Answer
The following are the probable effects on
gene expression in the lac operon of a mutation
Work Step by Step
(a) constitutive, low-level expression of the operon: most mutations in the operator would make the repressor less likely to bind.
(b) either constitutive expression, as in(a), or constant repression, if the mutation destroyed the capability to bind to lactose and related compounds, thus destroying the response to inducers.
(c) either increased or decreased expression of the operon(under conditions in which it is included), depending on whether the mutation made the promoter more or less similar, respectively, to the consensus E.coli promoter.
