How does a mutagen induce mutation? Explain with example.

An agent such as chemical or physical factors, UV radiation which results in alterations in DNA sequences and consequently results in changes in phenotype and genotype of an organism is called mutagen. A mutagen can change the alignment and composition of nitrogen bases of DNA that results in changed product of gene (thus bring about mutation).

For example chemical mutagens such as ethylmethanesulfonate (EMS) and X-rays can both be used to induce pseudorandom mutations into the genome of fly. EMS typically causes single base pair changes while X rays often results in deletion and gross chromosomal rearrangements.