Amutation is a change in a genetic sequence. Mutations include changes as smallas the substitution of a single DNA building block, or nucleotide base, withanother nucleotide base. Meanwhile, larger mutations can affect many genes on achromosome. Along with substitutions, mutations can also be caused byinsertions, deletions, or duplications of DNA sequences.
Somemutations are hereditary because they are passed down to an offspring from aparent carrying a mutation through the germ line, meaning through an egg orsperm cell carrying the mutation. There are also nonhereditary mutations thatoccur in cells outside of the germ line, which are called somatic mutations.Mutations can be introduced due to mistakes made during DNA replication or dueto exposure to mutagens, which are chemical and environmental agents that canintroduce mutations in the DNA sequence, such as ultraviolet light. Some mutationsdo not result in changes in the amino acid sequence of the encoded protein andcan be described as silent mutations. Other mutations result in abnormalprotein products. Mutations can introduce new alleles into a population oforganisms and increase the population's genetic variation.
