What Type of Operon is the Trp Operon

Question

What type of operon is the trp operon?
A) Positive repressible operon
B) Negative repressible operon
C) Positive inducible operon
D) Negative inducible operon
E) Constitutive inducible operon

Accepted Answer

The trp operon is a negative repressible operon, meaning that it is normally turned on (transcription occurs) but can be turned off (repressed) when the end product of the pathway, tryptophan, binds to the repressor protein and activates it to bind to the operator site, preventing RNA polymerase from transcribing the genes.