Question

Select the two correct statements out of the four (A to D) given below about lac operon.

(A) Glucose or galactose may bind with the repressor and inactivate it.
(B) In the absence of lactose, the repressor binds with the operator region.
(C) The z-gene codes for permease.

(D) This was elucidated by Francois Jacob and Jacque Monod.

• A. (A) and (B)
• B. (B) and (C)
• C. (A) and (C)
• D. (B) and (D)

Answer 1

Answer: (D)

(B) and (D)

Lac operon was elucidated by the Francois Jacob and Jacque Monod. The lac operon is the mechanism to control the production of the enzymes encoded by the lac operon only when necessary. In the absence of lactose, the lac repressor halts production of the enzymes encoded by the lac operon. The three structural genes in the lac operon can be expressed and their subsequent proteins translated: lacZ, lacY and lacA. The gene product oflacZ is β-galactosidase.lacY encodes permease and lacA encodes transaminase. Thus, the correct answer is option D.