Biochemistry 2280A Lecture Notes - Lecture 2: Operon, Enzyme, Recognition Sequence
21 Nov 2017
School
Department
Course
Professor
Document Summary
How are different bacterial promoters transcribed at different levels: some genes have better -10 and -35 sequences. 10 and -35 are key to recruiting rna polymerase. Different levels of expression of the gene. Not dynamic: there"s more than 1 sigma factor - each recognizes different promoter sequences. Most common = (cid:3776) housekeeping sigma , regulates most genes. (cid:3775)(cid:3774) = nitrogen metabolism - induces various other specialty genes required for growth in low nitrogen conditions. = turns on another set of gene in response to heat shock (bacteria only: gene specific regulatory proteins. Regulates induction or repression of certain genes. Negative regulation - trp operon of e. coli (fig. The trp operon has 5 genes required for tryptophan biosynthesis are transcribed from a common promoter. In-class question: when is the trp operon expressed: when there is a lot of tryptophan in the cellular environment, when there is little tryptophan in the cellular environment, when glucose is low, all the time.
