BIOL 202 Lecture Notes - Lecture 19: Lysine, Ctcf, Enzyme
Document Summary
Molecular mechanisms of imprinting: sex-specific cpg methylation of icr (imprinting control region) only in paternal or maternal gametes. Unmethylated icr binds ctcf and acts as an enhancer-blocking insulator. Icr dna methylation prevents ctcf biding, methylation in promoter can silence transcription. Mutant alleles can act dominantly: if a mutation occurs in an imprinted allele, the outcome is unaffected in the organism, but, if the other sex inherits this gene, it will be affected. Mitochondrial dna in humans is a ~17 nt circular dna molecule. Dozens to hundreds of mitochondria/cell, each w/ multiple mtdna copies. Encodes 2 rrnas, 22 trnas, 13 proteins (all 13 involved in etc: very few non-coding nt"s (no introns or utrs, two promoters transcribed as 2 long rnas )one from each strand), cleaved into individual rnas. Gene sequences are most similar to alpha-proteobacteria (endosymb. Nuclear genes still code for the bulk of mit.
