BRAINCAKEMutations
A mutation is a change in the base sequence of DNA. Mutations are the only source of completely new alleles, so they are the original source of all genetic variation in a gene pool.
Gene mutations include substitution, insertion and deletion of bases. Unless a multiple of three bases is involved, insertions and deletions cause a frame shift, altering every codon after the mutation. Larger chromosome mutations change the structure or number of chromosomes. Mutations happen spontaneously during DNA replication, and the rate is increased by mutagens such as ionising radiation, ultraviolet light and some chemicals, for example those in tobacco smoke.
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More in Gene Pools
- Allele Frequency
- Hardy Weinberg Equilibrium
- Hardy Weinberg Equation
- Conditions of the Hardy Weinberg Equilibrium
- Non-Random Mating
- Different Sized Populations
- Isolation
- Selection Pressure
All 16 lessons in Gene Pools · All Edexcel A-level Biology topics