity
drugs are administered into the blood that target the cell cycle in actively dividing cells

72
Q

what are the side effects of chemotherapy?

A

healthy dividing cells are also targeted, making you weak

73
Q

why is high energy radiation more specific to cancer cells?

A

because they loose their ability to repair DNA damage

74
Q

what toxicity is less extreme? high energy radiation or chemotherapy?

A

high energy radiation
you get burns but toxicity isn’t as extreme, you can play hockey the next day1

BIOL 1020 (16 decks)

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