Question

In prokaryotes during the process of gene regulation

i. Lactose suppresses gene expression
ii. Tryptophan acts as an inducer for gene expression
iii. Regulator produces the repressor molecule

• A. i alone is correct
• B. ii and iii are correct
• C. iii alone is correct
• D. iii and i are correct

Answer 1

The correct option is C iii alone is correct

Regulator genes involved in controlling the expression of one or more genes. In operon regulator genes code for the repressor proteins whose presence or absence controls the process of transcription.

Presence of lactose in the growth medium of E. coli induces the lac operon to start the process of transcription so that transport and metabolism of lactose can happen.

Tryptophan operon gets activated when there is deficiency of tryptophan amino acid in a cell. When tryptophan is present in the cell, it binds to the repressor and helps it to bind to the operator and inhibit transcription and thus tryptophan is called the co-repressor.