Question

multiple choice question

what is the inducer of the lactose operon?

galactose
glucose
fructose
lactose

Explanation:

Identify the function of the lactose operon inducer

The lactose operon (lac operon) is an inducible operon that regulates the transport and metabolism of lactose in Escherichia coli and other bacteria. In the absence of lactose, the lac repressor protein binds to the operator, blocking transcription.

Determine the specific inducer molecule

When lactose is present in the environment, a small amount is converted intracellularly into allolactose (an isomer of lactose), or lactose itself acts as the signal. Both bind to the repressor, causing a conformational change that releases it from the operator, thereby inducing transcription of the operon. Among the given choices, lactose is the direct precursor and physiological signal that triggers induction.

Answer:

• Galactose
• Glucose
• Fructose
• Lactose (Correct answer)