An E. coli cell without a functional lacI gene is expected to ________.
A) never produce β-galactosidase
B) always produce β-galactosidase
C) be unable to transport lactose into the cell
D) be unable to metabolize lactose within the cell

Question

Quizplus · Accepted Answer

The lacI gene encodes for the lac repressor protein that binds to the operator region of the lac operon, inhibiting transcription of the lac genes. If the lacI gene is not functional, there will be no inhibition of the lac operon and β-galactosidase will always be produced in the presence of lactose. Therefore, choice B is the correct answer. Choices A, C, and D are incorrect because the absence of a functional lacI gene does not affect the production, transport, or metabolism of lactose in E. coli cells.

An E Coli Cell Without a Functional LacI Gene Is Expected