BIOL 1115 Lecture 13: Chapter 13
9 Mar 2017
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Document Summary
Chapter 13: overview of gene regulation, gene regulation, gene expression, types of genes, unregulated: constitutive genes, regulated, prokaryotic gene regulation, response to, ex: escherichia coli and lactose. Lac operon: e. coli, contains genes for lactose metabolism, three structural genes. Laz- -galactosidase lacy- lactose permease laca-galactosidase transacetylase lacp- lac promoter: regulatory sites near the lac promoter. Laco operator: cap site- activator protein binding site. Lac operon without lactose: when lactose is absent. Lac repressor protein: exerts negative control binds to nucleotides of the lac operator site, prevents rna polymerase from transcribing lacz, lacy, and laca, note: rna polymerase binds but does not transcribe. Lactose is low and glucose is high or low: when lactose is low and glucose is high or low, the lac operon is shut off, under low lactose conditions, lac repressor prevents transcription of lac operon. Lac and trp repressors: lac repressors binds to its operator in the absence of its small effector molecule.
