In the lac operon of E. coli, what molecule acts as the inducer that binds to the repressor protein to initiate transcription?
Answer and explanation
Correct answer: A. Allolactose
- Step 1: When lactose enters the bacterial cell, a small amount is converted by beta-galactosidase into allolactose. Step 2. Allolactose binds allosterically to the LacI repressor protein, causing it to dissociate from the operator and allowing transcription. Answer: Allolactose. Why not the others: Glucose exerts catabolite repression; galactose is a cleavage product; tryptophan is corepressor in trp operon.
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