A mutation is the change in the sequence of a nucleotide or in the organization of the DNA (genotype) of a living being, which produces a variation in the characteristics of this and that is not necessarily transmitted to the offspring. It occurs spontaneously and suddenly or by the action of mutagens. This change will be present in a small proportion of the population (variant) or of the organism (mutation). The genetic unit capable of mutating is the gene, the unit of hereditary information that is part of DNA.
In multicellular beings, mutations can only be inherited when they affect the reproductive cells. A consequence of mutations can be, for example, a genetic disease. However, although in the short term they may seem harmful, mutations are essential for our long-term existence. Without mutation there would be no change, and without change life could not evolve.
The definition of mutation from the knowledge that the hereditary material is DNA and the proposal of the double helix to explain the structure of the hereditary material (Watson and Crick, 1953), would be that a mutation is any change in the sequence of nucleotides of DNA. When this mutation affects a single gene, it is called a gene mutation. When it is the structure of one or more chromosomes that is affected, chromosomal mutation. And when one or several mutations cause alterations in the whole genome they are called genomic mutations.
