Mutations
Biology: Cambridge International GCSE Supplement, topic 18.1.3
Mutations
In sexually reproducing populations, many different combinations of alleles are present, meaning that variation is high. Whilst sexual reproduction is capable of shuffling pre-existing alleles, only mutations (genetic changes) can generate new alleles.
What rate do mutations happen at?
- Mutations are rare.
- The rate of mutations can be increased by ionising radiation and some chemicals.
Do mutations always affect the phenotype?
- Most mutations do not affect the phenotype.
- Of the small number that do affect the phenotype, it is rare that the phenotypic change will give a significant survival advantage.
- If a new mutation generates a new phenotype that's more adapted to a recent environmental change than the rest of the population, the mutation will likely spread throughout the population over a small number of generations.
Test yourself on Mutations
How frequently do mutations happen?
Which of the following processes can generate new alleles?
Which of the following are true of mutations?