Editing Urea cycle (section)

{{short description|Set of biochemical reactions}}
The '''urea cycle''' (also known as the '''[[ornithine]] cycle''') is a cycle of [[Biochemistry|biochemical]] reactions that produces [[urea]] (NH<sub>2</sub>)<sub>2</sub>CO from [[ammonia]] (NH<sub>3</sub>). Animals that use this cycle, mainly amphibians and mammals, are called [[ureotelic]].

The urea cycle converts highly toxic ammonia to urea for excretion.<ref name=":0">{{Cite book|title=Lehninger Principles of Biochemistry|last=Cox |first=Michael|date=2013-01-01|publisher=Freeman|isbn=9781429234146|oclc=901647690}}</ref> This cycle was the first metabolic cycle to be discovered by [[Hans Adolf Krebs|Hans Krebs]] and [[Kurt Henseleit]] in 1932,<ref name="Krebs1932a">{{cite journal|last1=Krebs|first1=Hans Adolf|author-link1=Hans Krebs (biochemist)|last2=Henseleit|first2=Kurt|author-link2=Kurt Henseleit|title=Untersuchungen über die Harnstoffbildung im Tierkörper|journal=Klinische Wochenschrift|volume=11|number=18|pages=757–759|doi=10.1007/bf01757657|year=1932}}</ref><ref name="Krebs1932b">{{cite journal|last1=Krebs|first1=Hans Adolf|author-link1=Hans Krebs (biochemist)|last2=Henseleit|first2=Kurt|author-link2=Kurt Henseleit|title=Untersuchungen über die Harnstoffbildung im Tierkörper. II|journal=Klinische Wochenschrift|volume=11|number=27|pages=1137–1139|doi=10.1007/BF01758220|year=1932}}</ref><ref name="Krebs1932c">{{cite journal|last1=Krebs|first1=Hans Adolf|author-link1=Hans Krebs (biochemist)|last2=Henseleit|first2=Kurt|author-link2=Kurt Henseleit|title=Untersuchungen über die Harnstoffbildung im Tierkörper|journal=Hoppe-Seyler's Zeitschrift für physiologische Chemie|volume=210|number=1–2|pages=33–66|doi=10.1515/bchm2.1932.210.1-2.33|year=1932}}</ref> five years before the discovery of the [[TCA cycle]]. The urea cycle was described in more detail later on by Ratner and Cohen. The urea cycle takes place primarily in the [[liver]] and, to a lesser extent, in the [[kidney]]s.