The lac operon comprises the following genes and their encoded products:
'i' gene: Encodes the repressor protein (iii).
'z' gene: Encodes $\beta$-galactosidase (i), responsible for lactose breakdown.
'a' gene: Encodes transacetylase (iv).
'y' gene: Encodes lac permease (ii), which aids in lactose transport into the cell.