Explain how mutation occurs in DNA. List examples of what occurs when DNA mutates.

Mutation occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene. A Mutagen is an agent of substance that can bring about a permanent alteration to the physical composition of a DNA gene such that the genetic message is changed

What is the example? i’ll be happy to answer if you can tell me : )

Nine months old i think but i’m not that sure