Question

1. Describe the regulation of the trp operon (a) in the presence of tryptophan and (b) the absence of tryptophan. Name all components involved and tell where they bind.

Answer 1

You're better off asking this in Biology...I'm a bio/math lover so here:
a)When tryptophan is present, the repressive protein blocks the operator, and tryptophan repressor tetramers bind to tryptophan, which makes a change in conformation in the repressor. This allows the repressor to bind the operator and then prevents RNA polymerase from binding to and transcribing the operon.

b) When tryptophan is not present, the repressor is in inactive conformation and can't bind the operator region. So the repressor doesn't inhibit transcription.