Mutation: GCSE Biology Definition

What is a mutation?

In GCSE biology a mutation is a random change in the sequence of DNA bases in a gene or a chromosome. When the genetic code mutates bases can be added, removed or moved to a different location in the chromosome.

Mutations can occur due to random errors during DNA replication. The rate at which mutations occur can increase with exposure to mutagenic agents, such as UV radiation.

The sequence of DNA bases determines the sequence of amino acids in proteins, meaning that a mutation may result in a change in the phenotype of an individual. The effect of mutations can be:

• negative: protein structure changes and the new function, or lack of function, in the altered protein is harmful to an organism

• neutral: protein structure is unaffected

• positive: protein structure changes and the altered protein provides a survival advantage to an organism

Mutation revision resources to ace your exams

You can learn more about mutations in our GCSE biology revision notes:

• DNA structure (AQA GCSE Biology)

• Mutations (Edexcel GCSE Biology)

• Genetic Variation Within a Population (OCR Gateway GCSE Biology)

• Mutations (WJEC GCSE Biology) 

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GCSE Biology Revision Resources