how does the lac operon "sense" the presence of lactose? Please explain
The lacoperon (lactoseoperon) is an operon required for the transport and metabolism oflactose in Escherichia coli and some other enteric bacteria. It has three adjacent structural genes, lacZ, lacY, and lacA. The genes encode ?-galactosidase, lactose permease, and thiogalactoside transacetylase (or galactoside O-acetyltransferase), respectively. In its natural environment, thelacoperon allows for the effective digestion of lactose.