# Proteins are large molecules that are essential for life. Describe the structure of a protein, starting from its amino acid building blocks.

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

## Mark scheme (5 marks)

1. Proteins are made up of (many) amino acids
2. Amino acids are joined together by peptide bonds
3. A condensation reaction occurs when amino acids join / water is released when amino acids join
4. Two amino acids joined together form a dipeptide / a small number of amino acids joined together form a peptide
5. A long chain of many amino acids forms a polypeptide / protein

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Chemistry (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/proteins-are-large-molecules-that-are-3fadb9f6) · Published by Druglandscape Ltd.