Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BMS247 Stem Cells > L14/15 - Check Point Controls > Flashcards

L14/15 - Check Point Controls Flashcards

(102 cards)

Start Studying
1
Q

Getting genetic material from one cell to the daughters depends on

A

Faithful replication of a cells geneome

Proper allocation of the cells DNA to the daughter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Cells are only allowed to proceed with the cell cycle if …

A

If the pre-requisites have been completed sucessfully

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens if the pre-requistes have not been met

A

Halt to further advance until the problems have been adressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The monitoring of cells are known as

A

Check point controls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the result of a cells genome being in need of repair

A

The cell will not be able to enter S phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What hapeens if DNA is damaged

A

Replication will be paused

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens if the G2/M checkpoint if there is DNA damage

A

Entry into M phased is blocked

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When is a cell allowed to enter anaphase

A

When all of its chromosomes are properly alligned on the mitotic spindle during metaphase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What monitors each step of the cell cycle

A

Surveillance mechanisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens if the pre-requiste steps havent been met

A

Halt to further advance until problems have been adressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What must be the state of the genome for the cell to be able to proceed into S phase

A

Genome is not in any need of repair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When may DNA replication be paused

A

If there is damage to the DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

If cell needs to pause replication of the DNA what is the effect of this on the duration

A

Can double the time taken for the genome to be replicated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What must be completed for a cell to proceed through G2 and M phase

A

Replication of the DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

M phase entry will be blocked if

A

DNA damaged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

A cell is not permitted to enter anaphase until ….

A

All of its chromosomes are properly assembled on the spindle during metaphase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does the increased mutability of the genome provide cancer cells with a prolfierative advantage

A

Incompatible with normal cell cycle progression

Checkpoint controls block advance through the cell cycle if DNA has been damaged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

In addition to activating oncogenes and inactivating tumour supressor genes what else may be inactivated

A

One or more check point controls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

pRB ….

A

Blocks advance through the cell cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the molecular goveronor of the R point

A

RB (retinoblastoma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Cells are only able to go through the R point only if …

A

pRb becomes hyperphosphorylated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

pRb phosphorylation is governed by

A

Components of the cell cycle clock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

pRb becomes phosphorylated in what phase …

What complex mediates this

A

D-CDK4/6

Early and mid-G1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Levels of what cyclin increase at the R point

