Question

In the lac operon model, lactose, molecules function as

• A. Inducers, which bind with the operator gene.
• B. Repressors, which bind with the operator gene.
• C. Inducers, which bind with the repressor protein.
• D. Corepressors, which bind with repressor protein.

Answer 1

Answer: (C)

Inducers, which bind with the repressor protein.

Lactose of lac operon of E.coli is an example of inducible operon. Lactose is known to be the inducer and substrate for the enzyme $\beta -galactosidase$.
It binds with the repressor protein and changes it into a non-DNA binding state thus activating the operon.