The Lac Operon of E

Multiple Choice

The lac operon of E. coli controls the transcription of three genes needed in lactose metabolism: the lacZ gene, which encodes β- galactosidase; the lacY gene, which encodes permease; and the lacA gene, which encodes thiogalactoside transacetylase. The lac operon is negative inducible: a regulator gene produces a repressor that binds to the operator site and prevents the transcription of the structural genes. The presence of allolactose inactivates the repressor and allows the transcription of the lac operon.
-In the presence of allolactose, the lac repressor

A) binds to the operator.
B) binds to the promoter.
C) cannot bind to the operator.
D) binds to the regulator gene.