Question

A certain strain of E. coli is constitutive for the enzymes for lactose metabolism. On an F' plasmid you have the choice of adding one (but only one) element of the lac system to make the bacteria a merodiploid for that element. Assume the original E. coli has wild-type structural loci. If your goal is to determine whether the lac operon is constitutive because of a mutant regulator OR because of a mutant operator, which one wild-type element of the lac operon would you add using sexduction?

a. operator region
b. regulator (repressor)
c. gene promoter region
d. structural genes

Answer 1

The correct option is B: regulator (repressor)

Step-by-step explanation:

A regulator gene would be required to control the expression by either increasing or decreasing the transcription of that particular gene. In doing so, the amount of protein product made by the gene can be regulated. In the wild-type case, the gene lacl is responsible for generating the mRNA which translates to a Lac repressor protein that binds at the operator region.