The hereditary information of the cell is recorded as the nucleotide sequence of DNA. There are mechanisms to protect DNA from external influences in order to avoid a violation of genetic information. However, such violations occur regularly, and they are called mutations. Mutations are changes that have arisen in the genetic information of a cell, and these changes can have a different scale and are divided into types. Genomic mutations – changes regarding the number of whole chromosomes in the genome, such as Down’s syndrome, where the number of total chromosomes more than normal. Gene mutations are changes that occur within a single gene, such as sickle-cell anemia. Chromosomal mutations – changes that affect areas within the same chromosome.
Chromosomal mutations are divided into species as a deletion, which is a loss of a chromosome region, and duplication, which is a doubling of a chromosome region. Inversion is a rotation of the chromosome region by 180-degrees, as a result of which the genes in this region are located in the reverse order compared to normal. Translocation is the movement of any part of the chromosome to another place. With deletions and duplications, the total amount of genetic material changes, the degree of phenotypic manifestation of these mutations depends on the size of the changed sites, as well as on how important genes got into these areas. With inversions and translocations, a change in the amount of genetic material does not occur; only its location changes. Such mutations are needed evolutionarily since mutants often can no longer interbreed with the original individuals.