Mutation is a change in the DNA sequence of an organism, due to errors in DNA replication or to damage from physical or chemical agents called mutagens.

A mutated gene may cause a change in the expressed protein, such as the mutant protein that causes curled ears in cats.

Mutations are inherited and persist in the population only if they occur in gamete cells.

Note that most mutations are harmful, but without them, alleles do not arise and evolution does not occur.