Question

The letter 'i ' in the regulatory gene of lac operon refers to ________.

• A. inducer
• B. inhibitor
• C. inheritable
• D. All of the above

Answer 1

The correct option is B inhibitor

Lac operon consists of three structural genes (z, y, and a) and one regulatory gene (i gene). The notation 'i' is derived from the word inhibitor as the i gene codes for the repressor molecule which inhibits the process of transcription. The repressor protein binds to the operator gene and inhibits the RNA polymerse from transcribing the structure genes.

Inducers like lactose regulate switching on and off of the operon; they bind with the repressor protein and it gets inactivated, whereas, in the absence of lactose or a suitable inducer, the repressor binds with the operator region and prevents the process of transcription.