Question

How are the structural genes activated in the lac operon in E.coli?

Answer 1

In Lac operon model, lactose is a primary inducer which activates the structural genes. In presence of lactose the repressor gets deactivated and the RNA polymerase binds to the operator to promote the the translation of m-RNA strands into the relevant proteins by the structural genes. The proteins encoded by the structural genes are as follows-

lacZ encodes β-galactosidase (LacZ), lacY encodes lactose permease (LacY), LacA encodes galactoside O-acetyltransferase (LacA)