L17 Epigenetic

Question 1

define phenotypic plasticity

Answer 1

Variation, under environmental influence, in the phenotype associated with a genotype
i.e. same cell in dif enviro=diff expression

Question 2

difference b/w genetic changes and epigenetic changes

Answer 2

genetics= mutations changing DNA sequence

epi= alterations to change packaging

Question 3

define epigenetics

Answer 3

modifications resulting in altered regulation of gene expression without involving changes in the DNA sequence (inherited; chromatin modification) + heritable (genetically identical cells= express different genomes // phenotypes)

Question 4

what influences the epigenome

Answer 4

enviro +genetics

Question 5

what is a nucleosome

Answer 5

dna wrapped around 8 histone octamers

Question 6

what part of the histone has chemical modification

Answer 6

histone tails (myth/acety)

Question 7

what does acetylation do

Answer 7

open structure

Question 8

what does mythelation do to histone structure

Answer 8

closed

Question 9

why is an open structure allow active transcription

Answer 9

active transcription more likely (proteins can easily attach + high accessibility)

Question 10

what occurs if CpG island heavily methylated

Answer 10

Silenced 
not accessible (transcription factors cannot attach)

Question 11

what is a CpG island

Answer 11

C Has additional methyl group = on many= clustered = CPG island

Question 12

what occurs if a silencer is methylated

Answer 12

turned off and // allows trancription

Question 13

what occurs if a silencer is unmethylated

Answer 13

turned on + functioning and silencing whole process= not transcribed

Question 14

why would a certain area not be expressed on a histone

Answer 14

1. Closed/repressed structure (methy tails on histones)

2. CpG islands (clusters of CG)= methylated // supresses

Question 15

when does demethylation occur in development and why

Answer 15

• Often demethylation after fertilization= typically turned on for short period
o Pluripotent turned on

Question 16

why does concordance decrease with age

Answer 16

o Often due to different environmental insults

Question 17

link between epigeneim profile in early age of twins vs older

Answer 17

• Epigenetic profile of early twins= similar

* Older= expression level much different

Question 18

how can genetic variation influence epigenetic profile

Answer 18

• example change in single nucleotide= influence methylation profile (if C changed to another nucleotide), whether proteins can attach

Question 19

epigenetic controls of cancer

Answer 19

• Gene controls cell proliferation
o Nromal cell= open state, and CPG island in open state and unmetyhlated allowing transcirption

• If now has methyl tags= cannot be transcribed + CpG island methylated
o Enviro stimuli may have activated process of changing tags

Question 20

how does microbiome influence epigeneics

Answer 20

Microbiome: produces metabolites which affect epigenetic profile which influences phenotype in tolerance to bacteria