Final answer:
Lactase catalyzes the hydrolysis of lactose into glucose and galactose, which is essential for lactose digestion. In E. coli, the lac operon regulates lactose utilization and requires lactose to inactivate a repressor that allows enzyme production. A mutation in the repressor could lead to a failure in lactose digestion.
Step-by-step explanation:
The reaction that lactase catalyzes is the hydrolysis of lactose into glucose and galactose. Lactase is an enzyme that is necessary for the digestion of lactose, which is a sugar found in milk. Without lactase, lactose cannot be properly digested, leading to lactose intolerance in many adults. This condition is characterized by gastrointestinal discomfort due to the fermentation of undigested lactose by colon bacteria.
In the context of E. coli, lactose utilization begins with the hydrolysis of lactose by the enzyme β-galactosidase. This enzyme is encoded by the lacZ gene within the lac operon. When lactose is not present, a repressor protein binds to the operator, preventing transcription. When lactose is available, it binds to the repressor, removing it from the operator, and allows RNA polymerase to transcribe the genes needed for lactose utilization.
If there were a mutation in the repressor protein preventing it from binding lactose, the lac operon would not be activated in the presence of lactose, leading to an inability to digest and utilize lactose efficiently.