Which one of the following is a inhibitor genes in lac operon?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Gene i
The lac operon has one regulatory gene and three structural genes. The regulatory gene is the i gene. Its name comes from the word inhibitor, and it does not mean inducer. It codes for the repressor of the operon.
(1) Gene i — Correct. It is the inhibitor gene. Its repressor protein blocks the operon until lactose, the inducer, arrives.
(2) Gene z — Incorrect. It is a structural gene. It codes for beta-galactosidase, the enzyme that splits lactose into galactose and glucose.
(3) Gene y — Incorrect. It is a structural gene. It codes for permease, which increases the permeability of the cell to beta-galactosides.
(4) Gene a — Incorrect. It is a structural gene. It codes for a transacetylase.
NCERT Extract:
The Lac Operon – …
