# Explain why enzymes are proteins and describe how the amino acid sequence of an enzyme determines its function.

> AQA A-Level Biology (7402) — 3.1.4 Proteins and Enzymes · Explain · 5 marks

> Enzymes are large molecules made from chains of amino acids. Each enzyme has a unique three-dimensional shape that is essential for its role in the body.

## Mark scheme (5 marks)

1. Enzymes are proteins (made from amino acids)
2. The sequence / order of amino acids determines the shape of the enzyme
3. Each enzyme has a unique / specific active site shape
4. Only the complementary / matching substrate can fit into the active site (lock and key)
5. This means each enzyme can only catalyse one specific reaction (is specific to one substrate)

## Key terms

- [protein](https://www.gradenine.co.uk/glossary/protein)

## Related

- [Revision notes for AQA A-Level Biology (7402)](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-why-enzymes-are-proteins-and-8e60e5ba) · Published by Druglandscape Ltd.