Tryptophan binds to which repressor to regulate the trp operon?

Tryptophan binds to which repressor to regulate the trp operon?

• A. Lac repressor
• B. RNA polymerase
• C. Trp repressor
• D. Promoter

Answer: (C)

Regulation of the trp operon hinges on a repressor that responds to tryptophan levels. Tryptophan binds to the Trp repressor, activating it so it can bind the operator and block RNA polymerase from transcribing the operon. This ensures synthesis of tryptophan is reduced when the amino acid is abundant. When tryptophan is scarce, the repressor is inactive, allowing transcription to proceed. The Lac repressor regulates a different operon, RNA polymerase is the enzyme that performs transcription, and the promoter is the DNA region where RNA polymerase binds—not a repressor.

Regulation of the trp operon hinges on a repressor that responds to tryptophan levels. Tryptophan binds to the Trp repressor, activating it so it can bind the operator and block RNA polymerase from transcribing the operon. This ensures synthesis of tryptophan is reduced when the amino acid is abundant. When tryptophan is scarce, the repressor is inactive, allowing transcription to proceed. The Lac repressor regulates a different operon, RNA polymerase is the enzyme that performs transcription, and the promoter is the DNA region where RNA polymerase binds—not a repressor.