The trp operon contains five genes trpE, trpD, trpC, trpB, and trpA. These five
ID: 10522 • Letter: T
Question
The trp operon contains five genes trpE, trpD, trpC, trpB, and trpA. These five genes code for components that produce three enzymes that catalyze the biosynthesis of tryptophan. The trpL region is the leader region, which helps regulate transcription once RNA polymerase has initiated transcription. The trp operon also undergoes negative regulation by a repressor. Tryptophan is the signal molecule (effector molecule) that binds to the repressor. Determine which events lead to an increase in transcription. The trp operon is transcribed when the trp repressor dissociates from DNA. the trp repressor is inactive. Trp is present at high concentrations inside the cell. the trp repressor is bound to the operator. trp binds to the repressor.Explanation / Answer
Ans:- The trp operon is transcribed when the trp repressor dissociates from DNA.
Events for increase in transcription:-
1) trpR gene produces repressor.
2) In presence of tryptophan, trp repressor binds with tryptophan, causing a conformational change that permits the repressor to bind to the trp operator and inhibit expression of the trp operon.
3) Once repression is lifted and transription begins.
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