Prebiological Significance

The results of our laboratory experiments on the action of UV radiation with different wavelengths (145-260 nm), high-energy particles, g-radiation and heat show that many kinds of open space energy could be effective in the chemical evolution of nucleic acid precursors and oligopeptides [18-20,22,23]. The abiogenic synthesis of nucleotides and dipeptides can proceed in open space conditions in the early stages of Solar System evolution. The results of experiments on board "BION-11" enable us to conclude, that 5'-nucleotides are predominantly formed by the action of the full spectrum of space energy sources on dry thin films of nucleoside plus inorganic phosphate. Other nucleotides also have been found in the investigated films.

Of course, an irradiation of a few hours in a laboratory or a week of spaceflight cannot reproduce billions of years of slow evolution on the surfaces of small bodies that will never be reproduced in the laboratory. However, they might shed light on the basic tendency of the course of the chemical evolution.

So, the organic compounds, which had been delivered on the primordial Earth would have had a very complex structure and reached the second stage of the chemical evolution — polymerization. The small bodies could have imported prebiotic, complex molecules such as nucleotides and olygopeptides, to early Earth, which have allowed the fast synthesis of all molecules thought to be necessary for the origin of life. As shown by Basiuk and Douda [25] the safe delivery of these compounds depends on such factors as size of the space body, nature and altitude of the heating and it's chemical composition, and may be very successful in some cases. The comets, carbonaceous chondrites and other primitive bodies of the Solar System including interplanetary and interstellar dust particles are responsible for essentially all carbon compounds and water currently present in our planet [25].

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