Editing Semiconservative replication (section)

== Discovery ==

[[File:Meselson-stahl_experiment_diagram_en.svg|alt=|thumb|Meselson-Stahl experiment using isotopes to discover semiconservative replication.]]

Multiple experiments were conducted to determine how DNA replicates. The semiconservative model was anticipated by [[Nikolai Koltsov]] and later supported by the [[Meselson–Stahl experiment]],<ref name="Meselson_1958" /><ref>{{cite book|title=Phage and the Origins of Molecular Biology|vauthors=Meselson M, Stahl FW|date=2007|publisher=Cold Spring Harbor Laboratory Press|isbn=978-0-87969-800-3|veditors=Cairns J, Stent GS, Watson JD|location=Cold Spring Harbor|chapter=Demonstration of the semiconservative mode of DNA duplication.}}</ref> which confirmed that DNA replicated semi-conservatively by conducting an experiment using two [[isotopes]]: [[Nitrogen 15|nitrogen-15]] ({{SimpleNuclide|Nitrogen|15}}) and [[Nitrogen 14|nitrogen-14]] ({{SimpleNuclide|Nitrogen|}}). When {{SimpleNuclide|Nitrogen|}} was added to the heavy {{SimpleNuclide|Nitrogen|15}}-{{SimpleNuclide|Nitrogen|15}} DNA, a hybrid of {{SimpleNuclide|Nitrogen|15}}-{{SimpleNuclide|Nitrogen|}} was seen in the first generation. After the second generation, the hybrid remained, but light DNA ({{SimpleNuclide|Nitrogen|}}-{{SimpleNuclide|Nitrogen|}}) was seen as well. This indicated that DNA replicated semi-conservatively. This mode of DNA replication allowed for each daughter strand to remain associated with its template strand.<ref>{{cite journal | vauthors = Hanawalt PC | title = Density matters: the semiconservative replication of DNA | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 101 | issue = 52 | pages = 17889–94 | date = December 2004 | pmid = 15608066 | doi = 10.1073/pnas.0407539101 | doi-access = free | pmc = 539797 }}</ref>