BIOLOGY 1A03 Lecture Notes - Lecture 11: Guanine, Nucleosome, Eukaryotic Transcription

• School: McMaster University
• Department: Biology
• Course: BIOLOGY 1A03
• Professor: Rosada Silva

Document Summary

Transcription factors: proteins that bind to specific sequences in dna. In eukaryotes each gene is controlled by its own promoters and enhancers. Dna is organized into highly compacted chromatin. Tightly wound because of (+) charged tails of histone proteins with (-) charged phosphates in dna: to transcribe, it is necessary to unwind the dna. Other chemical modifications: methylation (ariginine and lysine), phosphorylation (threonine and serine) Alter the charges of these tails alter binding to the dna. Cis-sequences (promoter sites) required to initiate transcription: tata box + transcriptional sites form part of core promoter, tata box region recognized by tata-binding protein (tbp, bre region recognized and bound by tfiib general transcription factor. Enhancer regions (in regulatory promoter regions): can bind cell/region specific transcription factors: transcription factors then interact with basal machinery to enhance transcription. Eukaryotic transcription facilitated by adaptor/mediator proteins connecting enhancer and core promoter regions.