# Explain how allosteric regulation allows an enzyme to act as a metabolic switch, using the concept of cooperativity where relevant.

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

## Mark scheme (4 marks)

1. Allosteric regulators bind at a site other than the active site (the allosteric site), causing a conformational change in the enzyme.
2. This conformational change alters the shape of the active site, either increasing (activator) or decreasing (inhibitor) enzyme activity, effectively switching catalytic activity on or off.
3. Many allosteric enzymes are multimeric (have multiple subunits); binding of a substrate or effector to one subunit induces conformational changes in adjacent subunits — this is cooperativity.
4. Allosteric regulation commonly operates as end-product (feedback) inhibition, where the final product of a metabolic pathway inhibits an earlier allosteric enzyme, preventing overproduction and conserving cellular resources.

## Key terms

- [allosteric regulation](https://www.gradenine.co.uk/glossary/allosteric-regulation)
- [cooperativity](https://www.gradenine.co.uk/glossary/cooperativity)

## 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-allosteric-regulation-allows-an-6aa8bb09) · Published by Druglandscape Ltd.