Epigenetics Flashcards
Susceptibility to health and disease is somehow encoded…
in the genetic material
Epigenetic information determines…
how, when and where the sequence data is used
Individual chromosomes occupy…
distinct territories
Compartments, corresponding to______________________, _________________ the genome.
open and closed chromatin, spatially partition
Epigenetics, in molecular terms, represents…
range of chromatin modifications, inc.:
- DNA methylation
- histone modifications
Methylation
not evenly spread (CPG (lots of Cs and Gs) islands)
often found in promotion sequences
denoval methylation
no methylation before
3A/3B/3L
methyltransferases
TET - take off methyl groups
maintenance methylation
already have methyl group
DNMT1
produce 2 copies of DNA with methylation
methyl groups - fall off during methylation or TET
open chromatin =
active => available for transcription
closed chromatin =
condensed
open chromatin -> closed chromatin
histone methylation and deacetylation
closed chromatin -> open chromatin
histone demethylation and acetylation
methylation at promoters =>
gene expression repression
methyl - from metabolism
phenolmethionine cycle
acetyl - from metabolism
general
bisulphite sequencing
if not protected by methyl group C -> U -> T +bisulphite
Immunoprecipitation
break DNA into fragments
antibody specific to CPGs -> chip -> enriched
Epigenetic clock concept
variation increases with age
global methylation falls with age
(gene specific increas or decrease though)
Epigenetics allows the environment to…
modify the genome
Transposable elements, aka?
‘jumping genes’
Retrotransposons duplicate through…
RNA intermediates that are reverse transcribed and inserted at new genomic locations.
The ongoing expansion of non‐LTR retrotransposons has created…
significant inter‐individual variation in retrotransposon content
Regulating transposable elements
Methylation has the effect of repressing transposition and protecting the early embryo in particular from potentially damaging genome rearrangement during critical periods of development
Heavily methylated = don’t transpose
Imprinted genes
Imprinted – remember which parent they came from
