Epigenetic Phenomena Flashcards
epigenetics
study of stable, heritable changes in gene expression taht do not inolve changes in DNA sequence
regulation of gene expression by epigenetics mechanisms is important for what
- imprinting during development an dgametogensis
- inactivation of X chromosome
- progression of cancer
what do we use as writers of epigenetic information
enzymes that methylate cytosine bases
what do we use as copiers of epigenetic info
enzymes that copy methylation pattern from old DNA over a new strand
what do we use as readers for epigenetic info
enzymes that recognize methylated stretches of DNA and initated sileicning of affected chromsomal regions.
what usually gets silenced by methylation
highly repetitvie DNA
telomeres
centromeres
where are clusters of CpG dinucleotide repeats found
CpG islands close to 5’ region of genes
what happens if CpG islands get methylation
shuts down expression of neighboring genes
what happens if you ahve hypomethylation of genome
expression of genes in normally silent regions of genome
hypomethylation can also reactivate waht
transposable elements in normally genomic regions
how is the pattern of DNA methylation maintained
mitosis by DNA methyltransferase DNMT1
what does DNA polymerase do during DNA replication in the S phase of cell cycle
synthesizes a non-methylated strand on the methyalted template strand
how is the non-methylated strand methylated
by DNMT1
after DNA has been methylated what happens
repression of transtion by binding MBPs
waht do MBPs interact with
repressors of trasncription
HDACs
HDACs favors what
binding of histoones to DNA, leading to chromatin condensation
what modifications are on histones
acetylation
methylation
phosphoryaltion
ubiquination
what happens when you have acetylation of histones
decreases their binding affinity to DNA
what happens when you ahve deacetylation of histones
increases binding affinity, silences transcritpion
what do methylated histones bind to
HP1 proteins
chromosome inaction by cytosine methylation is what kind of process
self-propagating
imprinting of genomic regions is important in what 2 biological processes
development
matuation of gametes
what imprinting happens during development
cell-type specific imprint is establism
what imprint happens during maturation of gametes
parent of origin specific imprint is imposed on chromosomes
what happens to the parent of origin specific imprint during gametogenesis
it gets erased and rewritten - so you reprogram your chromosomes to make them look like yours
inacivation of x chromsome proceeds via waht
imprinting
how is X chromosome inactivated
DNA and histones are on it are methylated, shutting down expression
uniparental disomy
individual only has materal or pateranl imprinted homologues of chromsome
example of uniparental disomy
beckwith-wiedemann
what causes BWS
child inherits both homologues of potion of chromosome 11 from dad
symptoms of BWS
kideny, adrenal, liver problems, severe hypoglycemia
what causes prader willi
deletion on paternal chromosome 15
what causes angelman
deletion on maternal chromosome 15
hypermethylation often causes
loss of gene function
hypomethylation often causes waht
genomic instability
what causes SLE
genome o fT cells is hypomethylated, activity of DNMT1 reduced
