Question

Which of the following genes is not transcribed from the promoter for $\beta$ -galactosidase?

• A. Lac-Z
• B. Lac-i
• C. Lac-Y
• D. Lac-A

Answer 1

The correct option is B Lac-i

Answer is option B i.e. "Lac-i"
The Lac-i gene synthesizes Lac-i repressor protein. In the absence of lactose, the Lac-i repressor protein acts as a repressor of transcription from the lac promoter. Transcription begins when lactose binds to Lac-i, which results in the expression of three genes ( Lac-Z, Lac-Y and Lac-A) involved in lactose uptake and catabolism.