# A gene mutation can change the base sequence of DNA. Explain how a gene mutation in a body cell could affect the protein produced by that gene, and why a mutation in a gamete is particularly significant for future generations.

> Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 1.5 Gene mutations and genetic disorders · Explain · 5 marks

> Gene mutations are changes to the base sequence of DNA. They can occur spontaneously during DNA replication or be caused by mutagens such as ionising radiation or certain chemicals. Most mutations have no effect on the organism, but some alter the protein coded for by the gene.

## Mark scheme (5 marks)

1. A gene mutation changes the base sequence / order of bases in the DNA
2. The changed base sequence leads to a different sequence of amino acids being coded for
3. A different amino acid sequence means the protein has a different shape / structure, so it may not function correctly
4. A mutation in a gamete (egg or sperm) means the mutation is in the genetic material that is passed on to offspring
5. Every cell of the offspring will contain the mutation / the mutation will be present in all body cells of the offspring, so all generations descended from that individual could inherit it

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Biology A: Salters-Nuffield (9BN0)](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/a-gene-mutation-can-change-the-51781eab) · Published by Druglandscape Ltd.