Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Gene regulation > Genomic imprinting 2 > Flashcards

Genomic imprinting 2 Flashcards

1
Q

Why can women suffer from haemophilia?

A

The mutant x chromosome may be activated and the normal one inactivated

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

Four stages of inactivation?

A

Establishment, maintenance, reading, erasure

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

Three stages of x inactivation in diploid cells?

A

Counting, choice, stabilisaiton

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

Why is the counting phase necessary in x inactivation?

A

Must inactivate all X chromosomes except 1 (might have 3 and so need to inactivate 2)

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

What happens regarding the progeny of a cell that has done the x inactivation?

A

They will all have the same x chromosome(s) inactivated and the same x chromosome activated

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

Which gene is the x inactivation centre near?

A

Xist

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

Which gene is the x inactivation centre opposite?

A

Tsix

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

How far on either side of the Xist gene is the critical region for x inactivation?

A

150kB

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

What happens if there is a deletion or mutation in the x inactivation centre?

A

That x chromosome does not become inactivated

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

What happens if the choice component of the x inactivation centre is put into other regions of the genome?

A

They can inactivate other genes

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

What type of RNA is Xist transcribed into?

A

lncRNA

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

What type of RNA is Tsix transcribed into?

A

lncRNA

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

What is the locational relationship between Tsix and Xist regarding their transcription?

A

They are expressed in opposite orientation to one another

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

How much of Tsix and Xist are produced prior to inactivation?

A

Very low levels

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

Role of Tsix?

A

Reduce Xist expression

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

What role does Xist have in gene activation?

A

a gene with high levels of Xist expression is an inactive gene

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

What happens to Tsix expression on the active X once the inactive X is turned off?

A

Tsix is no longer required

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

Why is Tsix no longer required once inactivation has occured?

A

Epigenetic mechanisms lock the inactive X into being silenced

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

Which stage of X inactivation doesn’t require Xist?

A

Maintainance

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

X inactivation state in pluripotent embryonic stem cells?

A

Both Xs are active

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

Tsix and Xist expression in embryonic stem cells?

A

Both are expressed

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

What happens to Xist and Tsix expression in stem cell differentiation?

A

One chromosome expresses a lot more Xist

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

What does Xist RNA do to the inactive X chromosome?

A

Coats it

24
Q

Sex of tortoiseshell cats?

A

Always female

25
Q

What are DMRs?

A

Differentially methylated regions (where one allele of a gene on one chromosome is more/less methylated than the sister allele on the other chromosome)

26
Q

Full “lollipop” on gene expression diagram?

A

Methylated gene

27
Q

Hollow “lollipop” on gene expression diagram?

A

Non-methylated gene

28
Q

When do primordial germ cells lose their methylation?

A

When they are migrating to the genital ridge

29
Q

What are the most hypomethylated cells?

A

Primordial germ cells on their way to the genital ridge

30
Q

What helps imprints to be maintained after fertilization and ensures they won’t be erased?

A

Maternal zygotic factors

31
Q

Role of ZFP57?

A

Maintains maternal imprints

32
Q

Role of Pgc7 (stella, DPPA3)?

A

Protecting maternal imprints from demethylation

33
Q

How do maternal zygotic factors ensure imprinting is maintained?

A

Bind to DNA at specific methylated sequences (high preference for imprinted regions) and they stop TET enzymes from demethylating the imprinted regions

34
Q

What are the three ways by which a TF can “read” an imprint and transcribe from only one parental allele?

A

Differential promoter selection
Differential inhibition by noncoding RNA
Differential boundaries

35
Q

Which level of methylation makes it easier for a TF to bind?

A

Low levels of methylation

36
Q

How does noncoding RNA expression work in imprinting?

A

If a noncoding RNA is expressed (low methylation of it) then it can affect a downstream gene and repress that gene. If a noncoding RNA isnt expressed (high methylation) then it cant affect a downstream gene and so that gene is active

37
Q

What is cotranscriptional interference?

A

Two polymerases on either side in opposite directions cant squeeze past one another, so interference with transcription happens

38
Q

What can noncoding RNA do regarding bringing in other molecules?

A

It can bring in repressive promoters, histone methylation etc to act as a scaffold to create a silencing effect

39
Q

Where are insulators spaced in the genome?

A

40kB-100kB

40
Q

How does CTCF cause a silencing effect?

A

It has zinc fingers which wind the DNA into a knot so their genes cannot be accessed by TFs or other regulatory mechanisms

41
Q

What level of methylation is required for CTCF binding?

A

Unmethylated DNA

42
Q

Which sex’s allele expresses IGF2?

A

Paternal

43
Q

Which sex’s allele expresses H19?

A

Maternal

44
Q

What type of RNA is H19?

A

noncoding

45
Q

Role of H19?

A

Suppresses IGF2

46
Q

What type of gene is IGF2?

A

Growth factor

47
Q

Why are beckwith wiedermann syndrome affected people larger than average?

A

They express too much IGF2

48
Q

What happens, regarding CTCF, if an imprinting control region is methylated?

A

CTCF cannot bind

49
Q

What happens if CTCF isnt bound to an imprinted control region?

A

A gene can access its enhancer on the other side of the ICR, leading to expression of the gene

50
Q

How many zinc fingers does CTCF have?

A

7

51
Q

Role of cohesin in combination with CTCF?

A

Can hold sister chromatids together, or create a boundary in the middle of a chromatid

52
Q

Role of KCNQ1OT1?

A

Coating the chromosome in the area where it acts, preventing those genes from being expressed

53
Q

Effect of uniparental dispmy?

A

Both maternal and paternal chromosome look like they are a paternal chromosome (appears you have two paternal chromosomes)

54
Q

Origins of uniparental disomy?

A

Trisomy rescue, monosomy rescue

55
Q

Trisomy rescue?

A

Disomic oocyte (2 egg chromosomes instead of 1) and 1 haploid sperm–> the two egg chromosomes are what are passed onto the offspring instead of 1 egg and 1 sperm. Leads to maternal heterodisomy

56
Q

Monosomy rescue?

A

Nullisomic oocyte (0 egg chromosomes) so haploid sperm duplicates to ensure there is enough chromosomes. Leads to paternal isodisomy

57
Q
A

Gene regulation (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions