Question

Match the following genes of the Lac-operon with their respective products:

(a) i gene	(i) 𝞫- galactosidase
(b) z gene	(ii) Permease
(c) a gene	(iii) Repressor
(d) y gene	(iv) Transacetylase

Select the correct option
A. (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
B. (a)-(iii), (b)-(i), (c)-(ii), (d)-(iv)
C. (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)
D. (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)

Answer 1

Hint: The lac-operon is a group of genes. The group of genes are responsible for the metabolism and transport of Lactose in many enteric bacteria and E.coli. The process happens when glucose is not available as the energy source.

Complete step by step answer: The Lac-operon consists of three structural genes that code for different enzymes. The i gene is the one coding for the Repressor protein. The i in the name stands for Inducer, it has the ability to turn off the expression of the gene, and it prevents the formation of messenger RNA. This inhibits the process of transcription in the Lac operon. The z gene codes for beta-galactosidase, the gene responsible for the catalysis of the hydrolysis of lactose into glucose and galactose. The y gene is which codes for permease enzyme and facilitates and regulates the permeability of lactose into the cells. The gene codes for transacetylase enzyme, whose function is to facilitate the functioning of- galactosidase by transferring an acetyl group from Acetyl-CoA to galactosidase necessary for lactose catabolism.

In the process, lactose acts as an inducer. The presence of lactose in the medium, it can activate the
regulatory gene. The inducer binds to the repressor gene and makes it inactive. Thus it is a negatively regulated process.
Thus, the correct answer is option C.

Note: Operons are present only in prokaryotes and are absent in eukaryotic organisms. The various types of operons are Lac operon involved in lactose degradation, Trp operon involved in tryptophan biosynthesis, and His operon involved in Histidine biosynthesis.