BIO 2306 Lecture Notes - Lecture 17: Cytosine, Deoxyribonuclease I, Histone Deacetylase
Document Summary
Chapter 17: control of gene expression in eukaryotes. Regulation at multiple levels: changes in chromatin structure. When dna is tightly packaged, transcription is inhibited (can"t nd promoter) Dnase i hypersensitive sites: regions of the dna that is not highly packaged, thus are sensitive to digestion by dnase i: chromatin remodeling. Proteins bind to dna and reposition the nucleosomes. Allows transcription factors to bind to promoters: histone modi cation, methylation of histones. Can package the dna more or less depending on which animo acid of the histone are methylated. Demethylase remove methyl groups: acetylation of histones. Causes positive charge histone to be neutralized. Negatively charged dna no longer has an af nity for the histones. Deacetylase remove acetyl groups: dna methylation. Methyl groups added to cytosine in dna. Attracts deacetylases, which remove acetyl groups from histone. Cpg islands: stretched of dna high in guanine and cytosine nucleotides.
