Lecture 10 - Epigenetics Flashcards

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1
Q

epigenetics can be defined as: ……. changes in gene expression that are……. a consequence of change in ….. sequence

A

heritable
not
DNA

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2
Q

how can epigenetics be modified, 2 ways?

A

environmentally and pharmacologically

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3
Q

name 3 markers of epigenetics

A

DNA methylation, histone modifications and miRNA

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4
Q

to which position is a methyl group added to the cytosine ring in DNA methylation?

A

position 5

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5
Q

name the 3 DNA methyltransferases involved in the catalysis of DNA methylation

A

DNMT1, 3a, 3b

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6
Q

after the addition of a methyl group to the cytosine ring of DNA in DNA methylation what is cytosine’s new name?

A

5-methylcytosine

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7
Q

at which dinucleotides does DNA methylation only ever occur at?

A

CpG

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8
Q

true or false, the pattern of DNA methylation is not stably inherited?

A

false, it is

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9
Q

what percentage of CpGs are methylated?

A

70%

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10
Q

true or false, the genome is CpG poor?

A

true

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11
Q

which version of cytosine is prone to mutation?

A

J-cytosine

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12
Q

in transcriptional repression within DNA methylation, which 2 molecules bring in large complexes to compact chromatin and prevent transcription factors binding?

A

MBD3, MBD2

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13
Q

where in the body and also on which type of cells is there lots of non CpG methylation?

A

brain, ES cells

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14
Q

is hydroxy methylation copied by DNMT1?

A

no

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15
Q

name the 4 possible histone modifications

A

acetylation, methylation, phosphorylation, ubiquitination

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16
Q

in histone modification, acetylation can do which 3 things?

A

activation, decompaction of chromatin, permissive

17
Q

is methylation in histone modifications permissive or non permissive when associated with K9-H3, K27-H3?

A

non-permissive

18
Q

name the 3 roles of methylation in histone modification on K9-H3 and K27-H3?

A

inactivation, compaction, non-permissive

19
Q

name the 2 sets of residues upon which methylation of histones can occur causing INACTIVATION

A

K9-H3
K27-H3

20
Q

name the set of residues upon which methylation of histones can occur causing ACTIVATION

A

K4-H3

21
Q

true or false CpG sites exhibit a low frequency of mutation and are upheld in cancer?

A

false, they are highly mutational and have a loss of regulation in cancer

22
Q

if the DNA methylation age is greater than the chronological age, what happens to life expectancy?

A

decreases

23
Q

high CpG island methylation is associated with a …… risk of frailty?

A

increased (by 50%)

24
Q

licking and grooming behaviour of animals is associated with reduced stress in adulthood and increased expression of glucocorticoid receptor in hippocampus. Is it also associated with a loss or an increase of methylation of GR which persists into adulthood? why?

A

loss, because methylation reduces gene expression by repressing txn

25
Q

does methylation reduce or increase txn levels and gene expression levels therefore?

A

reduces txn and gene expression

26
Q

in the dutch hunger winter, lower levels of methylation on which gene occurred?

A

IGF2

27
Q

HATs and HDACs do what to histones?

A

hats add an acetyl, hdacs remove

28
Q

in cancer, mutations of genes controlling the structure of what is associated with epigenetics?

A

chromatin