Editing DNA (section)

=== Alternative DNA chemistry ===
{{further|hypothetical types of biochemistry}}
For many years, [[Astrobiology|exobiologists]] have proposed the existence of a [[shadow biosphere]], a postulated microbial [[biosphere]] of Earth that uses radically different biochemical and molecular processes than currently known life. One of the proposals was the existence of lifeforms that use [[Arsenic DNA|arsenic instead of phosphorus in DNA]]. A report in 2010 of the possibility in the [[bacterium]] [[GFAJ-1]] was announced,<ref name='arsenic extremophile'>{{cite news | vauthors = Palmer J |title=Arsenic-loving bacteria may help in hunt for alien life |date=2 December 2010 |url=https://www.bbc.co.uk/news/science-environment-11886943 |work=BBC News |access-date=2 December 2010 |url-status=live |archive-url=https://web.archive.org/web/20101203045804/http://www.bbc.co.uk/news/science-environment-11886943 |archive-date=3 December 2010 }}</ref><ref name="Space">{{cite news | vauthors = Bortman H |title=Arsenic-Eating Bacteria Opens New Possibilities for Alien Life |date=2 December 2010 |url=http://www.space.com/scienceastronomy/arsenic-bacteria-alien-life-101202.html |website=Space.com |access-date=2 December 2010 |url-status=live |archive-url=https://web.archive.org/web/20101204235915/http://www.space.com/scienceastronomy/arsenic-bacteria-alien-life-101202.html |archive-date=4 December 2010 }}</ref> though the research was disputed,<ref name="Space" /><ref>{{cite journal | vauthors = Katsnelson A |title=Arsenic-eating microbe may redefine chemistry of life |date=2 December 2010 |url=http://www.nature.com/news/2010/101202/full/news.2010.645.html |journal=Nature News |doi=10.1038/news.2010.645 |url-status=live |archive-url=https://web.archive.org/web/20120212155007/http://www.nature.com/news/2010/101202/full/news.2010.645.html |archive-date=12 February 2012 }}</ref> and evidence suggests the bacterium actively prevents the incorporation of arsenic into the DNA backbone and other biomolecules.<ref name="Nature">{{cite journal | vauthors = Cressey D |s2cid=87341731 |title='Arsenic-life' Bacterium Prefers Phosphorus after all |date=3 October 2012 |journal=Nature News |doi=10.1038/nature.2012.11520}}</ref>