BIO_SC 2200 Lecture Notes - Lecture 35: Euchromatin, Heterochromatin, Deprogramming
Document Summary
Pluripotent cells able to form any lineage (cell type/developmental fate): Accompanied by progressive lineage specific constraint on local specific chromatin loop structure. Consequently the range of enhancer-promoter contacts that are permitted is progressively limited. Specific regions of the genome are permanently turned off ex. Methylation of dna at clusters or islands of cytosine (cpg islands) Methylation begins very early in development and the extent of methylation increasing during development as the fate of individual cells becomes progressively more restricted [by that methylation] *there was a massive de-methylation (deprogramming) in primordial germ cells. Dna methylation provides a genetic memory- the pattern is inherited. The methylation pattern is replicated every time the genome is replicated- each old methylated strand serves as a template for the methylation of the newly synthesized strand at the same sites. Because the genome is modified, but the dna nucleotide sequence is not, these changes are called epigenetic.
