The Origins of Life

Introduction: The odds of winning the US Powerball lottery are approximately Eighty Million to one (Lottery, 2005). Would you take these odds over the odds of a complex organic structure arising spontaneously on Earth? Given the fact that the odds of the latter happening are approximately one in 10¹³⁰, you might think your safest bet is the lottery. However, this extremely small chance of occurrence is made more plausible when we remember that the formation of complex organic structures would not have been completely random, but would in fact have followed chemical and physical laws (Hall and Hallgrimsson, 2008, p. 109). When we take this into account maybe our choice would be a little tougher after all.

Support: Cooper (2000) points out some of the basic circumstances which needed to be met in order for life to have formed on the prebiotic Earth. It would first have been necessary for amino acids, nucleic acids and fatty acids to form. Amino acids and nucleic acids would then need to be able to polymerize to form proteins and polynucleotides. The polynucleotides would then need a way to replicate and pass on their information. The fatty acids that were created would need to be able form spheres which would aggregate the various organic compounds and protect them from outside agents. Finally these fatty acid spheres would need a way to replicate. Though the processes discussed in this paper are simplified, they nonetheless give the idea that this entire progression is very possible.

It has been shown that amino acids can be formed when necessary molecules are subjected to prebiotic Earth conditions. It has also been commonly observed that some meteorites have contained amino acids, suggesting that the formation of amino acids in a prebiotic environment is far from impossible (Porter, 2008). Nucleic acids have also been shown to be able to form in the prebiotic environment (Aihara, 1988, pp. 2309-2312), as have fatty acids (Ferris, 2000).

Each of the above mentioned monomers is able to polymerize into polymers. There have been many different theories for the polymerization of amino acids into proteins, one of which requires the action of oligonucleotides (Walder et al., 1979, pp. 51-55). Kawamura (2001, pp. 239-240) showed that under certain conditions RNA would polymerize faster than it would decompose, a fact that had been debated. This would lead to the production of polynucleotides.

Given the enzymatic and self-replicating characteristics of RNA it would seem that it played the part of the original nucleotide on Earth (Hall and Hallgrimsson, 2008, p. 129). There has been much debate on the capabilities of self-replication of RNA. However, Cech (1986, p. 4360) gives an example where an RNA polymerase would be based on a molecule made up of RNA itself. This shows that RNA could have the ability to self-replicate.

When fatty acids are placed in an aqueous solution, they tend to form boundaries, pointing their hydrophilic heads towards the water and their hydrophobic tails towards the tails of other fatty acids. This can lead to the formation of small cell like structures often called micelles (Gauthier, 1994, pp. 204-205). These micelles are able to grow, and divide just as modern cells do (Hanczyc and Szostak, 2004, pp. 660-664).

Conclusion: Once these micelles have formed, they could easily have incorporated proteins, polynucleotides and other molecules essential to the creation of life. Once these molecules were in such close proximity and protected from many outside agents, reactions that would lead to further evolutionary advancements would become much more efficient and probable. This is the point where natural selection could take off. Those micelles that could develop the ability to more efficiently copy the genetic information held inside and then replicate themselves would produce more and more "offspring" and would be more likely to survive. This would eventually lead to the differentiation of cell function and the evolution of complex organisms. Literature Cited

Aihara, J. 1988. Prebiotic Synthesis Obeys the Rule of Topological Charge Stabilization. The Chemical Society of Japan 61(7): 2309-2312.

Cech, T. R. 1986. A model for the RNA-catalyzed replication of RNA. Proceedings of the National Academy of Sciences of the United States of America 83 (12): 4360-4363.

Cooper, G. M. 2000. The Origin and Evolution of Cells, 2000 http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=cooper.section.90 Accessed 11 Feb 2009

Ferris, J. P. 2000. Space Studies Board, 28 Dec 2000 http://www7.nationalacademies.org/ssb/nanopanel4ferris.html Accessed 11 Feb 2009

Gauthier, P. 1994. Origins: Speculations about the spontaneous generation of the first biotic structures. Bios 65 (4): 204-214.

Hall, B. K. and B. Hallgrimsson. 2008. Strickerberger's Evolution. 4th Edition. Jones and Bartlett Publishers, MA. 760 pp.

Hanczyc, M. M. and J.W. Szostak. 2004. Replicating vesicles as models of primitive cell growth and division. Current Opinion in Chemical Biology 8 (6): 660-664.

Kawamura, K. 2001. Comparison of the rates of prebiotic formationand hydrolysis of RNA under hydrothermal environments and its implications on the chemical evolution of RNA. Nucleic Acids Research Supplement 1: 239-240.

Lottery Odds @ the Lottery Site - Information on Internet, US, and World Lotteries, 2005 http://thelotterysite.com/lottery_odds.htm Accessed 9 Feb 2009

Porter, T. L. 2008. Synthesis of Polypeptides Under Simulated Prebiotic, 2008 http://www.physics.nau.edu/~porter/Peptides.htm Accessed 11 Feb 2009

Walder, J. A., R. Y. Walder, M. J. Heller, S. M. Freier, R. L. Letsinger, I. M. Klotz. 1979. Complementary carrier peptide synthesis: General strategy and implications for prebiotic origin of petide synthesis. Proceedings of the National Academy of Sciences of the United States of America 76 (1): 51-55.