# Explain the difference between a gene and an allele, and explain how a change in the base sequence of a gene can affect the protein it codes for.

> Eduqas GCSE Biology — 7.1 The genome and gene expression · Explain · 4 marks

## Mark scheme (4 marks)

1. A gene is a section/sequence of DNA that codes for a specific protein / particular characteristic
2. An allele is a different version/form of the same gene
3. A change/mutation in the base sequence of a gene changes the sequence of amino acids in the protein / changes which amino acids are joined together
4. This changes the shape/structure of the protein so it may not function correctly / the active site of an enzyme changes so it no longer works

## Key terms

- [gene](https://www.gradenine.co.uk/glossary/gene)
- [allele](https://www.gradenine.co.uk/glossary/allele)
- [base sequence](https://www.gradenine.co.uk/glossary/base-sequence)
- [protein](https://www.gradenine.co.uk/glossary/protein)

## Related

- [Revision notes for Eduqas GCSE Biology](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-the-difference-between-a-gene-1b015602) · Published by Druglandscape Ltd.