Question

Genes that are involved in turning on or off the transcription of a set of a structural genes are called

• A. Redundant genes
• B. Regulatory genes
• C. Polymorphic genes
• D. Operator genes

Answer 1

Answer: (D)

Operator genes

Lac operon is made up of regulator, operator and structural gene. The regulator gene produces m-RNA which translates into the repressor. The repressor attaches to the operator and blocks the expression of the structural gene in absence of inducer. In presence of inducer, the repressor attaches to the inducer and operator is not blocked so it allows the expression of the structural gene.

Operator genes are a region of DNA sequence which attaches to the repressor molecule and stops the expression of the structural gene.

So, the correct answer is option D.