Space scenario of the origin of life: The problem of chiral purity

S. A. Anikin; V. A. Avetisov; V. I. Goldanskii

doi:10.1007/bf02422112

Revival of the concept of the cold prehistory of life

European Review ◽

10.1017/s106279870000048x ◽

1993 ◽

Vol 1 (2) ◽

pp. 137-147 ◽

Cited By ~ 1

Author(s):

Vitalii I. Goldanskii

Keyword(s):

Origin Of Life ◽

Mirror Symmetry ◽

Solid Phase ◽

Outer Space ◽

Enantiomeric Excess ◽

Quantum Limit ◽

Spontaneous Breaking ◽

Quasi Equilibrium ◽

Chiral Purity ◽

The Origin Of Life

The extra-terrestrial scenario of the origin of life suggested by Svante Arrhenius (1908) as the ‘panspermia’ hypothesis was revived by the discovery of a low-temperature quantum limit of a chemical reaction rate in 1973. Entropy factors play no role near absolute zero, and slow molecular tunnelling can lead to the exothermic formation of quite complex molecules. Interstellar grains or particles of cometary tails could serve as possible cold seeds of life, with acetic acid, urea and products of their polycondensation as quasi-equilibrium intermediates. Scenarios of the origin of life should consider the appearance of a typical feature of living species—chiral purity of their aminoacids and sugars. Very cold solid environment hinders tunnelling racemization under conditions typical for outer space. However, the decisive problem of the origin of chiral purity of the Earth's biosphere is the mechanism of the spontaneous breaking of mirror symmetry rather than the search for some ‘advantage factors’ which can promote gradual accumulation of enantiomeric excess. Extra-terrestrial (cold, solid phase) scenarios of the origin of life seem to be more promising from that point of view than terrestrial (warm) scenarios. In a scheme of five main stages of prebiological evolution some problems important for further investigation are briefly discussed.

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The Tempo and mode(S) of Prebiotic Evolution

International Astronomical Union Colloquium ◽

10.1017/s0252921100014937 ◽

1997 ◽

Vol 161 ◽

pp. 419-429 ◽

Cited By ~ 1

Author(s):

Antonio Lazcano

Keyword(s):

Origin Of Life ◽

Organic Compounds ◽

Biological Evolution ◽

Current Evidence ◽

Early Diversification ◽

Time Period ◽

The Galaxy ◽

History Of ◽

Widespread Phenomenon ◽

The Origin Of Life

AbstractDifferent current ideas on the origin of life are critically examined. Comparison of the now fashionable FeS/H2S pyrite-based autotrophic theory of the origin of life with the heterotrophic viewpoint suggest that the later is still the most fertile explanation for the emergence of life. However, the theory of chemical evolution and heterotrophic origins of life requires major updating, which should include the abandonment of the idea that the appearance of life was a slow process involving billions of years. Stability of organic compounds and the genetics of bacteria suggest that the origin and early diversification of life took place in a time period of the order of 10 million years. Current evidence suggest that the abiotic synthesis of organic compounds may be a widespread phenomenon in the Galaxy and may have a deterministic nature. However, the history of the biosphere does not exhibits any obvious trend towards greater complexity or «higher» forms of life. Therefore, the role of contingency in biological evolution should not be understimated in the discussions of the possibilities of life in the Universe.

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Photochemical Evolution of Interstellar/Precometary Organic Material

International Astronomical Union Colloquium ◽

10.1017/s0252921100014585 ◽

1997 ◽

Vol 161 ◽

pp. 23-47 ◽

Cited By ~ 11

Author(s):

Louis J. Allamandola ◽

Max P. Bernstein ◽

Scott A. Sandford

Keyword(s):

Origin Of Life ◽

Building Blocks ◽

Complex Species ◽

Infrared Observations ◽

Interstellar Ice ◽

Polycyclic Aromatic ◽

Ultraviolet Photolysis ◽

The Origin Of Life ◽

Simple Molecules ◽

Complex Organic

AbstractInfrared observations, combined with realistic laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the building blocks of comets. Since comets are thought to be a major source of the volatiles on the primative earth, their organic inventory is of central importance to questions concerning the origin of life. Ices in molecular clouds contain the very simple molecules H2O, CH3OH, CO, CO2, CH4, H2, and probably some NH3and H2CO, as well as more complex species including nitriles, ketones, and esters. The evidence for these, as well as carbonrich materials such as polycyclic aromatic hydrocarbons (PAHs), microdiamonds, and amorphous carbon is briefly reviewed. This is followed by a detailed summary of interstellar/precometary ice photochemical evolution based on laboratory studies of realistic polar ice analogs. Ultraviolet photolysis of these ices produces H2, H2CO, CO2, CO, CH4, HCO, and the moderately complex organic molecules: CH3CH2OH (ethanol), HC(= O)NH2(formamide), CH3C(= O)NH2(acetamide), R-CN (nitriles), and hexamethylenetetramine (HMT, C6H12N4), as well as more complex species including polyoxymethylene and related species (POMs), amides, and ketones. The ready formation of these organic species from simple starting mixtures, the ice chemistry that ensues when these ices are mildly warmed, plus the observation that the more complex refractory photoproducts show lipid-like behavior and readily self organize into droplets upon exposure to liquid water suggest that comets may have played an important role in the origin of life.

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