L17 Epigenetic Flashcards
define phenotypic plasticity
Variation, under environmental influence, in the phenotype associated with a genotype
i.e. same cell in dif enviro=diff expression
difference b/w genetic changes and epigenetic changes
genetics= mutations changing DNA sequence
epi= alterations to change packaging
define epigenetics
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)
what influences the epigenome
enviro +genetics
what is a nucleosome
dna wrapped around 8 histone octamers
what part of the histone has chemical modification
histone tails (myth/acety)
what does acetylation do
open structure
what does mythelation do to histone structure
closed
why is an open structure allow active transcription
active transcription more likely (proteins can easily attach + high accessibility)
what occurs if CpG island heavily methylated
Silenced not accessible (transcription factors cannot attach)
what is a CpG island
C Has additional methyl group = on many= clustered = CPG island
what occurs if a silencer is methylated
turned off and // allows trancription
what occurs if a silencer is unmethylated
turned on + functioning and silencing whole process= not transcribed
why would a certain area not be expressed on a histone
- Closed/repressed structure (methy tails on histones)
2. CpG islands (clusters of CG)= methylated // supresses
when does demethylation occur in development and why
• Often demethylation after fertilization= typically turned on for short period
o Pluripotent turned on
why does concordance decrease with age
o Often due to different environmental insults
link between epigeneim profile in early age of twins vs older
- Epigenetic profile of early twins= similar
* Older= expression level much different
how can genetic variation influence epigenetic profile
- example change in single nucleotide= influence methylation profile (if C changed to another nucleotide), whether proteins can attach
epigenetic controls of cancer
• 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
how does microbiome influence epigeneics
Microbiome: produces metabolites which affect epigenetic profile which influences phenotype in tolerance to bacteria
