We don't know how life began but one of the more fanciful hypotheses is that it began in a primordial soup of organic molecules supplied by meteors, comets, and violent lightening storms. The idea is that the ocean was full of glucose, amino acids, and nucleotides. Glucose and similar carbohydrates supplied the energy for life. Amino acids spontaneously came together to form proteins. Nucleic acids arose by stringing together pre-existing nucleotides or nucleosides.
In the most extreme version, the ocean itself was the primordial soup and concentrations of organic molecules were sufficient to drive the formation of life. A simple back-of-the envelope calculation indicates that the concentration of typical amino acids would have been about 0.1 nM (10-10 M) [Can watery asteroids explain why life is 'left-handed'?]. This is an unlikely scenario [More Prebiotic Soup Nonsense]. You won't get spontaneous formation of polymers in water at that concentration.
Was the Origin of Life a Lucky Accident?] [Metabolism First and the Origin of Life]. (Bill Martin is one of the leading proponents of "Metabolism First." He can be a very persuasive guy!)
In this scenario life arose in restricted environments around thermal vents. The triggering force was the presence of natural proton gradients that could drive spontaneous chemical reactions. This energy source resulted in the formation of simple compounds like glycine, acetate, glcerol. These simple compounds serve as substrates for the synthesis of more complex molecules.
"Metabolism First" postulates that "life" bootstrapped its way up from very simple molecules rather than arising in a primordial soup where those molecules already existed. One of the great advantages of "Metabolism First" is that is offers a reasonable explanation for the preferred chirality of amino acids and sugars. The preference for L-amino acids, for example, may have arisen naturally from primitive catalysis reactions where the original product just happened to be L-alanine or some other simple amino acid [Amino Acids and the Racemization "Problem"] [Nicholas Wade on the Origin of Life ].
NASA Confusion About the Origin of Life].
NASA has done it again: NASA and university researchers find a clue to how life turned left.
Researchers analyzing meteorite fragments that fell on a frozen lake in Canada have developed an explanation for the origin of life's handedness – why living things only use molecules with specific orientations. The work also gave the strongest evidence to date that liquid water inside an asteroid leads to a strong preference of left-handed over right-handed forms of some common protein amino acids in meteorites. The result makes the search for extraterrestrial life more challenging.The problem with this work is not that it's bad science. It's that it automatically assumes a particular view of the origin of life and doesn't take into account the idea that the results may be irrelevant. Even worse, the results consistently fail to provide a reasonable explanation for the amino acid chirality "problem" but it never seems to occur to the researchers that their hypothesis has been falsified. Maybe it's time to look for another explanation?
"Our analysis of the amino acids in meteorite fragments from Tagish Lake gave us one possible explanation for why all known life uses only left-handed versions of amino acids to build proteins," said Dr. Daniel Glavin of NASA's Goddard Space Flight Center in Greenbelt, Md. Glavin is lead author of a paper on this research to be published in the journal Meteoritics and Planetary Science.