A

E

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What complex mediates the hyperphosphorylation of pRB
E-CDK2
26
Unphosphorylated/hypophosphorylated pRB is able to bind to
E2F
27
When hyperphosphorylated what happens to Rb association with E2F
Dissociates
28
Describe the effect of pRb binding to E2F, and when does this occur
In early and mid G1 - pRb binds to E2F preventing the trasncription of E2F dep genes
29
pRb becomes hyperphosporylated at the R point - effect of this
Release of E2F | Transcription of genes which mediate the transition between G1 ans S phase
30
Why is the activity of E2F shortlived
Cyclin A-CDK2 inhibits the transcritpional activity of E2F - which is then tagged with ubiquitin and is degraded
31
Cyclin E transcription promotes driving of
E2F
32
What is the purpose of the spindle checkpoint
If a chromosome has been misplaced the cell cycle will be paused allowing time for the stray chromosome to be captured
33
Progression to anaphase controlled by
The anaphase promoting complex
34
APC/C
Anaphase promoting complex
35
When is the APC/C active
When all of the chromosomes are aligned on the spindle
36
APC/C is a
Ubiquitin ligase
37
What does APC/C ubiquitinate
Securin - causing the degradation of securine
38
What is securin bound to
Separase
39
When does separase become active
When securin has been ubiquitinated and degraded - and separase has been released from its complex with securin
40
What is the role of separase once it become active
Breaks the links between the 2 sister chormatids
41
How does separase break the links between the 2 sister chromatids
Degrades cohesin
42
What is checked for at the G2/M transition
Integrity and fidelity of the DNA | DNA replication
43
DNA damage checkpoints are active when
G1, S, G2
44
What protein mediates cell cycle arrest when there is a double strand break
ATM
45
What protein mediates cell cycle arrest when there is a single stranded break
ATR
46
P53 is a
Tumour suppressor gene
47
What molecular function does P53 have
It is transcription
48
What genes are regulated by p53
Genes which mediated growth suppression, apoptosis and repair
49
What is the target gene of P53
P21(Cip1)
50
P21 is a
CKI
51
What does P21 inhibit
E-CDK2, A-CDK2, A-CDC2 and B-CDC2
52
Describe the normal mechanism of function of P53 in response to dNA damage
P53 detects DNA damage and activates transcription of target genes - Cells halt at G1 checkpoint - DNA repair activated - Apoptosis
53
The underlying concept in P53 in response to DNA damage
Damaged DNA is not passed on to progeny
54
An effect of a mutation in P53 means that
P53 is unable to bidn to the DNA so can't transcribe any of the genes
55
What is the outcome of mutation in p53
Damaged DNA is passed on
56
What is anoikis
Cell detachement induced apoptosis
57
What is the point of anokisis
A self defence stratergt that organsisms use to eliminate cells in inapproporiate locations
58
Myc protein governs
The deicsion of proliferation vs differentiation
59
More that 70% of human tumours overexpress
A member of the myc family
60
What are the members of the myc family
C/N/L myc
61
How many ways of myc inductions
3
62
Describe breifely the three ways of myc induction
Expression dirven by a normal promoter but gene is amplifed due to an abnormal copy number Chromosomal translocation - puts myc under control of a foreign promoter Pro-virus integration causes insertional mutagenesis
63
What type of molecule is myc
bHLH TF
64
Describe the strucutre of myc
basic DNA binding domain followed by an amino acid sequence forming an alpha helix, a loop and then a second helix
65
Myc forms ...... which then becomes associated with gene promoters
Dimers
66
What is the effect of myc-max on proliferation
Promotes
67
What is the effect of myc-max on differentiation
Inhibits
68
What is the effect of mad-max on proliferation
Inhibition
69
What is the effect of mad-max on differnetiation
Promotes
70
Mad is expressed more highly in what cells
Differentiating cells
71
The higher levels of expression of Mad in differentiating cells means
Mad able to dispalce myc from its complex with Max
72
What does myc/max also regulate
The expression of key componenets of the celll cycle including C2 and CDK3 Also has an effect on E2F transcription facotrs
73
What is the effect of myc-miz1
Repression of CKI liberating E/CDK2 complexes from inhibitio n
74
What is the effeect of myc-miz1 on P27
Deg
75
Describe an experimental set up of the Myc oncoprotein
Myc expressed as a fusion protein with oestrogen receptor | Addition tamoxifen or oestrogen (ligand) drives myc translocation to the nucleus
76
What is the effect of adding tamoxifen to cells that are in G0 in the absence of any growth factors
tamoxifen addition induces re-entry back into G1 and S phase
77
The conclusion of the 'powers of myc protein'
Myc is acting on its own and is able to lift all of the constraints on proliferation
78
What is TGF-B involved in
``` Growth Differentiation Apoptosis Homeostasis Other cellular functions ```
79
What receptor does a TGF-B ligand bind to
Binds to the type II receptor which then recruits and phosphorylates the type 1 receptor
80
Type 1 receptor phosphorylates
Receptor regulated SMADs
81
What can happen once the type I receptors has phsophrorylated the R-SMADs
Can then bind to the coSMAD - SMAD4
82
TGF-B strongly increases levels of ..... This causes .... End result of this is that ....
Levels of P15 Inhibition of C-CDK4/6 Cells are unable to reach the R point
83
TGF-B weakly induced
Levels of P21
84
TGF-B uses ____________ to block progression through
2 CDK inhibitors (p15 and p21) to block progression through G1
85
TGF-B inhibits the expression of
Myc
86
Is TGF-B still able to inhibit the expression of myc in tumours
No
87
TGF-B _________ the activty of Myc It also stops the binding of _______ to CKI promoters
Counteracts Myc
88
What are two examples of how cancer cells inactivate TGF-B signalling
Mutations in SMAD4 Mutations in colon cancers
89
TGF-B inhibits cell cycle progression by controlling pRb function How do cancer cells get aorund this
Deregulation of the pRB pathway
90
What are the mechanims of deregulation of the pRB pathway
Inactivation of Rb through mutations Expression of very high levels of cyclin D1 Downregulation of INK4 proteins - inapproproate activation of pRb Mutations in CDK4 gene - no longer able to bind the INK4 familty
91
P53 is a TF for genes
Regulating cell growth and apotosis
92
P53 is the most ...
Freuqentyl mutated gene in human cancers
93
Where do mutations in p53 tend to occur
In the DNA binding domain
94
Control of p53 levels is through _____
Mdm2
95
Describe how p53 is controlled by Mdm2
Ubiquinated by Mdm2 and degraded by the proteaosome in the absence of stress
96
When does Mdm2 cause the degradation of p53
When there is no stress
97
What must happen when there is stress or damage
P53 must be protected from degradation
98
What is the mechanism for the protection of P53
Phos of P53 blocks Mdm2 binding and this is mediated by ATM/ATR/Chk2
99
What mediates all 3 of the DNA damage checkpoints
P53
100
Describe what must happen to P53 when there is stress of damage
P53 must be protected Phos of P53 blocks Mdm2 binding ATM phos Mdm2 --> inactivating Mdm2 Rapid increase in p53 levels
101
What is the effect of mitogenic and cell curvival signals
Induction of Mdm2 Phosphorylation induced activation of mdm2 (at a different residue P53 is degraded in the proteasome Supression of P53 levels
102
How does p53 cause cell cycle arrest
By upregualting P21 which inactivates cyclin-CDK complexes

BMS247 Stem Cells (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions