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On the origin of metabolic pathwaysThe heterotrophic theory of the origin of life is the only proposal available with experimental support. This comes from the ease of prebiotic synthesis under strongly reducing conditions. The prebiotic synthesis of organic compounds by reduction of CO(2) to monomers used by the first organisms would also be considered an heterotrophic origin. Autotrophy means that the first organisms biosynthesized their cell constituents as well as assembling them. Prebiotic synthetic pathways are all different from the biosynthetic pathways of the last common ancestor (LCA). The steps leading to the origin of the metabolic pathways are closer to prebiotic chemistry than to those in the LCA. There may have been different biosynthetic routes between the prebiotic and the LCAs that played an early role in metabolism but have disappeared from extant organisms. The semienzymatic theory of the origin of metabolism proposed here is similar to the Horowitz hypothesis but includes the use of compounds leaking from preexisting pathways as well as prebiotic compounds from the environment.
Document ID
20040141828
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Lazcano, A.
(Universidad Nacional Autonoma de Mexico, Cd. Universitaria Apartado Postal 70-407, 04510 Mexico D.F., Mexico)
Miller, S. L.
Bada, J. L.
Date Acquired
August 22, 2013
Publication Date
October 1, 1999
Publication Information
Publication: Journal of molecular evolution
Volume: 49
Issue: 4
ISSN: 0022-2844
Subject Category
Exobiology
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Exobiology
Review, Tutorial
Non-NASA Center
Review

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