Epigenetics, Genomic Imprinting, and X-inactivation

Question 1

Epigenetics

Answer 1

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

Question 2

Epigenetic change brings

Answer 2

Altered expression levels

Question 3

Mutated gene brings

Answer 3

Altered protein structure or altered protein level

Question 4

Skewered X-inactivation

Answer 4

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

Question 5

Xist location

Answer 5

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

Question 6

Xist encodes

Answer 6

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

Question 7

Xist lncRNA

Answer 7

Coats the inactive X chromosome and facilitates its silencing

Question 8

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

Answer 8

5mC…followed by a G…CpG dinucleotide

Question 9

Other thing that happens to 5mC

Answer 9

Hydroxylated to become 5hmC

Question 10

Enzymes responsible for methylating cytosine

Answer 10

DNMT…needs SAM-CH3…releases SAM

Question 11

DNMT1

Answer 11

Maintenance methylase

Question 12

DNMT3a and DMNT3b

Answer 12

De novo methylases

Question 13

Methylation pattern is maintained through

Answer 13

Cell division

Question 14

CpG dinucleotides found more often in

Answer 14

Promoters (CpG islands)

Question 15

Most CpGs are

Answer 15

Methylated…EXCEPT for CpG islands which are typically unmethylated

Question 16

Increase/decrease methylation effects

Answer 16

Increase - transcriptional silencing

Decreased - increased transcription

Question 17

Chromatin composition

Answer 17

DNA , RNA, and porteins

Question 18

Chromatin function and what is unique quality

Answer 18

Packages DNA but allows for replication, repair, and trascription

It is dynamic

Question 19

Nucleosome made of

Answer 19

DNA and histone

Question 20

Nuclease will

Answer 20

Digest linker DNA

Question 21

High concentration of salt will

Answer 21

Dissociated histone core and DNA

Question 22

Component parts of nucleosome

Answer 22

H2A, H2B, H3, H4

Question 23

Histone variation

Answer 23

Variant forms can be incorporated into nucleosome

Question 24

Histone mobilization

Answer 24

Enzymes can more nucleosomes

Question 25

Histone modification

Answer 25

Multiple types exist

Question 26

Histones are moved by

Answer 26

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

Question 27

Nucleosome free regions are

Answer 27

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

Question 28

Acetylation and deacetylation of histones

Answer 28

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

Question 29

Histone code is

Answer 29

Dynamic and has memory

Question 30

Genomic imprinting

Answer 30

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

Question 31

Paternal and maternal autosomal genes are

Answer 31

Both required for normal development...NOT equally expressed

Question 32

Many imprinted genes control

Answer 32

Embryonic growth and brain fevelopment

Question 33

H19 codes and regulation

Answer 33

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

Question 34

Igf2 encodes and regulation

Answer 34

Fetal growth factor...only male derived...maternal is imprinted

Question 35

Mechanism of H19 and IGF2

Answer 35

Maternal - CTCF bound to insulator so H19 is on Paternal - insulator and H19 heavily methylated so IGF2 is on Enhancer helps transcirbe both

Question 36

Transcriptionally active DNA charactersitics

Answer 36

Open chromatin Hypomethylated DNA Histones acetylated Transcriptionally asilent is the opposite

Question 37

Barker Hypothesis

Answer 37

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

Question 38

Oncogenes activated by

Answer 38

Loss of DNA methylation

Question 39

TUmor suppressors silenced by

Answer 39

DNA methylation

Question 40

Mutation of imprinted genes can lead to

Answer 40

Prader-willi and Angelman's syndrome

Question 41

When are x-chromosomes inactivated in females?

Answer 41

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

Question 42

Xist located in

Answer 42

X-inactivation center

Question 43

Sole methyl donor for DNA methylation

Answer 43

S-adenyl methionine (SAM)

Question 44

How is methylation passed during replication?

Answer 44

During DNA replication, will have a hemimethylated strand until maintenance methylase comes in an methylates so that pattern is maintained (DNMT1)