When lactose is plentiful, beta-galactosidase produces allolactose. This binds to the lac repressor and causes it to fall off the DNA, allowing production of enzymes and transporters for lactose utilization. Beta-galactosidase also breaks any extra allolactose into glucose and galactose, so nothing is wasted.

How is beta-galactosidase made?

The presence of lactose results in the synthesis of allolactose which binds to the lac repressor and reduces its affinity for the lac operon. This in turn allows the synthesis of β-galactosidase, the product of the lacZ gene. ... coli that have an active β-galactosidase become blue because of this reaction.

What does beta-galactosidase do in Lac operon?

β-Galactosidase (lacZ) has bifunctional activity. It hydrolyzes lactose to galactose and glucose and catalyzes the intramolecular isomerization of lactose to allolactose, the lac operon inducer.