Life Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! === Chemical elements === All life forms require certain core [[chemical element]]s for their [[biochemistry|biochemical]] functioning. These include [[carbon]], [[hydrogen]], [[nitrogen]], [[oxygen]], [[phosphorus]], and [[sulfur]]βthe elemental [[nutrient|macronutrients]] for all organisms.<ref name=wsj20101203>{{cite news |first1=Robert Lee |last1=Hotz |title=New link in chain of life |work=[[The Wall Street Journal]] |date=3 December 2010 |url=https://www.wsj.com/articles/SB10001424052748703377504575650840897300342?mod=ITP_pageone_1#printMode |quote=Until now, however, they were all thought to share the same biochemistry, based on the Big Six, to build proteins, fats and DNA. |url-status=live |archive-url=https://web.archive.org/web/20170817163835/https://www.wsj.com/articles/SB10001424052748703377504575650840897300342?mod=ITP_pageone_1#printMode |archive-date=17 August 2017 }}</ref> Together these make up [[nucleic acid]]s, proteins and [[lipid]]s, the bulk of living matter. Five of these six elements comprise the chemical components of DNA, the exception being sulfur. The latter is a component of the amino acids [[cysteine]] and [[methionine]]. The most abundant of these elements in organisms is carbon, which has the desirable attribute of forming multiple, stable [[covalent bond]]s. This allows carbon-based (organic) molecules to form the immense variety of chemical arrangements described in [[organic chemistry]].<ref name="Lipkus Yuan Lucas Funk 2008 pp. 4443β4451">{{cite journal | last1=Lipkus | first1=Alan H. | last2=Yuan | first2=Qiong | last3=Lucas | first3=Karen A. | last4=Funk | first4=Susan A. | last5=Bartelt | first5=William F. | last6=Schenck | first6=Roger J. | last7=Trippe | first7=Anthony J.| title=Structural Diversity of Organic Chemistry. A Scaffold Analysis of the CAS Registry | journal=The Journal of Organic Chemistry | publisher=American Chemical Society (ACS) | volume=73 | issue=12 |year=2008 | doi=10.1021/jo8001276 | pages=4443β4451| pmid=18505297 | doi-access=free }}</ref> Alternative [[hypothetical types of biochemistry]] have been proposed that eliminate one or more of these elements, swap out an element for one not on the list, or change required [[Chirality (chemistry)|chiralities]] or other chemical properties.<ref>{{cite book |author1=Committee on the Limits of Organic Life in Planetary Systems |author2=Committee on the Origins and Evolution of Life |author3=National Research Council |date=2007 |publisher=National Academy of Sciences |title=The Limits of Organic Life in Planetary Systems |isbn=978-0-309-66906-1 |url=http://www.nap.edu/catalog.php?record_id=11919 |access-date=3 June 2012 |url-status=live |archive-url=https://web.archive.org/web/20120510213123/http://www.nap.edu/catalog.php?record_id=11919 |archive-date=10 May 2012 }}</ref><ref>{{cite journal |first1=Steven A. |last1=Benner |first2=Alonso |last2=Ricardo |first3=Matthew A. |last3=Carrigan |journal=Current Opinion in Chemical Biology |title=Is there a common chemical model for life in the universe? |volume=8 |issue=6 |date=December 2004 |pages=672β689 |doi=10.1016/j.cbpa.2004.10.003 |url=http://www.fossildna.com/articles/benner_commonmodelforlife.pdf |archive-url=https://web.archive.org/web/20121016220349/http://www.fossildna.com/articles/benner_commonmodelforlife.pdf |archive-date=16 October 2012 |url-status=dead |access-date=3 June 2012 |pmid=15556414}}</ref> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Christianpedia:Copyrights for details). Do not submit copyrighted work without permission! Cancel Editing help (opens in new window) Discuss this page