The trp operon is responsible for encoding genes that synthesize tryptophan, one of the 22 standard amino acids. Operons are composed of multiple associated genes and act as a unit within DNA for genetic expression. An operon is controlled by a single promoter that functions in transcription.
The trp operon is notable for its ability to discern whether or not to produce tryptophan. If tryptophan is already present within the cell, the trp operon is rendered inactive. Jacques Monod discovered the trp operon in 1953 during his work on E. coli. In humans, tryptophan is an essential amino acid, meaning that it cannot be synthesized within the body.