Epigenetics Flashcards
Epigenetics
Study of heritable changes that do not change DNA sequence
Epigenetic inheritance
Replication of methylated site->hemimethylated DNA so only parental strand methylated->constitutive DNA methyltransferases restore methylation of hemimethylated DNA
Perpetuation of epigenetic effects through:
Protein structure assembled on DNA, covalent mod of DNA, protein aggregates that control conformation of new subunits
Prion formation
Spontaneous generation of PrPc (normal glycoprotein), conversion of it to PrPSC (conformationally altered isoform), accumulation of PrPSC (toxicity)
Prion inheritance and phenotypes come about through _________
Protein folding
Heterchromatin extension ________ genes
Inactivates
Epigenetic drift
Decrease in genome methylation within replications
DNA methylation occurs at ________
CpG islands along DNA, on cytosines
Methylation associated with ________ in eukaryotes
Transcription control, methylation=gene inactivation
Telomeric silencing in yeast
Translocation of genes to telomeric region -> inactivation
Histone methylation associated with heterochromatin formation
Genes in heterochromatin regions inactivated
HP1
Key protein for mammalian heterochromatin, acts by binding to methylated histone H3
SIR genes
Silent information regulators, drive heterochromatin formation in telomeres and silencing MAT locus in yeast
Polycomb (Pc-G) and Trithorax (TrXG) group proteins
PcG maintain chromatin repression genes in a repressed state, TrXH antagonizes them. TrXH makes chromatin continuously accessible to TF
DNA satellites
Very large arrays of tandemly non-coding, repeating DNA
Methylation functional targets
1) Gene promoters (demethylation at promoters) 2) DNA satellites (centromere instability)
DNA hypermethylation early event of ________
Tumorigenesis
Tumor suppressor genes silenced in breast cancer
PTEN, APC, SFN
Dosage compensation
Organisms equalizing expression of X-linked genes between members of different sexes
Constitutive heterochromatin
Contain specific sequences without coding function
Facultative heterochromatin
DNA regions inactive in one cell lineage but expressed in other cell lineages
Single X hypothesis
Inactivation of one X chromosome in female mammals
Chromosome condensation caused by ______
Condensins
SMC (structural maintenance of chromosome) protein are ATPases (2):
Condensins: condensation into compact chromosomes during mitosis, cohesins: connect sister chromatids
Genetic imprinting
Selective expression of gene according to the parental origin of the allele
Imprinting does not follow classic ________
Genetics laws
Imprinting is set in each sex during _________
Gametogenesis
