When the cellular level of tryptophan decreases in E. coli:
A) tryptophan-bound Trp repressor associates with trp operator.
B) Trp aporepressor has lowered affinity for trp promoter allowing RNA. polymerase binding and transcription of the trp operon.
C) tryptophan binds trp inducer to promote positive control of trp promoter.
D) trp repressor has a greater affinity for trp operator.
E) none of the above.

Question

Quizplus · Accepted Answer

When the cellular level of tryptophan decreases in E. coli, the Trp aporepressor, which requires tryptophan to bind effectively to the trp operator and repress transcription, has a lowered affinity for the trp operator. This allows RNA polymerase to bind to the trp promoter and initiate transcription of the trp operon, leading to the synthesis of enzymes involved in tryptophan synthesis.

When the Cellular Level of Tryptophan Decreases in E