BIO 230 Lecture Notes - Lecture 11: Small Interfering Rna, Ribosome, Protein Folding
19 Apr 2018
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Ch 11: regulation of gene expression in bacteria and their viruses. Biochemical assay to measure mrna, protein or both. Reliable conditions which expression levels differ in wt genotypes. Jacob and monod got evidence for operator and repressor. They used a synthetic inducer bc allolactose is hydrolysed by beta- gallatosidase and iptg isnt. Found lots of mutations that altered gene expression but to study the interactions they needed diploids :/ In presence of super repressor- lac operon is always repressed. Is super-repressor mutation, prevents expression when the inducer is present. Molecular characterization of the lac repressor and the lac operator. Lac operon is transcribed only in the presence of lactose! Two environmental conditions have to be satisfied for lactose metabolites to be expressed. The cell can capture more energy from the breakdown of glucose than other sugars. Lactose breaks down into glucose and galactose, so the presence of glucose stops lac operon expression. Catabolite repression of the lac operon: positive control.
