Now a specific example of a repressible Operon used by bacterial cells is a tryptophan Operon. So what exactly is a repressible Operon? Well, a repressible Operon is the most common type of Operon used by bacterial cells in anabolic processes. And a repressible opera is usually on, but sometimes under certain circumstances it can be turned off as we'll see in just a moment. So a tryptophan Operon is an Operon that is used by bacterial cells to basically regulate the synthesis of the tryptophan amino acid. So let's take a look at the different components of the tryptophan opera.