<P> Bacterial operons are polycistronic transcripts that are able to produce multiple proteins from one mRNA transcript . In this case , when lactose is required as a sugar source for the bacterium , the three genes of the lac operon can be expressed and their subsequent proteins translated : lacZ , lacY , and lacA . The gene product of lacZ is β - galactosidase which cleaves lactose , a disaccharide , into glucose and galactose . lacY encodes Beta - galactoside permease , a protein which becomes embedded in the cytoplasmic membrane to enable transport of lactose into the cell . Finally , lacA encodes β - galactoside transacetylase . </P>
what the role of the protein encoded by the lacz gene
cleaves lactose , a disaccharide , into glucose and galactose