Lecture 10 - Epigenetics

Question 1

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

Answer 1

heritable
not
DNA

Question 2

how can epigenetics be modified, 2 ways?

Answer 2

environmentally and pharmacologically

Question 3

name 3 markers of epigenetics

Answer 3

DNA methylation, histone modifications and miRNA

Question 4

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

Answer 4

position 5

Question 5

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

Answer 5

DNMT1, 3a, 3b

Question 6

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

Answer 6

5-methylcytosine

Question 7

at which dinucleotides does DNA methylation only ever occur at?

Answer 7

CpG

Question 8

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

Answer 8

false, it is

Question 9

what percentage of CpGs are methylated?

Answer 9

70%

Question 10

true or false, the genome is CpG poor?

Answer 10

true

Question 11

which version of cytosine is prone to mutation?

Answer 11

J-cytosine

Question 12

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

Answer 12

MBD3, MBD2

Question 13

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

Answer 13

brain, ES cells

Question 14

is hydroxy methylation copied by DNMT1?

Answer 14

no

Question 15

name the 4 possible histone modifications

Answer 15

acetylation, methylation, phosphorylation, ubiquitination

Question 16

in histone modification, acetylation can do which 3 things?

Answer 16

activation, decompaction of chromatin, permissive

Question 17

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

Answer 17

non-permissive

Question 18

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

Answer 18

inactivation, compaction, non-permissive

Question 19

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

Answer 19

K9-H3
K27-H3

Question 20

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

Answer 20

K4-H3

Question 21

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

Answer 21

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

Question 22

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

Answer 22

decreases

Question 23

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

Answer 23

increased (by 50%)

Question 24

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?

Answer 24

loss, because methylation reduces gene expression by repressing txn

Question 25

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

Answer 25

reduces txn and gene expression

Question 26

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

Answer 26

IGF2

Question 27

HATs and HDACs do what to histones?

Answer 27

hats add an acetyl, hdacs remove

Question 28

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

Answer 28

chromatin