Mutations and genetic variationSpec 3.22, 3.23
A mutation is a change in the base sequence of DNA. There is usually extensive genetic variation within a population of a species, and this variation arises through mutations.
Mutations affect the phenotype in different ways:
- Most genetic mutations have no effect on the phenotype.
- Some mutations have a small effect on the phenotype.
- Rarely, a single mutation will significantly affect the phenotype.