Question

Constitutive gene in Lac operon is
(A) i-gene
(B) 0-gene
(C) Z-gene
w
(D) y-gene
A
B
C​

Answer 1

Answer:

a) i-gene may be the answer.............

Answer 2

Answer:

(A) i-gene

Explanation:

Lac Operon

“Lac operon is an operon or a group of genes with a single promoter that encode genes for the transport and metabolism of lactose in E.coli and other bacteria.”

Lac Operon Concept

Gene regulation in prokaryotes can be explained with the help of the Lac Operon model. Here the alteration in physiological and environmental conditions can be observed leading to an alteration in expression in prokaryotes. It was observed by Jacob and Monod. The lac operon consists of:

Regulatory gene i – It codes for the repressor protein.

z gene – It codes for beta-galactosidase which catalyzes the hydrolysis of lactose into glucose and galactose.

y gene – It codes for permease which regulates the lactose permeability in the cell.

a gene – It codes for transacetylase which assists the enzyme beta-galactosidase.

Hence, all these genes help in lactose metabolism. In lac operon, lactose acts as an inducer. If lactose is provided in the medium for the bacteria, the regulatory gene is activated. The inducer will bind to the repressor protein and render it inactive which allows transcription of the operon. Thus, the lac operon is negatively regulated in this case.

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