Editing DNA (section)

=== Artificial bases ===
{{Main|Nucleic acid analogue}}

Several artificial nucleobases have been synthesized, and successfully incorporated in the eight-base DNA analogue named [[Hachimoji DNA]]. Dubbed S, B, P, and Z, these artificial bases are capable of bonding with each other in a predictable way (S–B and P–Z), maintain the double helix structure of DNA, and be transcribed to RNA. Their existence could be seen as an indication that there is nothing special about the four natural nucleobases that evolved on Earth.<ref>{{cite journal | vauthors = Warren M |title=Four new DNA letters double life's alphabet | journal = Nature |date=21 February 2019 | doi = 10.1038/d41586-019-00650-8 | pmid = 30809059 | volume=566 | issue = 7745 | page=436| doi-access = free | bibcode = 2019Natur.566..436W }}</ref><ref>{{cite journal| vauthors = Hoshika S, Leal NA, Kim MJ, Kim MS, Karalkar NB, Kim HJ, Bates AM, Watkins NE, SantaLucia HA, Meyer AJ, DasGupta S, Piccirilli JA, Ellington AD, SantaLucia J, Georgiadis MM, Benner SA | display-authors = 6 |title=Hachimoji DNA and RNA: A genetic system with eight building blocks (paywall)|journal=[[Science (journal)|Science]] |volume=363 |issue=6429 |pages=884–887 |date=22 February 2019 | doi = 10.1126/science.aat0971 | pmid = 30792304 | pmc=6413494 | bibcode=2019Sci...363..884H}}</ref> On the other hand, DNA is tightly related to [[RNA]] which does not only act as a transcript of DNA but also performs as molecular machines many tasks in cells. For this purpose it has to fold into a structure. It has been shown that to allow to create all possible structures at least four bases are required for the corresponding [[RNA]],<ref>{{cite journal | vauthors = Burghardt B, Hartmann AK | title = RNA secondary structure design | journal = Physical Review E | volume = 75 | issue = 2 | pages = 021920 | date = February 2007 | doi = 10.1103/PhysRevE.75.021920 | pmid = 17358380 | url = https://link.aps.org/doi/10.1103/PhysRevE.75.021920| arxiv = physics/0609135 | bibcode = 2007PhRvE..75b1920B | s2cid = 17574854 }}</ref> while a higher number is also possible but this would be against the natural [[principle of least effort]].