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Biochem IV > cell cycle > Flashcards

cell cycle Flashcards

1
Q

What three cell-cycle phases make up interphase?

A

G1, S and G2

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2
Q

What happens during S phase?

A

DNA is replicated

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3
Q

What stage are differentiated cells in?

A

G0

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4
Q

What cyclin/CDK complex is present in M phase?

A

A/CDK1 and B/CDK1

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5
Q

What cyclin/CDK complex is present in Mid G1 phase?

A

D/CDK4 and D/CDK6

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6
Q

How are cyclins degraded?

A

ubiquitin dependent proteolysis

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7
Q

Genes that respond quickly to an addition of a growth factor are called?

A

early response genes

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8
Q

What is an important early response gene?

A

c-Fos

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9
Q

What three genes transcribe the delayed response genes?

A

c-Fos, c-Jun and c-Myc

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10
Q

A ligand binding causes what two processes to happen to the receptor?

A

dimerization

autophosphorylation of the receptor

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11
Q

What does Sos promote?

A

exchange of GDP for GTP on Ras

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12
Q

What is another name for ERK?

A

MAP kinase

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13
Q

Which kinase of the MAP kinase pathway can enter the nucleus?

A

MAP Kinase

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14
Q

The activation of MAP kinase stimulates txn of what gene?

A

c-Fos

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15
Q

What process leads to progression through the restriction point?

A

increasing c-Fos txn

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16
Q

Which cyclins and CDKs are part of the delayed-response genes?

A

mid G1 and late G1

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17
Q

The retinoblastoma protein is phosphorylated by what cyclin/CDK?

A

cyclin D and CDK 4/6

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18
Q

E2F proteins are proteins of what response?

A

delayed response

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19
Q

E2F proteins activate genes required for what?

A

DNA replication

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20
Q

What cyclins and CDK are activated by E2F?

A

cyclins E and D

CDK2

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21
Q

What is the role of E2F proteins when bound to Rb?

A

repressors of txn

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22
Q

What two complexes does Rb bind that inhibit gene txn?

A

HDAC and methylase complexes

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23
Q

What causes dissociation of Rb from E2F?

A

phosphorylation by cyclin D and CDK 4/6

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24
Q

What product of E2F activation can also activate Rb?

A

E-CDK2

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25
What type of proteins inhibits cyclin D association with CDK4/6? What effect does this have?
INK4 proteins inhibits cell growth
26
What protein is a member of the INK4 protein class?
p16
27
What is the best understood inhibitor of A-CDK2?
p27-KIP1
28
What phosphorylates p27-KIP1?
late G1 cyclins
29
What does phosphorylation of p27-KIP1 entail?
polyubiquitination subsequent activation A-CDK2
30
What components of replication does CDK-2 phosphorylate?
origin of replication components
31
What is the most important driver of the events leading up to mitosis?
CDK1
32
How is CDK1 activated?
de-phosphorylation
33
What is the function of cohesin?
to hold sister chromatids together at the centromere
34
What complex degrades cohesion?
anapahse promoting complex
35
What complex polyubiquitinates cyclin A and B?
anaphase promoting complex
36
What checkpoint does ATM regulate?
G2/M
37
What is the function of ATM?
to detect if DNA synthesis is still in process
38
What needs to happen to CDK1 for the cell to enter mitosis?
dephosphorylation
39
Ultimately, what does ATM prevent?
inhibition of CDK1 dephosphorylation
40
ATM is always active as long as what are present?
replication forks
41
What event activates ATM?
double stranded DNA breaks
42
What activates ATR?
DNA damage caused by UV radiation
43
Are CDK1 and CDK2 active in a phosphorylated or dephosphorylated state?
dephosphorylated
44
What effect do ATR/ATM have on CDK1 and CDK2 phosphorylation states?
inhibit their dephosphorylation and subsequent activation
45
What does ATR/ATM activation do to p53?
Phosphorylates it
46
What does phosphorylation of p53 result in?
stabilization and increase in its levels
47
What does p53 do to p21-CIP1?
activates it
48
What is the function of p21-CIP1?
inhibits the action of cyclin/CDK1 and cyclin/CDK2
49
Ataxia-telangiectasia patients have a mutated copy of what protein?
ATM
50
What type of DNA damage are patients with ataxia-telangiectasia?
double-stranded DNA breaks
51
Where does chromosome condensation occur in the early stages of apoptosis?
around the periphery of the nucleus
52
What happens to cell size during apoptosis? What is this called?
shrinks cytoplasmic condensation
53
What is the intrinsic pathway of apoptosis?
activation of p53
54
What two cellular ligands are implicated in the external pathway of apoptosis?
Tumor necrosis factor (TNF) Fas ligand
55
What produces TNF?
macrophages
56
What two cell types produce Fas ligand?
NK cells and T-lymphocytes
57
What enzymatic activity do caspases possess?
cysteine aspartate protease activity
58
p53 activates apoptosis through which three proteins?
PUMA, BID and BAX
59
What is the function of BAX? What does this release?
to form a channel in the outer mitochondrial membrane cytochrome c
60
What protein inhibits BAX? What proteins activate BAX?
bcl-2 = inhibit PUMA and BID = activate
61
Upon entry into the cytosol, what does cytochrome c bind to?
Apaf-1
62
What does binding of cytochrome C do to apaf-1?
induces its oligomerization
63
Which caspases are activated by Apaf-1?
caspase-9 and caspase-3
64
What is the role of caspase-9? What is the role of caspase-3?
caspase-9 = initiator caspase-3 = executioner
65
What is the function of Sos?
to promote exchange of GDP for GTP on Ras
66
What does increasing the transcription of c-Fos do?
pushes the cell through the restriction point
67
INK4 proteins function to do what?
inhibit the association of cyclin D with CDK 4 and 6
68
What is the function of cohesion? What promotes the dissolution of cohesin?
hold sister chromatids together anaphase promoting complex
69
The anaphase promoting complex polyubiquitinates which cyclins?
A and B
70
What does ATM detect?
replication forks
71
What is the purpose of ATM?
to prevent M phase before G2 phase is complete
72
Ataxia telangiectasia is caused by mutations to what protein?
ATM
73
What cell produces tumor necrosis factor?
macrophages
74
What cell produces Fas ligand?
natural killer cells
75
What is the early response gene?
c-Fos
76
What two proteins join Fos to transcribe the delayed response genes?
Jun and Myc
77
What are the delayed response genes?
Mid G1 and Late G1 cyclins and CDKs
78
ERK stimulates the txn of what gene?
Fos
79
What protein phosphatase is activated at the end of DNA replication?
Cdc25c
80
The anaphase promoting complex leads to the destruction of what cyclins?
cyclin A and cyclin B
81
What does ATM recognize?
replication forks
82
What protein component does ATM inhibit?
Cdc25C
83
When ATM/ATR sense DNA damage, what protein do they phosphorylate?
p53
84
What protein does p53 upregulate?
p21-CIP1
85
What CDKs does p21-CIP1 inhibit?
CDK1 and CDK2
86
Patients with ataxia-telangiectasia posses a mutated version of what protein?
ATM
87
MAP kinase increases the txn of what DNA binding protein?
c-Fos

Biochem IV (6 decks)

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