Epigenetic Phenomena

Question 1

epigenetics

Answer 1

study of stable, heritable changes in gene expression taht do not inolve changes in DNA sequence

Question 2

regulation of gene expression by epigenetics mechanisms is important for what

Answer 2

• imprinting during development an dgametogensis
• inactivation of X chromosome
• progression of cancer

Question 3

what do we use as writers of epigenetic information

Answer 3

enzymes that methylate cytosine bases

Question 4

what do we use as copiers of epigenetic info

Answer 4

enzymes that copy methylation pattern from old DNA over a new strand

Question 5

what do we use as readers for epigenetic info

Answer 5

enzymes that recognize methylated stretches of DNA and initated sileicning of affected chromsomal regions.

Question 6

what usually gets silenced by methylation

Answer 6

highly repetitvie DNA
telomeres
centromeres

Question 7

where are clusters of CpG dinucleotide repeats found

Answer 7

CpG islands close to 5’ region of genes

Question 8

what happens if CpG islands get methylation

Answer 8

shuts down expression of neighboring genes

Question 9

what happens if you ahve hypomethylation of genome

Answer 9

expression of genes in normally silent regions of genome

Question 10

hypomethylation can also reactivate waht

Answer 10

transposable elements in normally genomic regions

Question 11

how is the pattern of DNA methylation maintained

Answer 11

mitosis by DNA methyltransferase DNMT1

Question 12

what does DNA polymerase do during DNA replication in the S phase of cell cycle

Answer 12

synthesizes a non-methylated strand on the methyalted template strand

Question 13

how is the non-methylated strand methylated

Answer 13

by DNMT1

Question 14

after DNA has been methylated what happens

Answer 14

repression of transtion by binding MBPs

Question 15

waht do MBPs interact with

Answer 15

repressors of trasncription

HDACs

Question 16

HDACs favors what

Answer 16

binding of histoones to DNA, leading to chromatin condensation

Question 17

what modifications are on histones

Answer 17

acetylation
methylation
phosphoryaltion
ubiquination

Question 18

what happens when you have acetylation of histones

Answer 18

decreases their binding affinity to DNA

Question 19

what happens when you ahve deacetylation of histones

Answer 19

increases binding affinity, silences transcritpion

Question 20

what do methylated histones bind to

Answer 20

HP1 proteins

Question 21

chromosome inaction by cytosine methylation is what kind of process

Answer 21

self-propagating

Question 22

imprinting of genomic regions is important in what 2 biological processes

Answer 22

development

matuation of gametes

Question 23

what imprinting happens during development

Answer 23

cell-type specific imprint is establism

Question 24

what imprint happens during maturation of gametes

Answer 24

parent of origin specific imprint is imposed on chromosomes

Question 25

what happens to the parent of origin specific imprint during gametogenesis

Answer 25

it gets erased and rewritten - so you reprogram your chromosomes to make them look like yours

Question 26

inacivation of x chromsome proceeds via waht

Answer 26

imprinting

Question 27

how is X chromosome inactivated

Answer 27

DNA and histones are on it are methylated, shutting down expression

Question 28

uniparental disomy

Answer 28

individual only has materal or pateranl imprinted homologues of chromsome

Question 29

example of uniparental disomy

Answer 29

beckwith-wiedemann

Question 30

what causes BWS

Answer 30

child inherits both homologues of potion of chromosome 11 from dad

Question 31

symptoms of BWS

Answer 31

kideny, adrenal, liver problems, severe hypoglycemia

Question 32

what causes prader willi

Answer 32

deletion on paternal chromosome 15

Question 33

what causes angelman

Answer 33

deletion on maternal chromosome 15

Question 34

hypermethylation often causes

Answer 34

loss of gene function

Question 35

hypomethylation often causes waht

Answer 35

genomic instability

Question 36

what causes SLE

Answer 36

genome o fT cells is hypomethylated, activity of DNMT1 reduced