‘i’ gene: Codes for the repressor protein, which inhibits transcription of the operon in the absence of lactose.
‘z’ gene: Codes for \(\beta\)-galactosidase, an enzyme that hydrolyses lactose into glucose and galactose.
‘a’ gene: Codes for transacetylase, which transfers an acetyl group to \(\beta\)-galactosides.
‘y’ gene: Codes for lac permease, which facilitates lactose transport into the cell.