BIOL240 Lecture Notes - Lecture 26: Citric Acid Cycle, Acetyl Group, Glycosylation
15 Mar 2019
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Document Summary
Multiple shine dalgarno sequences allow bacterial mrna to be polycistronic. Inducible genes required at particular times: regulation can take place during transcription, translation or post translation (activity of enzymes). But best to regulate at transcription so you don"t have to waste resources on mrna, proteins etc. Transcription regulation: operon transcription unit with a series of structural genes and their transcription regulatory elements. Consists of promoter (where pol binds), operator, activator binding site and genes for transcription: regulatory protein binds to operator. Negative control of transcription (induction or repression: regulatory protein binds to activator binding site. E. coli has both: some operons can have more than one promoter, each with own control system. Negative control: binding at operator site. Induction is derepression of enzyme production in response to a signal. Like lac operon: typically affects catabolic enzymes, enzymes synthesized only when substrate available, no wasted energy.
