Moderate

Which of the following is required as an inducer(s) for the expression of the Lac operon?

Correct answer: A. Lactose

  • A. Lactose
  • B. Lactose and Galactose
  • C. Glucose
  • D. Galactose

Explanation

In the Lac operon, lactose is an inducer. It binds with a suppressor and inactivates it. It allows RNA polymerase to access the promoter, and transcription proceeds. The lac Z, lac Y, and lac genes in the lac operon are the structural genes that code for beta-galactosidase, which converts lactose into glucose and galactose. In the lac operon, Lactose acts as an inducer for the synthesis of protein. Lactose binds with the repressor protein, causing an allosteric shift. This altered repressor cannot bind to the operator, thereby making the promoter region accessible. As the promoter region gets activated, the RNA polymerase enzyme initiates the transcription of the lac operon. Thus, lactose is required for the expression of the lac operon.

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