Biochemistry 2280A Lecture 23: Topic 23 - Transcription.docx
18 Mar 2014
School
Department
Course
Professor
Document Summary
Transcription - significance: because transcription is first step, it"s often regulated, many diseases result from defects in transcription factors (cancer, the specificity of many transcription factors make them logical drug targets. Prokaryotic transcription: mechanistically similar to euk transcription. Terminology: promoter: dna sequences required to initiate transcription of gene (or operon) Recognize any gene specific regulatory factors (transcription factors) Promoter is not transcribed, but it"s required for transcription. Asymmetrical binds to polymerase in only one orientation. A set of genes clumped together (usually functionally related) Proks: polysystronic (multiple protein products made from one gene sequence) Euks are monosystronic: terminator: dna sequence required to terminate/stop transcription. November 8, 2012: start site = +1, sequence after (downstream) that is +2, sequence before(downstream) is -1; there is no 0. 10 sequence and -35 sequence (10 and 35 back from +1: how they were discovered. Aligned sequences from a group of e. coli promoters (+1) Upstream from +1 (-10) had conserved sequences (pribnow box)
