Question

How does lac operon regulate production of the enzymes needed to metabolize lactose?

Answer 1

lacI, when expressed, produced a repressor protein that negatively controls expression of the lacY and lacZ genes on the operon. The latter two assist in metabolism of lactose by facilitating diffusion and processing it by expressing galactose permease and galactosidase enzymes, respectively.

When there is high glucose concentrations, it will exclude lactose from diffusing through the cell and inhibit cAMP production needed for the cAMP-CAP complex needed to positively control transcription of the lacZ and lacY genes.

Here's a picture if I confused you!