BIOLOGY 172 Lecture 23: Eukaryotic Gene Regulation (Lectures 23-24)
Document Summary
Eukaryotic genome: very large, multicellularity implies a need for differentiation different cells with different functions. Regulation of gene expression is the mechanisms used during development to accomplish this: the cells in a body each have the entire genome, but regulation makes them different. Pre-transcription chromatin structure: chromatin packing: dna wraps around histones to form nucleosomes. Tight packaging makes it difficult for rna polym to get in. Chromatin must be opened up for a gene to be transcribed. Dna methylation: the enzyme dna methyltransferase (dnmt) adds methyl groups to cytosines, dna methylation is associated with condensed chromatin inhibition of transcription, hemi-methylated dna only one strand is methylated. Modification of histones: usually tails are modified (they stick out of the complex. , example: histone acetylation. Hats add acetyl groups to pos. charged residues. Chromatin remodeling: big complex uses atp to loosen up the chromatin. Transgenerational epigenetic inheritance: inheritance of phenotypic changes not due to dna sequence.
