# Explain how the sequence of amino acids in a protein determines its specific three-dimensional shape, and why this shape is important for the protein's function. Use your knowledge of protein structure to support your answer.

> WJEC A-Level Chemistry (Wales) — 4.7 Amino acids, peptides and proteins · Explain · 5 marks

> Enzymes are proteins that act as biological catalysts. A change in just one amino acid in an enzyme can destroy its ability to catalyse a reaction.

## Mark scheme (5 marks)

1. The sequence (order) of amino acids in a protein is determined by the genetic code / DNA
2. The sequence of amino acids causes the protein chain to fold into a specific three-dimensional shape
3. Each protein has a unique / specific shape (tertiary structure) that is essential for its function
4. For an enzyme, the specific shape forms an active site that is complementary to the substrate
5. If the amino acid sequence changes, the shape of the protein changes and it can no longer function correctly

## Key terms

- [three-dimensional shape](https://www.gradenine.co.uk/glossary/three-dimensional-shape)
- [function](https://www.gradenine.co.uk/glossary/function)

## Related

- [Revision notes for WJEC A-Level Chemistry (Wales)](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-the-sequence-of-amino-8b9ff32f) · Published by Druglandscape Ltd.