Question

What state is the repressor protein in when tryptophan is absent?

Answer 1

So a repressor protein if activated by certain chemicals will stop the synthesis of a certain gene, in this case, if tryptophan is present, it will bind to the repressor gene on the DNA coding for tryptophan so that the body does not make more than it needs, especially if it present. If there is no tryptophan then the repressor protein is not enabled

Answer 2

So as long as tryp is absent, the repressor that binds to the operon is inactive. This allows RNA polymerase to attach to the DNA at the promoter and transcribe the operon’s genes, as it is not blocked by a repressor.