The trp operon and tet operon are classic examples of gene regulation mechanisms in prokaryotes, illustrating how bacteria efficiently control the expression of genes in response to environmental conditions. The trp operon is primarily found in *Escherichia coli* and regulates the biosynthesis of the amino acid tryptophan. It is a repressible operon, meaning that its expression is generally “on” but can be turned “off” when the end product, tryptophan, is abundant. The operon consists of a promoter, an operator, and a series of structural genes (trpE, trpD, trpC, trpB, and trpA) that encode enzymes necessary for tryptophan synthesis. When tryptophan levels are low, the repressor protein, which is synthesized in an inactive form, cannot bind to the operator, allowing RNA polymerase to transcribe the operon and produce the enzymes required for tryptophan synthesis. Conversely, when tryptophan is abundant, it acts as a corepressor by binding to the repressor protein, activating it. The activated repressor then binds to the operator sequence, blocking transcription and preventing unnecessary production of tryptophan. This negative feedback mechanism ensures efficient resource utilization in the cell.