Question

Which of the following is the correct statement for regulation of gene expression in prokaryotes?

A. Lactose acts as the suppressor for gene expression.

B. Tryptophan acts as the inducer for gene expression.

C. Regulator gene is the one that produces the repressor molecule.

• A. A alone correct
• B. B alone correct
• C. C alone correct
• D. B and A are correct
• E. B and C are correct

Answer 1

Answer: (C)

C alone correct

• Lactose serves as an inducer, not as a suppressor for lac operon. Lac operon is on in presence of lactose.
• Tryptophan serves as a corepressor, inhibiting the expression of the structural genes present in the tryptophan operon.
• The regulator gene regulates the expression of structural genes by its protein product that is known as repressor molecule.

Thus, the correct answer is option C.