The mmm operon, which has sequences a, b, c, and d, encodes enzymes 1 and 2. mutations in sequences a, b, c, and d have the following effects, where a plus sign (+) means that the enzymes are synthesized, a minus sign (−) means that the enzymes are not synthesized, and a pound (#) means that the enzymes are synthesized but are not functional.

mmm absent mmm present

enzyme 1 enzyme 2 enzyme 1 enzyme 2

wild-type + + − −

mutation in a # + − −
mutation in b + + + +
mutation in c + # −
mutation in d − − − −

(a) is the mmm operon inducible or repressible? explain your answer.
(b) indicate which sequence (a, b, c, or d) is part of the following components of the operon and explain your answer.

regulator gene:

promoter:

structural gene for enzyme 1:
structural gene for enzyme 2: