BIOC 300B Lecture Notes - Lecture 13: Lac Operon, Allolactose, Lysogenic Cycle
13 Feb 2018
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Document Summary
As lactose is added, betagal production increases proportionally to total bacterial proportion. Upon removal of lactose, the betagal production plateaus which represents stability of betagal (has a relatively long half-life) glucose present with lactose. Minimal transcription because allolactose must be produced under all conditions (incase of glucose starvation) Maximal transcription of the lac operon requires an. In the presence of lactose only (glucose starvation) cap/crp binds camp causing a conformational shift in protein so that it can bind the dna nucleotide sequence that is upstream/adjacent to the promoter. Conformational shift is encouraged by protein:protein interactions formed by cap residues that stabilize the formation of a closed complex camp is a positive effector ligand for cap: Camp activates dna binding and up regulates transcription. Bases of ligand = no binding of dna. Binds dna sequence right beside the promoter. Recognition of the alpha helix occurs @ top > decodes the base pairs present and forms protein:dna interactions.
