Primitive earth

Miller, S. L. (1953). A production of amino acids under possible primitive Earth conditions. Science 117, 528-529. 

In tracing the evolutionary development of iron ligands it is of interest to examine the machinery employed by organisms which carry out reactions on those substances believed to have been present on the primitive Earth. Specific substrates acted on by this group include, besides ferrous iron itself, hydrogen sulfide, hydrogen gas, methane and reduced nitrogen compounds. Species which perform photosynthesis may be presumed to have the capacity to synthesize protoporphyrin IX since this substance is an intermediate in chlorophyll biosynthesis (43). 

Then came the year 1953, and with it important events, both political and scientific in nature the death of Stalin and the determination of the structure of DNA in addition, a scientific article was published in Science by a previously unknown author, Stanley L. Miller. Its title was A Production of Amino Acids under Possible Primitive Earth Conditions (Miller, 1953). 

The wavelengths at which most of the components of a primitive Earth atmosphere absorb lie, with few exceptions, under 200 nm. The exceptions include ammonia (< 230 nm), hydrogen sulphide (<260 nm) and ozone (180-300 nm). However, ozone was probably present in the primeval atmosphere only in trace amounts, since free oxygen was only available in extremely low concentrations. The young Earth thus had no protective ozone layer, so short-wavelength UV irradiation could readily penetrate the atmosphere. 

The RNA world hypothesis caused prebiotic phosphate chemistry to become an attractive research area again unfortunately, no clear evidence for a realistic nucleotide synthesis under the simplified conditions of a primitive Earth has yet appeared. Important work on nucleoside phosphorylation has, however, been done. It is important to distinguish between ... 

The analysis of the laboratory ice experiments reveals a diverse array of bio-logical-looking molecules with the potential to seed life. Cometary collisions with planets could deliver these molecules to a primitive Earth or indeed to all planets within the solar system. The frequency of the collisions depends somewhat on the local star and the structure of the solar system forming around it. 

Ehrenfreund P., et al. (2003). Physics and chemistry of icy particles in the universe answers from microgravity. Planetary and Space Science 51 473-494 Emeline A. V. (2003). Abiogenesis and photo-stimulated heterogeneous reactions in the interstellar medium and on primitive Earth. Relevance to the genesis of life.. Journal of Photochemistry and Photobiology C 3 203. 

Ever since the beginning of life on primitive Earth, biopolymers and biomolecules have essentially comprised optically active constituents because of the natural selection of Z-amino acids and tZ-sugars. Although the origin of this biomolecular handedness is a long debated issue among biologists, chemists, physicists, and astronomers,1 5 it is accepted that our life is a consequence of the chemistry of homochiral biosubstances. Deoxyribonucleic acid (DNA) is a classic example of a chiral biopolymer. Its chirality is essentially characterized... 

Was Nature s selection of these stereochemical structures a random event, or was it the consequence of determinate processes Although the presence of amino adds and other organic molecules on primitive Earth has been attributed to both endogenous and exogenous sources, [5,6] the origin of the chiral bias of prebiotic molecules remains a fundamental mystery. A mystery perhaps even more central to the origin of life is the mechanism that brought into dominance and survival any putative small chiral molecular excess on early Earth. 

Once chirality is induced and amplified by some mechanism, the excess must first persist and then propagate in order to survive. A distinctive characteristic of homo-chiral protein and nucleic acid biopolymers is that they function within the enclosed environment of cells, which provide a membranous boundary structure that separates the intracellular components from the external environment. It has accordingly been postulated frequently that analogous but simpler enclosed environments must have been available and operative on the primitive Earth. 

The question as to the potential availability of the requisite amphiphilic precursors in the prebiotic environment has been addressed experimentally by Deamer and coworkers, [143,145] who looked into the uncontaminated Murchison chondrite for the presence of such amphiphilic constituents. Samples of the meteorite were extracted with chloroform-methanol and the extracts were fractionated by thin-layer chromatography, with the finding that some of the fractions afforded components that formed monomolecular films at air-water interfaces, and that were also able to self-assemble into membranous vesicles able to encapsulate polar solutes. These observations dearly demonstrated that amphiphiles plausibly available on the primitive Earth by meteoritic infall have the ability to self-assemble into the membranous vesides of minimum protocells. ... 

The enantioselective incorporation of these amino acids into the serine octamers represents an example of chiral transmission to elementary biomolecules and a possible way of chirality amplification on primitive earth. 

In his review, Miller (1998) recalls other compounds that have been synthesized under primitive Earth conditions, such as di- and tri-carboxylic acids, C2-C10 fatty acids, porphin, imidazoles, and he also mentions products that have not been... 

Amino acid synthesis from hydrogen cyanide under possible primitive Earth conditions. Nature, 190,442-3. 

Or6, J. and Kimball, A. P. (1961). Synthesis of purines under possible primitive Earth conditions. 1. Adenine from hydrogen cyanide. Arch. Biochem. Biophys., 94,... 

Rode, B. M., Son, H. L. and Suwannachot, Y. (1999). The combination of salt induced peptide formation reaction and clay catalysis a way to higher peptides under primitive earth conditions. Orig. Life. Evol. Biosph., 29, 273-86. 

Cloud PE (1968) Atmospheric and hydrospheric evolution on the primitive Earth. Science 160 729-736... 

The energy from the decay of radioactive elements was probably not an important energy source for the synthesis of organic compounds on the primitive earth since most of the ionization would have taken place in silicate rocks rather than in the reducing atmosphere. The shock wave energy from the impact of meteorites on the earth s atmosphere and sur-... 

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