Editing DNA (section)

=== Sense and antisense ===
{{further|Sense (molecular biology)}}
{{redirect|Sense and antisense|the TV episode|Sense and Antisense (Millennium)}}
A [[DNA sequencing|DNA sequence]] is called a "sense" sequence if it is the same as that of a [[messenger RNA]] copy that is translated into protein.<ref>[http://www.chem.qmul.ac.uk/iubmb/newsletter/misc/DNA.html Designation of the two strands of DNA] {{Webarchive|url=https://web.archive.org/web/20080424015915/http://www.chem.qmul.ac.uk/iubmb/newsletter/misc/DNA.html |date=24 April 2008 }} JCBN/NC-IUB Newsletter 1989. Retrieved 7 May 2008</ref> The sequence on the opposite strand is called the "antisense" sequence. Both sense and antisense sequences can exist on different parts of the same strand of DNA (i.e. both strands can contain both sense and antisense sequences). In both prokaryotes and eukaryotes, antisense RNA sequences are produced, but the functions of these RNAs are not entirely clear.<ref>{{cite journal | vauthors = Hüttenhofer A, Schattner P, Polacek N | title = Non-coding RNAs: hope or hype? | journal = Trends in Genetics | volume = 21 | issue = 5 | pages = 289–97 | date = May 2005 | pmid = 15851066 | doi = 10.1016/j.tig.2005.03.007 }}</ref> One proposal is that antisense RNAs are involved in regulating [[gene expression]] through RNA-RNA base pairing.<ref>{{cite journal | vauthors = Munroe SH | title = Diversity of antisense regulation in eukaryotes: multiple mechanisms, emerging patterns | journal = Journal of Cellular Biochemistry | volume = 93 | issue = 4 | pages = 664–71 | date = November 2004 | pmid = 15389973 | doi = 10.1002/jcb.20252 | s2cid = 23748148 }}</ref>

A few DNA sequences in prokaryotes and eukaryotes, and more in [[plasmid]]s and [[virus]]es, blur the distinction between sense and antisense strands by having [[overlapping gene]]s.<ref>{{cite journal | vauthors = Makalowska I, Lin CF, Makalowski W | title = Overlapping genes in vertebrate genomes | journal = Computational Biology and Chemistry | volume = 29 | issue = 1 | pages = 1–12 | date = February 2005 | pmid = 15680581 | doi = 10.1016/j.compbiolchem.2004.12.006 }}</ref> In these cases, some DNA sequences do double duty, encoding one protein when read along one strand, and a second protein when read in the opposite direction along the other strand. In [[bacteria]], this overlap may be involved in the regulation of gene transcription,<ref>{{cite journal | vauthors = Johnson ZI, Chisholm SW | title = Properties of overlapping genes are conserved across microbial genomes | journal = Genome Research | volume = 14 | issue = 11 | pages = 2268–72 | date = November 2004 | pmid = 15520290 | pmc = 525685 | doi = 10.1101/gr.2433104 }}</ref> while in viruses, overlapping genes increase the amount of information that can be encoded within the small viral genome.<ref>{{cite journal | vauthors = Lamb RA, Horvath CM | title = Diversity of coding strategies in influenza viruses | journal = Trends in Genetics | volume = 7 | issue = 8 | pages = 261–66 | date = August 1991 | pmid = 1771674 | doi = 10.1016/0168-9525(91)90326-L | pmc = 7173306 }}</ref>