What is the trp operon and how is it repressed?

• A. The trp operon is a repressible operon that is turned off by the binding of tryptophan to the trp R repressor.
• B. The trp operon is repressed by the lack of oxygen.
• C. The trp operon is an inducible operon that is always on unless turned off by lactose.
• D. The trp operon is repressed by high levels of glucose.

Answer: (A)