Question

Give an example of enzyme repression.

Answer 1

Example: tryptophan operon

When tryptophan is scarce, the operon is active and its structural genes direct the production of enzymes needed to synthesise tryptophan. When tryptophan is abundant, it binds to the repressor protein and acts as a co-repressor. The resulting functional repressor complex binds to the operator and blocks transcription of the structural genes.

Therefore, the end product—tryptophan—switches off the genes for its own synthesis by activating the repressor.