GCD 3022 Lecture Notes - Lecture 11: Lac Repressor, Lac Operon, Repressor
9 Mar 2018
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Document Summary
Gene regulation is the phenomenon in which the level of gene expression can vary under different conditions. By comparison, constitutive genes are expressed at relatively constant levels. Gene regulation can occur at transcription, at translation or posttranslation. Repressors and activators are proteins that exert negative control or positive control, respectively. Small effector molecules control the function of repressors and activators. Enzyme adaptation is the phenomenon in which the enzymes that metabolize a molecule are made only when the molecule is present in the environment. The lac operon encodes a polycistronic mrna for proteins that are involved with the uptake and metabolism of lactose. The lac repressor binds to the lac operator and inhibits transcription. Allolactose binds to the repressor from binding to the operator. The regulation of the lac operon enables the bacterium e. coli to respond to changes in the level of lactose in its environment.
