Gene mutations are most commonly caused as a result of two types of occurrences. Environmental factors such as chemicals, radiation, and ultraviolet light from the sun can cause mutations. These mutagens alter DNA by changing nucleotide bases and can even change the shape of DNA. These changes result in errors in DNA replication and transcription.

A mutation is any change to the nucleotide sequence of a DNA molecule. Some mutations arise as DNA is copied. Others are due to environmental factors. A mutation in a gene can change the structure and function of the protein encoded by that gene. This, in turn, can affect an organism’s traits.