BIOC 2580 Study Guide - Final Guide: Glycerol, Transfer Rna, Lac Operon
16 Dec 2015
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E. coli prefers to use tryptophan from its environment rather than make its own since making its own costs a lot of energy. Trp operon synthesizes tryptophan when the level of tryptophan is low in the cells. Followed by trpl which encodes a leader sequence and an attenuator region. Trp repressor binds to operator when there are high levels of tryptophan reducing transcriptional rate 70-fold (negative. Like lac operon, the trp repressor does not allow rnap to bind the promoter the trp repressor also regulates the trpr operon and is itself encoded by the trpr operon (autoregulation) Trp repressor on its own cannot be the only thing controlling tryptophan synthesis. It acts to inhibit the rnap after it has already bound and started. It acts to inhibit the rnap after it has already bound and started transcribing. Can only work in bacteria because transcription and translation happen at the same time (cannot happen in eukaryotes)
