# Proteins are large biological molecules made up of amino acids joined together by peptide bonds. Explain how the structure of a protein is related to its function, referring to the sequence of amino acids and the role of bonds in maintaining the protein's shape.

> Eduqas A-Level Chemistry — 4.7 Amino acids, peptides and proteins · Explain · 5 marks

> Enzymes are proteins that act as biological catalysts. Each enzyme has a specific active site that allows it to bind to only one type of substrate molecule.

## Mark scheme (5 marks)

1. The sequence (order) of amino acids determines the primary structure of the protein
2. The sequence of amino acids determines how the protein folds / the three-dimensional shape of the protein
3. Bonds (e.g. hydrogen bonds / other intermolecular forces / disulfide bonds) hold the protein in its specific shape
4. The specific shape of the active site of an enzyme (protein) means only a complementary substrate can bind
5. If the sequence of amino acids changes / the protein unfolds (denatures), the shape changes and the protein can no longer carry out its function

## Key terms

- [amino acids](https://www.gradenine.co.uk/glossary/amino-acids)
- [peptide bonds](https://www.gradenine.co.uk/glossary/peptide-bonds)

## Related

- [Revision notes for Eduqas A-Level Chemistry](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/proteins-are-large-biological-molecules-made-1dfb3a98) · Published by Druglandscape Ltd.