What is the trp operon and how is it repressed?

The trp operon is a repressible operon that is turned off by the binding of tryptophan to the trp R repressor.

The trp operon is repressed by the lack of oxygen.

The trp operon is an inducible operon that is always on unless turned off by lactose.

The trp operon is repressed by high levels of glucose.