Changes
Amino acid yield in spark discharge experiments depends critically on the pH of the aqueous phase since at lower pH, amino acid production is greatly reduced and hydroxy acids in greatly increased.<ref name="Bada2013" /> Hydrothermal vents have been proposed as an alternative prebiotic chemistry source but they face severe limitations and actual synthesis have never been demonstrated using plausible geochemical conditions.<ref name="Bada2013" />
===Requirements Chemical requirements for non-living chemicals to become livinglife===
Life requires multiple chemical processes to exist simultaneously in a microscopic space. According to leading water & life chemist Felix Franks<ref>Felix Franks. 2010. "2. Water and Life Friend or Foe?". In Harper, Charles (ed.). Water and Life: The Unique Properties of H2O. CRC Press. ISBN 9781439803561 page 13</ref>
* energetic and intermediary metabolism (glycolysis, proton motive force generation, pentose phosphate pathway, lipid metabolism, and biosynthesis of nucleotides
and cofactors)
* all 20 amino acids
==Chemical problems facing abiogenesis==
