The tryptophan operator . a. is an allosteric protein. b. binds to the tryptophan repressor when the repressor is bound to tryptophan. c. is required for production of the mrna encoded by the tryptophan operon. d. is important for the production of the tryptophan repressor.

B. binds to the tryptophan repressor when the repressor is bound to tryptophan.

Explanation:

Bacterial genes are commonly composed of operons that are activated or deactivated depends on the needed. If the bacteria need, for example, an amino acid such as tryptophan for synthesizing proteins. An activator "turns on" the transcription that the operon has and produces the amino acid.

On the other hand, if the bacteria have a high presence of tryptophan amino acid, a repressor binds to the tryptophan operator and avoids the amino acid transcription, in consequence, constrain the tryptophan production.

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.