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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
Where does positive feedback of MFP originate?
cdc25
26
What feedback does wee1 produce?
negative feedback to MPF
27
What are the CDK inhibitor families?
Cdk Inhibitory Proteins (CIP), Inhibitor of cdk4 (INK)
28
Which proteins belong to CIP?
p21, p27, p57
29
Which proteins belong to INK?
p16
30
How do CIPs initiate DNA damage responses?
DNA damage caused ATM kinase to phosphorylate p53. MDM2 ubiquintatin ligase targetting inhibited so p21 transcription activated. Cells arrest in G1.
31
What does p53 control?
apoptosis. mutation results in cancer
32
Which stimuli act on G0 cells?
EGF, PDGF for RTKs; GPCRs for cAMP/PKA for nuclear transcription factors c-Myc, c-Jun, c-Fos
33
What is apoptosis?
Programmed cell death in an orderly and controlled manner with a defined programme
34
What is TUNEL assay?
Fluorescent labelling of DNA fragment termini
35
What does Anexin V label?
Apoptotic phospholipid membrane receptors for FITC quantification
36
How can apoptosis be observed?
Anexin V FITC, TUNEL, DNA ladders, cell morphology, western blotting of caspases
37
When are early response genes overactivated?
cancer
38
Are early response genes maintained?
No, they decline after activating expression of delayed response genes
39
Does synthesis of early response genes require proteins?
No
40
What are caspases?
Cys-catalysed ASP-targetting proteASES
41
How are caspases activated?
Cleavage of N terminal regulatory domain, heterodimerisation
42
What are the 2 classes of caspases?
Initiator (8&10, 9), executioner (7&3)
43
Which initiator caspases are activated by the intrinsic pathway?
9
44
Which initiator caspases are activated by the extrinsic pathway?
8 & 10
45
What does c-FLIP do?
Inhibit caspase 8 activating executioners
46
When is c-FLIP overexpressed?
In death-ligand resistant cancers
47
How are caspases activated?
Cleavage of N terminal regulatory domain, small and large domains; heterodimerisation
48
Examples of intracellular/intrinsic decision pathway
p53 upregulation, DNA damage, hypoxia, withdrawal of survival factors, UV radiation
49
Which death receptors are involved in extrinsic exectution phase?
TRAIL acts on death receptors 4/5 FasL on Fas TNFalpha on TNFR-1
50
What are the 2 phases of apoptosis?
decision and exectution
51
What is the extrinsic exectution pathway?
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
How do cells become resistant to extrinsic death ligands?
soluble or membrane bound decoy receptors, intracellular signalling inhibitors
53
What is intrinsic execution pathway?
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
Which pathway does BCL-2 family operate in?
Instrinsic
55
What does BCL BH3 do?
Block BH1234
56
What does BCL family BH1234 do?
Block aggregation and pore formation of BH123
57
Which molecules are BCL BH123?
pro-apoptotic
58
What action are BCL BH1234?
antiapoptotic
59
Which action is BCL BH3?
proapoptotic
60
Which BCL proteins does p53 upregulate?
Bax (B) and Puma (C) to promote apoptosis
61
Which pathway doe IAPs block?
Apoptotic intrinsic pathway by binding caspases
62
How are IAPs counteracted?
anti-IAPS released through BH123 pores
63
How long are telomeres?
12kb/ 2 thousand repeats
64
What is the sequence of telomeres?
TTAGGG
65
How long is the telomere 3' overhang?
100-200nt
66
What is the purpose of the telomere 3' overhang?
forms T loop to bind proteins to pair sister chromatids and project against shortening and entanglement
67
How many bases are lost from a telomere in mitosis?
100bp
68
Where does telomerase act?
germline and stem cells, cancer and unicellular eukaryotes
69
How does telomerase act?
Removal of primer, TERC template binds for TERT synthesis. Ratchet mechanism
70
What does TERC consist of?
451nt AAUCCC
71
What does shortening of telomeres cause?
Senescence-aging and death after ~ 50 divisions

Health and Disease: Genes (6 decks)

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