IGCSEBiologyEdexcelBiology (Modular)Unit 2Revision Notes4. Reproduction & InheritanceInheritanceMutation

Mutation (Edexcel IGCSE Biology (Modular): Unit 2): Revision Note

Exam code: 4XBI1

Written by: Lára Marie McIvor

Reviewed by: Lucy Kirkham

Updated on 2 July 2026

Mutations

Mutations are rare, random changes that occur in the sequence of DNA bases in a gene or a chromosome
Mutations can be inherited
They occur continuously
As the DNA base sequence determines the sequence of amino acids that make up a protein, mutations in a gene can sometimes lead to a change in the protein that the gene codes for
- Most mutations do not alter the protein or only alter it slightly so that its appearance or function is not changed

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Author: Lára Marie McIvor

Expertise: Content Creator

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.

Reviewer: Lucy Kirkham

Expertise: Content Creator

Lucy has been a passionate Maths teacher for over 12 years, teaching maths across the UK and abroad helping to engage, interest and develop confidence in the subject at all levels.Working as a Head of Department and then Director of Maths, Lucy has advised schools and academy trusts in both Scotland and the East Midlands, where her role was to support and coach teachers to improve Maths teaching for all.