Biochemistry 2288A Lecture Notes - Lecture 3: Catabolite Repression, Lac Operon, Lac Repressor

• School: Western University
• Department: Biochemistry
• Course: Biochemistry 2288A
• Professor: Susan Meakin

Document Summary

Lecture 3 monday transcription cont (the first step in gene regulation) Neg control: lac repressor (works similar to trp repressor) Pos control: catabolite activator pro (induced gene expression by recruiting rna polymerase) Six differences in transcription bw prok & eukaryotes: 3 rna polymerases in eukaryotes. Pol i: most rrna genes pol ii: mrnas. Pol3: trna, 5s, rrna (vs bacteria only have 1, euk have 3. : no operons in eukaryotes. Each gene is transcribed as a single unit. Promoter do not have -10 & -35 sequences there is no sigma factor. Promoter recognition is determined by a set of pro, one of which ecognizes a tata- element. Dna looping: combinational control: groups of pro work together to determine the expression of a gene. In euk there can be many regulatory pro binding. In bacteria, the promoter is either on or off vs eukaryotic can be on, off, or anywhere in bw.