W12 Epigenetics

Question 1

What is epigenetics

Answer 1

study of heritable changes that affect gene activity and expression
no changes to DNA sequence

Question 2

what is epigenetics used for

Answer 2

gene expression
determines cell specialization

Question 3

Is epigenetic modification reversible

Answer 3

yes

Question 4

What are the 3 main mechanisms of epigenetics

Answer 4

DNA modifications
post-translation histone modifications
histone variants

Question 5

What is a nucleosome

Answer 5

chromatin made of 147 base pairs of DNA wrapped around a histone octamer core

Question 6

What proteins make up the histone octamer

Answer 6

2 H2A-H2B dimers
1 H3-H4 tetramer

Question 7

What is the function of histone tail modifications

Answer 7

regulate gene expression by creating or stopping the binding of regulatory proteins

Question 8

What is the histone code

Answer 8

code on histone tails that regulate chromatin structure

Question 9

what is the histone modification for gene activation

Answer 9

acetylation

Question 10

what is the histone modification for gene repression

Answer 10

trimethylation

Question 11

how does acetylation increase gene expression

Answer 11

removes positive lysine so the DNA becomes more negative
easier for transcription factors and RNA polymerase to bind

Question 12

What is DNA methylation

Answer 12

addition of a methyl group to the 5th carbon of cytosine
represses gene activation

Question 13

What enzymes catalyse DNA methylation

Answer 13

DNMT1/3

Question 14

What happens to gene expression when CpG islands are methylated

Answer 14

reduced gene expression

Question 15

Where are CpG islands typically found

Answer 15

at promoters

Question 16

What role does DNA methylation play in cancer

Answer 16

less expression of TSG

Question 17

What is genomic imprinting

Answer 17

gene expression is determined by the parent of origin regulated by DNA methylation

Question 18

Give an example of an imprinting disorder

Answer 18

Prader-Willi Syndrome

Question 19

What is Prader-Willi Syndrome caused by

Answer 19

no active paternal genes in chromosome 15

Question 20

What is X-inactivation

Answer 20

where one X chromosome is epigenetically silenced

Question 21

How can the environment affect the epigenome

Answer 21

can lead to mutations in DNA

Question 22

What are polyphenisms

Answer 22

two or more phenotypes from a genotype due to environmental factors

Question 23

How does royal jelly influence honeybee development

Answer 23

inhibits DNMT3
less DNA methylation so genes to remain active

Question 24

What is the epigenetic difference between queen bees and worker bees

Answer 24

Queen bees have lower DNMT3 activity

Question 25

What 3 epigenetic changes due to air pollution

Answer 25

DNA methylation histone modifications miRNA expression

Question 26

What happens to DNA methylation after fertilization

Answer 26

demethylation of genome then re-methylation during development

Question 27

Why is DNA methylation important for development

Answer 27

supresses unwanted genes

Question 28

What is the role of CpG islands in development

Answer 28

remain unmethylated to regulate gene activation

Question 29

What are CpG sites

Answer 29

C then G next to each other in the DNA seq

Question 30

What is a histone deacetylase inhibitor for

Answer 30

prevents the removal of acetyl groups reactivates silenced genes

Question 31

What is the are miRNAs in epigenetics for

Answer 31

regulate gene expression post-transcription

Question 32

What is an activating histone modification

Answer 32

Acetylation on lysine of histone tails

Question 33

What is a repressive histone modification

Answer 33

Methylation of H3K9 or H3K27

Question 34

What is the primary function of DNMT3

Answer 34

make new DNA methylation patterns