The Relevance of Inorganic Nonlinear Chemical Reactions for the Origin of Life Studies

Can we look at contemporary biology and couple this with chemical insight to propose some plausible mechanisms for the origin of life on the planet? In what follows, we examine some promising chemical reactions by which the building blocks for nucleic acids might have been created about a billion years after the Earth formed. This could have led to self-assembling systems that were based on an all-RNA metabolism, where RNA is both catalytic and informational. We consider the breadth of RNA enzymes presently existing in biology, and to what extent these might have covered a wider range of chemistry in the RNA world. Ultimately, the RNA world would probably have given way to protein-based life quite quickly, and the origins of peptidyl transferase activity are discussed below.

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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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