In the lac operon, the z gene codes for :

The lac operon is a set of genes in Escherichia coli that are involved in the metabolism of lactose.

It contains three structural genes: lacZ, lacY, and lacA. Each gene encodes a specific protein:

• lacZ encodes the enzyme beta‑galactosidase, which hydrolyzes lactose into glucose and galactose.

• lacY encodes permease, a membrane protein that facilitates the entry of lactose into the cell.

• lacA encodes transacetylase, whose exact role is less clear but is involved in detoxifying byproducts.

When the question asks “In the lac operon, the z gene codes for :”, the correct answer is the protein produced by the lacZ gene, which is beta‑galactosidase.