Question

Select the two statements out of the four (I-IV) given below about lac operon.

I. Glucose or galactose may bind with the repressor and inactivate it.

II. In the absence of lactose, the repressor binds with the operator region.

III. The z-gene codes for permease.

IV. This was elucidated by Francois Jacob and Jacques Monod.

The correct statements are

(a) I and III

(b) I and III

(c) II and IV

(d) I and II

Answer 1

Correct option (c) II and IV

Explanation

Statement II and IV are true about lac operon. In prokaryotes, a hypothesis was given in 1961 to explain the protein synthesis regulation. This hypothesis was given by F Jacob and J Monod and for this they were awarded Nobel prize in 1965, the hypothesis was known by the name of Operon Model. 

The operator gene is the segment of DNA, which exercise a control over transcriptions. In the absence of lactose, the repressor binds with the operator gene.