Biochemistry 2288A Lecture Notes - Lecture 15: Adenine, Spliceosome, Polyadenylation
23 Jan 2017
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Document Summary
The 5 genes req"r for tryptophan biosynthesis are transcribed from a common promotor trp repressor binds tryptophan when there is lots of tryptophan in the cell: has 107 residues. Trp repressor- tryptophan complex binds the operator: blocks rna polymerase from the promotor, polymerase can"t park the promotor. Tryptophan causes a conformational (shape) change in the trp repressor that allows it to bind. General themes to take from the trp operon: trp repressor is a site specific dna binding protein. There is a binding site for trp repressor with the trp promotor trp repressor inhibits transcription by blocking rna polymerase from the promotor trp repressor is responsive to an environmental signal. Lac operon- expression is required for the metabolism of lactose. Positive control catabolite activator protein: transcriptional activator. Lac repressor binds dna in the presence of lactose. Lactose -lac repressor does not bind dna.
