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Health and Disease: Genes > Blair Cell Cycle > Flashcards

Blair Cell Cycle Flashcards

1
Q

Where do quiescent cells reside?

A

G0/G1 phase

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2
Q

How long is DNA synthesis phase?

A

S phase, 10 hours

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3
Q

Which cell phase is most manipulative?

A

G1 phase ~9 hours

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4
Q

Which cells are slower through G1 phase: Stem cells or differentiated cells?

A

Stem (primary) cells

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5
Q

What does colemid do to allow study?

A

binds mictrobules to inhibit mitosis and enrich M phase

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6
Q

Which cell phase is visible under a light microscope?

A

M phase

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7
Q

What do hydroxyurea and thymidine inhibit?

A

Polymerase in S phase

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8
Q

Which base analogues can S phase be detected with?

A

bromodeoxyuridine replaces thymidine detected with anti-BUdR antibodies

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9
Q

Which phases cannot be separated by FACS?

A

G2 and M (4n diploid genome)

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10
Q

Where were cdc genes discovered?

A

yeast cells

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11
Q

Which transition does MPF control?

A

G2/M

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12
Q

Which MPF component is constitutively expressed?

A

cdk1

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13
Q

What is the cdc2 analogue in mammals?

A

cdk1

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14
Q

What is MPF made up from?

A

Cyclin B regultory subunit and cdk1

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15
Q

What does wee1 do to cdk1?

A

phosphorylate Y15 to block ATP binding

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16
Q

Which proteins have antagonistic action on Y15?

A

wee1 and cdc25

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17
Q

What does cak do to cdk1?

A

primes in G2 by phosphorylation of T161 for substrate binding.

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18
Q

What does active cdk1 do?

A

phosphorylates condensin for chromatin condensation, spindle formation, ER and golgi fragmentation, lamina breakdown

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19
Q

What does anaphase promoting factor do?

A

E3 ubiquitin ligase for degradation of cyclin B after mitosis has started, degrades securin to separate sister chromatids

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20
Q

Which cdk/cyclin complex controls G1?

A

cdk4/cyclin D

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21
Q

Which checkpoint is for integrity of DNA?

A

G1/S by cdk2/cyclin E. E2F tf bound by Rb and HDACs for repression of transcription, released by Rb hyperphosphorylation in late G1. Transcription of S phase complex genes cdk2/cyclin A

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22
Q

Which genes control G1/S transition?

A

cdk2/cyclin E

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23
Q

Which genes control S phase checkpoint?

A

cyclin A/ cdk2 transcribed by E2F

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24
Q

Where was MPF discovered?

A

sea urchins

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25
Q

Where does positive feedback of MFP originate?

A

cdc25

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26
Q

What feedback does wee1 produce?

A

negative feedback to MPF

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27
Q

What are the CDK inhibitor families?

A

Cdk Inhibitory Proteins (CIP), Inhibitor of cdk4 (INK)

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28
Q

Which proteins belong to CIP?

A

p21, p27, p57

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29
Q

Which proteins belong to INK?

A

p16

30
Q

How do CIPs initiate DNA damage responses?

A

DNA damage caused ATM kinase to phosphorylate p53. MDM2 ubiquintatin ligase targetting inhibited so p21 transcription activated. Cells arrest in G1.

31
Q

What does p53 control?

A

apoptosis. mutation results in cancer

32
Q

Which stimuli act on G0 cells?

A

EGF, PDGF for RTKs; GPCRs for cAMP/PKA for nuclear transcription factors c-Myc, c-Jun, c-Fos

33
Q

What is apoptosis?

A

Programmed cell death in an orderly and controlled manner with a defined programme

34
Q

What is TUNEL assay?

A

Fluorescent labelling of DNA fragment termini

35
Q

What does Anexin V label?

A

Apoptotic phospholipid membrane receptors for FITC quantification

36
Q

How can apoptosis be observed?

A

Anexin V FITC, TUNEL, DNA ladders, cell morphology, western blotting of caspases

37
Q

When are early response genes overactivated?

A

cancer

38
Q

Are early response genes maintained?

A

No, they decline after activating expression of delayed response genes

39
Q

Does synthesis of early response genes require proteins?

A

No

40
Q

What are caspases?

A

Cys-catalysed ASP-targetting proteASES

41
Q

How are caspases activated?

A

Cleavage of N terminal regulatory domain, heterodimerisation

42
Q

What are the 2 classes of caspases?

A

Initiator (8&10, 9), executioner (7&3)

43
Q

Which initiator caspases are activated by the intrinsic pathway?

A

9

44
Q

Which initiator caspases are activated by the extrinsic pathway?

A

8 & 10

45
Q

What does c-FLIP do?

A

Inhibit caspase 8 activating executioners

46
Q

When is c-FLIP overexpressed?

A

In death-ligand resistant cancers

47
Q

How are caspases activated?

A

Cleavage of N terminal regulatory domain, small and large domains; heterodimerisation

48
Q

Examples of intracellular/intrinsic decision pathway

A

p53 upregulation, DNA damage, hypoxia, withdrawal of survival factors, UV radiation

49
Q

Which death receptors are involved in extrinsic exectution phase?

A

TRAIL acts on death receptors 4/5
FasL on Fas
TNFalpha on TNFR-1

50
Q

What are the 2 phases of apoptosis?

A

decision and exectution

51
Q

What is the extrinsic exectution pathway?

A

Ligand binds, homotrimerisation, recruitment of FADD through death domain, acts as an adapter to recruit caspases 8 & 10 through Death Effector Domain to assemble DISC and cleave/ activate caspases

52
Q

How do cells become resistant to extrinsic death ligands?

A

soluble or membrane bound decoy receptors, intracellular signalling inhibitors

53
Q

What is intrinsic execution pathway?

A

Stimulus releases cytochrome C from mitochondria. Binds Apaf1: hydrolysis of dATP and activation of CARD domain. dADP-dATP exchange triggers assembly of apoptosome. CARD domain recruits propase 9 inititator.

54
Q

Which pathway does BCL-2 family operate in?

A

Instrinsic

55
Q

What does BCL BH3 do?

A

Block BH1234

56
Q

What does BCL family BH1234 do?

A

Block aggregation and pore formation of BH123

57
Q

Which molecules are BCL BH123?

A

pro-apoptotic

58
Q

What action are BCL BH1234?

A

antiapoptotic

59
Q

Which action is BCL BH3?

A

proapoptotic

60
Q

Which BCL proteins does p53 upregulate?

A

Bax (B) and Puma (C) to promote apoptosis

61
Q

Which pathway doe IAPs block?

A

Apoptotic intrinsic pathway by binding caspases

62
Q

How are IAPs counteracted?

A

anti-IAPS released through BH123 pores

63
Q

How long are telomeres?

A

12kb/ 2 thousand repeats

64
Q

What is the sequence of telomeres?

A

TTAGGG

65
Q

How long is the telomere 3’ overhang?

A

100-200nt

66
Q

What is the purpose of the telomere 3’ overhang?

A

forms T loop to bind proteins to pair sister chromatids and project against shortening and entanglement

67
Q

How many bases are lost from a telomere in mitosis?

A

100bp

68
Q

Where does telomerase act?

A

germline and stem cells, cancer and unicellular eukaryotes

69
Q

How does telomerase act?

A

Removal of primer, TERC template binds for TERT synthesis. Ratchet mechanism

70
Q

What does TERC consist of?

A

451nt AAUCCC

71
Q

What does shortening of telomeres cause?

A

Senescence-aging and death after ~ 50 divisions

Health and Disease: Genes (6 decks)

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