試題詳解

38. Which of the following is/are TRUE about operons?
(A) A single operon usually contains all the enzymes which are specific for the synthesis of a special biomolecule.
(B) The effector for the Lac repressor protein is β-galactosidase.
(C) Cyclic AMP affects transcription by phosphorylating a transcription factor.
(D) Regarding regulation of the trp operon, the amino acid tryptophan acts as a corepressor.
(E) Regarding the lactose utilization system in E. coli, a constitutive mutant is one in which the three enzymes are produced regardless of the presence or absence of lactose.