Editing Amino acid (section)

===Primordial synthesis===
The formation of amino acids and peptides is assumed to have preceded and perhaps induced the [[abiogenesis|emergence of life on earth]]. Amino acids can form from simple precursors under various conditions.<ref name="10.1016/j.gsf.2017.07.007"/> Surface-based chemical metabolism of amino acids and very small compounds may have led to the build-up of amino acids, coenzymes and phosphate-based small carbon molecules.<ref>{{cite journal | vauthors = Danchin A | title = From chemical metabolism to life: the origin of the genetic coding process | journal = Beilstein Journal of Organic Chemistry | volume = 13 | issue = 1 | pages = 1119–1135 | date = 12 June 2017 | pmid = 28684991 | pmc = 5480338 | doi = 10.3762/bjoc.13.111 }}</ref>{{additional citation needed|date=September 2022}} Amino acids and similar building blocks could have been elaborated into proto-[[peptide]]s, with peptides being considered key players in the origin of life.<ref name="10.1021/acs.chemrev.9b00664">{{cite journal | vauthors = Frenkel-Pinter M, Samanta M, Ashkenasy G, Leman LJ | title = Prebiotic Peptides: Molecular Hubs in the Origin of Life | journal = Chemical Reviews | volume = 120 | issue = 11 | pages = 4707–4765 | date = June 2020 | pmid = 32101414 | doi = 10.1021/acs.chemrev.9b00664 | s2cid = 211536416 | bibcode = 2020ChRv..120.4707F }}</ref>

[[File:Strecker amino acid synthesis scheme.svg|class=skin-invert-image|thumb|upright=1.75 |right|The Strecker amino acid synthesis|alt=For the steps in the reaction, see the text.]]
In the famous [[Urey-Miller experiment]], the passage of an electric arc through a mixture of methane, hydrogen, and ammonia produces a large number of amino acids. Since then, scientists have discovered a range of ways and components by which the potentially prebiotic formation and chemical evolution of peptides may have occurred, such as condensing agents, the design of self-replicating peptides and a number of non-enzymatic mechanisms by which amino acids could have emerged and elaborated into peptides.<ref name="10.1021/acs.chemrev.9b00664"/> Several hypotheses invoke the [[Strecker synthesis]] whereby hydrogen cyanide, simple aldehydes, ammonia, and water produce amino acids.<ref name="10.1016/j.gsf.2017.07.007">{{cite journal |doi=10.1016/j.gsf.2017.07.007|title=Origins of building blocks of life: A review |year=2018 | vauthors = Kitadai N, Maruyama S |journal=Geoscience Frontiers |volume=9 |issue=4 |pages=1117–1153 |bibcode=2018GeoFr...9.1117K |s2cid=102659869 |doi-access=free }}</ref>

According to a review, amino acids, and even peptides, "turn up fairly regularly in the [[primordial soup|various experimental broths]] that have been allowed to be cooked from simple chemicals. This is because [[nucleotide]]s are far more difficult to synthesize chemically than amino acids." For a chronological order, it suggests that there must have been a 'protein world' or at least a 'polypeptide world', possibly later followed by the '[[RNA world]]' and the '[[DNA world]]'.<ref>{{cite journal | vauthors = Milner-White EJ | title = Protein three-dimensional structures at the origin of life | journal = Interface Focus | volume = 9 | issue = 6 | pages = 20190057 | date = December 2019 | pmid = 31641431 | pmc = 6802138 | doi = 10.1098/rsfs.2019.0057 }}</ref> [[Codon]]–amino acids mappings may be the [[biology|biological]] information system at the primordial origin of life on Earth.<ref>{{cite journal | vauthors = Chatterjee S, Yadav S | title = The Coevolution of Biomolecules and Prebiotic Information Systems in the Origin of Life: A Visualization Model for Assembling the First Gene | journal = Life | volume = 12 | issue = 6 | pages = 834 | date = June 2022 | pmid = 35743865 | pmc = 9225589 | doi = 10.3390/life12060834 | doi-access = free | bibcode = 2022Life...12..834C }}</ref> While amino acids and consequently simple peptides must have formed under different experimentally probed geochemical scenarios, the transition from an abiotic world to the first life forms is to a large extent still unresolved.<ref>{{cite journal | vauthors = Kirschning A | title = The coenzyme/protein pair and the molecular evolution of life | journal = Natural Product Reports | volume = 38 | issue = 5 | pages = 993–1010 | date = May 2021 | pmid = 33206101 | doi = 10.1039/D0NP00037J | s2cid = 227037164 | doi-access = free }}</ref>