In lac operon, the lactose is transported into the bacterial cells with the help of:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Permease
The lac operon has a regulatory gene (i) and three structural genes (z, y and a). The y gene codes for permease, a membrane protein. It increases the permeability of the cell, so lactose can be taken into the bacterial cell.
(1) β-galactosidase — Incorrect. It is made by the z gene. It works inside the cell and breaks lactose into glucose and galactose. It does not carry lactose in.
(2) Transacetylase — Incorrect. It is made by the a gene. Its function is not to transport lactose.
(3) Permease — Correct. It brings the lactose into the cell. This is the first step, because the inducer must enter the cell before it can switch on the operon.
(4) Repressor — Incorrect. It is made by the i gene. It binds to the operator and switches the operon off. It does not transport anything.
NCERT Extract:
The Lac Operon – …
