Match List-I with List-II
|
List-I Genes of lac Operon |
List-II Codes for |
|
(A) $i$ |
(I) β-galactosidase |
|
(B) $z$ |
(II) Transacetylase |
|
(C) $a$ |
(III) Permease |
|
(D) $y$ |
(IV) Repressor |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A)-(IV), (B)-(I), (C)-(II), (D)-(III)
|
List-I Genes of lac Operon |
List-II Codes for |
|
(A) $i$ |
(IV) Repressor |
|
(B) $z$ |
(I) β-galactosidase |
|
(C) $a$ |
(II) Transacetylase |
|
(D) $y$ |
(III) Permease |
The lac operon consists of one regulatory gene (the i gene – here the term i does not refer to inducer, rather it is derived from the word inhibitor) and three structural genes (z, y, and a). The i gene codes for the repressor of the lac operon. The z gene codes for beta-galactosidase ( β-gal), which is primarily responsible for the hydrolysis of the disaccharide, lactose into its monomeric units, galactose and glucose. The y gene codes for permease, which increases permeability of the cell to β-galactosides. The a gene encodes a transacetylase. Hence, all the three gene products in lac operon are required for metabolism of lactose
Lactose is the substrate for the enzyme beta-galactosidase and it regulates switching on and off of the operon. Hence, it is termed as inducer.