Components and analogs of the lac operon are used by researchers as experimental tools. Match the molecule with its activity.
-allolactose

Question

Quizplus · Accepted Answer

Allolactose derepresses the lac operon when lactose is present in the cell, by binding to the lac repressor and preventing it from binding to the operator.

Answer: A
 The lac repressor binds to the operator region of the lac operon in the absence of lactose, preventing RNA polymerase from binding and transcribing the genes involved in lactose metabolism. Allolactose binds to the repressor, causing it to release from the operator and allowing transcription to occur.

Answer: D
 Beta-galactosidase is the enzyme involved in breaking down lactose into glucose and galactose. It is encoded by the lacZ gene in the lac operon.

Answer: C
 Beta-galactosidase catalyzes the hydrolysis of lactose into glucose and galactose, but it also cleaves a phosphate group from the substrate ONPG (ortho-nitrophenyl beta-D-galactopyranoside), producing a blue color. This activity is frequently used as a reporter gene to assay for the activity of the lac operon.

Components and Analogs of the Lac Operon Are Used by Researchers