BRAINCAKEDifferent Types of Mutation
Gene mutations that affect one or a few bases are called point mutations. There are three main types.
Substitution: one base is replaced by a different base. Only one codon changes, so at most one amino acid is affected. Because the genetic code is degenerate, the new codon may code for the same amino acid (a silent mutation). It may code for a different amino acid (a missense mutation), as in sickle cell anaemia, where a substitution changes glutamic acid to valine in the β-globin chain. It may also create a stop codon (a nonsense mutation), which gives a shortened, usually non-functional protein.
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Key terms in this lesson
- degenerate
- Describes a genetic code in which more than one codon can code for the same amino acid.
More in Genetic Information
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- Random Fertilisation
- Genetics and Inheritance
- Alleles
- Polygenic Traits
- Monohybrid Crosses
- Test Cross
All 30 lessons in Genetic Information · All Edexcel A-level Biology topics