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The lac operon consists of
A
Four regulatory genes only
B
One regulatory gene and three structural genes
C
Two regulatory genes and two structural genes
D
Three regulatory genes and three structural genes
Detailed Solution
The lac operon is a polycistronic unit in which the structural genes are regulated by a common promoter and regulatory gene.
It has one regulatory gene, the i gene (i for inhibitor), which codes for the repressor.
It has three structural genes: z codes for β-galactosidase, which hydrolyses lactose into galactose and glucose; y codes for permease, which increases the permeability of the cell to β-galactosides; a codes for transacetylase.
Hence the lac operon consists of one regulatory gene and three structural genes.
It has one regulatory gene, the i gene (i for inhibitor), which codes for the repressor.
It has three structural genes: z codes for β-galactosidase, which hydrolyses lactose into galactose and glucose; y codes for permease, which increases the permeability of the cell to β-galactosides; a codes for transacetylase.
Hence the lac operon consists of one regulatory gene and three structural genes.