BIOC 2580 Study Guide - Final Guide: Stem-Loop, Dna Supercoil, Deoxyribonuclease I

• School: University of Guelph
• Department: Biochemistry
• Course: BIOC 2580
• Professor: Shannon De Roo

Document Summary

Moves along the dna strand in the 3" to 5" direction producing a 5" to 3" coding strand. Mg2+ in active site for dna phosphate stabilization. Sigma extends to interact with -10 and -35 to recognize promoter consensus sequences here. Binding of rnap holoenzyme to template dna at promoter. Sigma subunit recognizes promoters to identify the transcription start site. Without sigma, core polymerase can transcribe dna into rna, but cannot initiate this transcription. Can be multiple sigma factors, but usually there is one main one. Begins as a closed promoter complex (no unwinding) Once unwinding begins, it is an open promoter complex. Promoter is a 40 bp region on the 5" side of start site. Tataat pribnow box near -10 and ttgaca consensus sequence near -35 region. The more the -35 sequence lines up with the sigma consensus sequence, the higher the transcriptional efficiency. Unwinding at promoter begins and open promoter complex forms.