LIFESCI 2G03 Lecture Notes - Lecture 16: Methylation, Meiosis, Chromosome
Document Summary
Activator cannot interact with core promoter of igf2 = expression is off on maternal chromosome. This is because of ctcf, the repressor protein. Because of cpg island methylation, activator cannot bind, h19 gene silenced. *overall: igf2 is on, h19 is off, they cannot be on at the same time normally. Epigenetic effect whatever silences the maternal or paternal gene is not encoded in the dna. The factor is outside the gene, but is heritable. Methylation can be maintained across generations by methylase that recognize methyl groups on one strand and respond by methylating the opposite strand. Maternal homologue = un-methylated, paternal homologue = methylated. Methylated state is also replicated after dna replication has occurred. See addition of more methyl groups onto only the chromosome that already had methyl groups. End up with 2 cells that are epigenetic copies of each other (epigenetic state is replicated/ stable through mitotic division)