試題詳解

22. In E. coli, biosynthesis of tryptophan can be repressed. The repressor protein of the trp operon
(A) is activated by the binding of tryptophan.
(B) is inactivated by the binding of tryptophan.
(C) is not affected by tryptophan.
(D) is activated by the binding of free tRNA.
(E) is only synthesized in the presence of tryptophan.