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Foundations test 3 > Epigenetics, Genomic Imprinting, and X-inactivation > Flashcards

Epigenetics, Genomic Imprinting, and X-inactivation Flashcards

1
Q

Epigenetics

A

Stable and heriable Changes in gene expression not related to DNA sequence changes

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2
Q

Epigenetic change brings

A

Altered expression levels

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3
Q

Mutated gene brings

A

Altered protein structure or altered protein level

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4
Q

Skewered X-inactivation

A

One allele may be more active than others…plays a role in x-linked recessive traits being expressed in females

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5
Q

Xist location

A

Gene located in the X-inactivation center of the X chromosome

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6
Q

Xist encodes

A

Long non-coding RNA that is expressed from the inactive X

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7
Q

Xist lncRNA

A

Coats the inactive X chromosome and facilitates its silencing

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8
Q

Most abundant DNA modification in our genome and what it is followed by

A

5mC…followed by a G…CpG dinucleotide

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9
Q

Other thing that happens to 5mC

A

Hydroxylated to become 5hmC

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10
Q

Enzymes responsible for methylating cytosine

A

DNMT…needs SAM-CH3…releases SAM

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11
Q

DNMT1

A

Maintenance methylase

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12
Q

DNMT3a and DMNT3b

A

De novo methylases

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13
Q

Methylation pattern is maintained through

A

Cell division

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14
Q

CpG dinucleotides found more often in

A

Promoters (CpG islands)

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15
Q

Most CpGs are

A

Methylated…EXCEPT for CpG islands which are typically unmethylated

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16
Q

Increase/decrease methylation effects

A

Increase - transcriptional silencing

Decreased - increased transcription

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17
Q

Chromatin composition

A

DNA , RNA, and porteins

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18
Q

Chromatin function and what is unique quality

A

Packages DNA but allows for replication, repair, and trascription

It is dynamic

19
Q

Nucleosome made of

A

DNA and histone

20
Q

Nuclease will

A

Digest linker DNA

21
Q

High concentration of salt will

A

Dissociated histone core and DNA

22
Q

Component parts of nucleosome

A

H2A, H2B, H3, H4

23
Q

Histone variation

A

Variant forms can be incorporated into nucleosome

24
Q

Histone mobilization

A

Enzymes can more nucleosomes

25
Q

Histone modification

A

Multiple types exist

26
Q

Histones are moved by

A

ATP dependent process that is often facilitated by TFs and co-regulators

27
Q

Nucleosome free regions are

A

More accessible to other proteins like TFs and RNA polymerase…example is promoter…result of histone mobilization

28
Q

Acetylation and deacetylation of histones

A

Acetylation leads to Increase gene expression and vice versa
HATs, p300/CBP acetylate
HDACs deacetylate

29
Q

Histone code is

A

Dynamic and has memory

30
Q

Genomic imprinting

A

Parent-of-origin expression of autosomal genes…imprint maintained throughout life but erased and reestablished from one gen to next…associated with DNA methylation

31
Q

Paternal and maternal autosomal genes are

A

Both required for normal development…NOT equally expressed

32
Q

Many imprinted genes control

A

Embryonic growth and brain fevelopment

33
Q

H19 codes and regulation

A

lncRNA (not for a protein)….only female transcribed…paternal is imprinted (silent)

34
Q

Igf2 encodes and regulation

A

Fetal growth factor…only male derived…maternal is imprinted

35
Q

Mechanism of H19 and IGF2

A

Maternal - CTCF bound to insulator so H19 is on

Paternal - insulator and H19 heavily methylated so IGF2 is on

Enhancer helps transcirbe both

36
Q

Transcriptionally active DNA charactersitics

A

Open chromatin
Hypomethylated DNA
Histones acetylated

Transcriptionally asilent is the opposite

37
Q

Barker Hypothesis

A

Reduced nutrients during fetal hrowth leads to epigenetic changes to maximize energy utility which leads to chronic conditions later in life

38
Q

Oncogenes activated by

A

Loss of DNA methylation

39
Q

TUmor suppressors silenced by

A

DNA methylation

40
Q

Mutation of imprinted genes can lead to

A

Prader-willi and Angelman’s syndrome

41
Q

When are x-chromosomes inactivated in females?

A

16-32 cell stage…once established, it is maintained throughout all progeny of that cell

42
Q

Xist located in

A

X-inactivation center

43
Q

Sole methyl donor for DNA methylation

A

S-adenyl methionine (SAM)

44
Q

How is methylation passed during replication?

A

During DNA replication, will have a hemimethylated strand until maintenance methylase comes in an methylates so that pattern is maintained

(DNMT1)

Foundations test 3 (15 decks)

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