Mutations

These are spontaneous, natural, or artificially induced hereditary genetic material changes that trigger changes in certain characteristics of the organism. Depending on the nature of the genetic material alteration, mutations can be point mutations, insertions, aberrations, and changes in the number of chromosomes. Point mutations involve the deletion or insertion of nucleotides, possible changes in the positions of DNA nucleotide pairs – transition and transversion. This can alter the functions of genes or several adjacent genes of one operon. Insertions are the insertion of DNA molecules into a gene, which inactivates the gene. Chromosomal rearrangements are possible due to non-homologous recombination of genetic material regions. These include deletions, inversions, duplications, translocations, transpositions – the transfer of genetic material between chromosomes or within the same chromosome. The number of chromosomes in a cell can change (polyploidy). Mutations are often classified as gene, chromosomal, and genomic, depending on the level of genetic information carrier. Gene mutations include all point mutations, while agenomic mutations involve changes in the number of chromosomes. Chromosomal aberrations can be attributed to gene or agenomic mutations, depending on the size of the affected fragment (aberration). Mutations are characteristic of all living organisms.

They occur when the normal processes of duplication (reduplication), recombination, and repair (reparation) are disrupted by a mutagen. Spontaneous mutations occur as errors in genetic material replication because duplication does not occur absolutely accurately, and repair is not absolutely efficient. Gene mutations are the most common of all mutations, causing various characteristic changes. Most often, they are harmful to the organism because a mutant gene can trigger an inherited disease, deformity, or even the death of a developing organism.

Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė