# Proteins are natural polymers formed from amino acid monomers. Explain how amino acids join together to form a polypeptide, and describe two structural features of DNA that show it is also a polymer.

> AQA A-Level Chemistry (7405) — 3.3.13 Amino acids, proteins and DNA (A-Level only) · Explain · 5 marks

## Mark scheme (5 marks)

1. Amino acids join together by condensation polymerisation
2. Water is lost/released when amino acids join together
3. Amino acids have two functional groups (that allow them to form a chain / react with two other monomers)
4. DNA is made from nucleotide monomers (nucleotides are the monomers of DNA)
5. DNA consists of two polymer chains in the form of a double helix

## Key terms

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

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/proteins-are-natural-polymers-formed-from-a44f7d04) · Published by Druglandscape Ltd.