# Explain how end-product inhibition allows a cell to regulate the rate of a metabolic pathway.

> IB DP Biology Higher Level (2023 syllabus) — C1.1 Enzymes and metabolism · Explain · 4 marks

> In many biosynthetic pathways, the final product of the pathway acts as an inhibitor of an enzyme that catalyses an early step in the same pathway.

## Mark scheme (4 marks)

1. The end-product of the pathway binds to an allosteric site on an enzyme that catalyses an early (committed) step in the pathway.
2. Binding of the end-product causes a conformational change in the enzyme, reducing its catalytic activity (allosteric inhibition).
3. When the concentration of the end-product is high, the pathway is inhibited, reducing further synthesis of that product.
4. When the end-product is consumed / its concentration falls, inhibition is relieved and pathway activity resumes, acting as a negative feedback mechanism to match production to demand.

## Key terms

- [end-product inhibition](https://www.gradenine.co.uk/glossary/end-product-inhibition)
- [metabolic pathway](https://www.gradenine.co.uk/glossary/metabolic-pathway)

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-end-product-inhibition-allows-a-388b9203) · Published by Druglandscape Ltd.