Mutations are changes in the genetic material of a cell. Mutations can be caused by many things, including exposure to radiation or chemicals, or they can occur spontaneously. Most mutations are harmful, but occasionally a mutation will confer an advantage to the organism that carries it. Over time, beneficial mutations can become common in a population through the process of natural selection.
Mutations can affect any part of an organism’s cells, including the genes themselves, the proteins encoded by those genes, and the structure and function of those proteins. A single gene may have multiple forms (alleles) as a result of different mutations. One form may be more advantageous than another in a particular environment; this is known as allelic frequency-dependent selection.
The study of mutations is important for several reasons. First, understanding how mutations occur can help us to develop ways to prevent or repair them. Second, knowledge of mutation rates and patterns can be used to estimate the ages of fossils and DNA sequences. Finally, studying mutant organisms can give us insight into normal development and physiology.