Editing Mutation (section)

{{Short description|Alteration in the nucleotide sequence of a genome}}
{{About|the biological term|other uses}}
{{more citations needed|date=September 2023}}
{{Use Oxford spelling|date=November 2024}}
{{Use dmy dates|date=November 2024}}
[[File:Single Chromosome Mutations.svg|thumb|Three major single-chromosome mutations: [[deletion (genetics)|deletion]] (1), [[gene duplication|duplication]] (2) and [[chromosomal inversion|inversion]] (3).]]
{{Genetics sidebar}}

In [[biology]], a '''mutation''' is an alteration in the [[nucleic acid sequence]] of the [[genome]] of an [[organism]], [[virus]], or [[extrachromosomal DNA]].<ref>{{Cite web|publisher=Nature Education |url= https://www.nature.com/scitable/definition/mutation-8|title=mutation {{!}} Learn Science at Scitable|website=Nature|language=en|access-date=24 September 2018}}</ref> Viral genomes contain either [[DNA]] or [[RNA]]. Mutations result from errors during [[DNA replication|DNA]] or [[viral replication]], [[mitosis]], or [[meiosis]] or other types of [[DNA repair#DNA damage|damage]] to DNA (such as [[pyrimidine dimer]]s caused by exposure to [[ultraviolet]] radiation), which then may undergo error-prone repair (especially [[microhomology-mediated end joining]]),<ref>{{cite journal | vauthors = Sfeir A, Symington LS | title = Microhomology-Mediated End Joining: A Back-up Survival Mechanism or Dedicated Pathway? | journal = Trends in Biochemical Sciences | volume = 40 | issue = 11 | pages = 701–714 | date = November 2015 | pmid = 26439531 | pmc = 4638128 | doi = 10.1016/j.tibs.2015.08.006 }}</ref> cause an error during other forms of repair,<ref name="pmid24843013">{{cite journal | vauthors = Chen J, Miller BF, Furano AV | title = Repair of naturally occurring mismatches can induce mutations in flanking DNA | journal = eLife | volume = 3 | pages = e02001 | date = April 2014 | pmid = 24843013 | pmc = 3999860 | doi = 10.7554/elife.02001 | doi-access = free }}</ref><ref name="pmid26033759">{{cite journal | vauthors = Rodgers K, McVey M | title = Error-Prone Repair of DNA Double-Strand Breaks | journal = Journal of Cellular Physiology | volume = 231 | issue = 1 | pages = 15–24 | date = January 2016 | pmid = 26033759 | pmc = 4586358 | doi = 10.1002/jcp.25053 }}</ref> or cause an error during replication ([[DNA repair#Translesion synthesis|translesion synthesis]]). Mutations may also result from [[substitution (genetics)|substitution]], [[Insertion (genetics)|insertion]] or [[Deletion (genetics)|deletion]] of segments of DNA due to [[mobile genetic elements]].<ref name="Bertram">{{cite journal | vauthors = Bertram JS | title = The molecular biology of cancer | journal = Molecular Aspects of Medicine | volume = 21 | issue = 6 | pages = 167–223 | date = December 2000 | pmid = 11173079 | doi = 10.1016/S0098-2997(00)00007-8 | s2cid = 24155688 }}</ref><ref name="transposition764">{{cite journal | vauthors = Aminetzach YT, Macpherson JM, Petrov DA | s2cid = 11640993 | title = Pesticide resistance via transposition-mediated adaptive gene truncation in Drosophila | journal = Science | volume = 309 | issue = 5735 | pages = 764–7 | date = July 2005 | pmid = 16051794 | doi = 10.1126/science.1112699 | bibcode = 2005Sci...309..764A }}</ref><ref name="Burrus">{{cite journal | vauthors = Burrus V, Waldor MK | title = Shaping bacterial genomes with integrative and conjugative elements | journal = Research in Microbiology | volume = 155 | issue = 5 | pages = 376–86 | date = June 2004 | pmid = 15207870 | doi = 10.1016/j.resmic.2004.01.012 | doi-access = free }}</ref>

[[File:Darwin Hybrid Tulip Mutation 2014-05-01.jpg|thumb|A red [[tulip]] exhibiting a partially yellow petal due to a [[somatic mutation]] in a cell that formed that petal]]
Mutations may or may not produce detectable changes in the observable characteristics ([[phenotype]]) of an organism. Mutations play a part in both normal and abnormal biological processes including: [[evolution]], [[cancer]], and the development of the [[immune system]], including [[junctional diversity]]. Mutation is the ultimate source of all [[genetic variation]], providing the raw material on which evolutionary forces such as [[natural selection]] can act.

Mutation can result in many different types of change in sequences. Mutations in [[gene]]s can have no effect, alter the [[gene product|product of a gene]], or prevent the gene from functioning properly or completely. Mutations can also occur in [[Non-gene locus|non-genic region]]s. A 2007 study on [[genetic variation]]s between different [[species]] of ''[[Drosophila]]'' suggested that, if a mutation changes a [[protein]] produced by a gene, the result is likely to be harmful, with an estimated 70% of [[amino acid]] [[Polymorphism (biology)|polymorphism]]s that have damaging effects, and the remainder being either neutral or marginally beneficial.<ref name="Sawyer2007">{{cite journal | vauthors = Sawyer SA, Parsch J, Zhang Z, Hartl DL | title = Prevalence of positive selection among nearly neutral amino acid replacements in Drosophila | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 104 | issue = 16 | pages = 6504–10 | date = April 2007 | pmid = 17409186 | pmc = 1871816 | doi = 10.1073/pnas.0701572104 | bibcode = 2007PNAS..104.6504S | doi-access = free }}</ref>

Mutation and [[DNA damage (naturally occurring)|DNA damage]] are the two major types of errors that occur in DNA, but they are fundamentally different.  DNA damage is a physical alteration in the DNA structure, such as a single or double strand break, a modified guanosine residue in DNA such as [[8-hydroxydeoxyguanosine]], or a [[polycyclic aromatic hydrocarbon]] adduct.  DNA damages can be recognized by enzymes, and therefore can be correctly repaired using the complementary undamaged strand in DNA as a template or an undamaged sequence in a homologous chromosome if it is available.  If DNA damage remains in a cell, [[transcription (biology)|transcription]] of a gene may be prevented and thus translation into a protein may also be blocked.  [[DNA replication]] may also be blocked and/or the cell may die.  In contrast to a DNA damage, a mutation is an alteration of the base sequence of the DNA.  Ordinarily, a mutation cannot be recognized by enzymes once the base change is present in both DNA strands, and thus a mutation is not ordinarily repaired.  At the cellular level, mutations can alter protein function and regulation.  Unlike DNA damages, mutations are replicated when the cell replicates.  At the level of cell populations, cells with mutations will increase or decrease in frequency according to the effects of the mutations on the ability of the cell to survive and reproduce.  Although distinctly different from each other, DNA damages and mutations are related because DNA damages often cause errors of DNA synthesis during replication or repair and these errors are a major source of mutation.<ref>{{cite journal |vauthors=Bernstein H, Byerly HC, Hopf FA, Michod RE |title=Genetic damage, mutation, and the evolution of sex |journal=Science |volume=229 |issue=4719 |pages=1277–81 |date=September 1985 |pmid=3898363 |doi=10.1126/science.3898363 |bibcode=1985Sci...229.1277B |url=}}</ref>