A mutant E. coli strain is found that synthesizes $\beta$-galactosidase in the absence of glucose whether or not lactose is present. What two mutations might lead to this outcome? A) lacI^s mutation or lacO^c mutation B) lacP^- mutation or lacI^- mutation C) lacP^- mutation or lacO^c mutation D) lacI^- mutation or lacO^c mutation E) lacP^- mutation or lacI^s mutation

Question

Quizplus · Accepted Answer

The lacI^- mutation results in a non-functional repressor, allowing expression of the lac operon regardless of lactose presence. The lacO^c mutation alters the operator sequence, preventing the repressor from binding and allowing constitutive expression.

A Mutant E β\betaβ -Galactosidase in the Absence of Glucose Whether or Not Lactose

A Mutant E $\beta$ -Galactosidase in the Absence of Glucose Whether or Not Lactose