Tryptophan

Definition

Tryptophan is an essential amino acid that serves as a precursor for the synthesis of proteins and serotonin. In gene regulation, it plays a critical role in the tryptophan operon system in prokaryotes.

5 Must Know Facts For Your Next Test

1. Tryptophan is involved in the feedback inhibition mechanism of the tryptophan operon in E. coli.
2. The tryptophan operon consists of five structural genes that are regulated by the availability of tryptophan.
3. When tryptophan levels are high, it binds to the trp repressor protein, activating it to bind to the operator site and block transcription.
4. In low tryptophan conditions, the trp repressor is inactive, allowing RNA polymerase to transcribe the operon's genes.
5. The regulation mechanism of the tryptophan operon is an example of negative feedback.

Review Questions

• What role does tryptophan play in the regulation of its own synthesis in prokaryotes?
• How does tryptophan interact with the trp repressor protein?
• Describe what happens to the transcription of the tryptophan operon when intracellular levels of tryptophan are low.

Related terms

trp Operon: A group of genes involved in the biosynthesis of tryptophan in bacteria.

trp Repressor: A regulatory protein that binds to DNA and inhibits gene expression when activated by binding to tryptophan.

Feedback Inhibition: A regulatory mechanism wherein an increase in substrate or end product inhibits further production.