What is Selectable marker?
A '''selectable marker''' is a reporter [[gene]] introduced into a [[cell (biology)|cell]] along with a [[DNA insert|gene insert]]. What this means is, the experimenter can tell the right gene is in the cell because the marker can be seen or detected. Most often, this is used for [[bacterium|bacteria]] or for cells in [[cell culture|culture]]. Selectable markers show the success of a [[transfection]] or other procedure meant to introduce foreign [[DNA]] into a cell. It is a technique in [[gene targeting]] and [[gene knockout]].<ref>{{Cite web |url=http://www.cellmigration.org/resource/komouse/images/mousefig2.png |title=Callmigration.org: Gene targeting |access-date=2008-10-25 |archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303194513/http://www.cellmigration.org/resource/komouse/images/mousefig2.png |url-status=dead }}</ref> Selectable markers are often [[antibiotic resistance]] genes; bacteria that have been subjected to a procedure to introduce foreign DNA are grown on a medium containing an antibiotic. The antibiotic knocks out cells which do not have the resistant marker. Those bacterial [[colony (biology)|colonies]] that can grow have successfully taken up and [[gene expression|expressed]] the introduced genetic material. An alternative to a selectable marker is a '''screenable marker''', which allows the researcher to distinguish between wanted and unwanted cells. Examples of selectable markers include: *[[Beta-lactamase]] which confers [[ampicillin]] resistance to bacterial hosts. *Neo gene from Tn5, which confers antibiotic resistance to [[kanamycin]] in bacteria and to [[geneticin]] in [[eukaryote]] cells. *Mutant FabI gene (mFabI) from ''E. coli'' genome, which confers triclosan resistance to the host.<ref>{{cite journal|title=A novel selection marker for efficient DNA cloning and recombineering in'' E. coli''|journal=PLOS ONE|date= 2013 |volume=8|issue=2|pages=e57075|doi=10.1371/journal.pone.0057075|pmid=23437314|doi-access=free|last1=Jang|first1=Chuan-Wei|last2=Magnuson|fi