origin of life
Life’s Puzzling Origins The prebiotic soup theory has dominated the thinking about how life has emerged over the past century. However, the discovery of extraterrestrial amino acids in the Muchison meteorite in 1970 has widened the scope of this debate. Adding further complexity to the origin of life, there is a schism over whether proteins of living cells or the genetic information was a precursor to the other. These debates have raised key questions over which conditions most favored the emergence of life. The myriad of organic life on the Earth may be derived from a number of sources: oceanic based genetic synthesis, volcanic-oceanic based metabolic synthesis, and interplanetary meteorites. Limitations of physical and experimental evidence has left this debate in much flux, but scientific progress for each theory has created a sense of optimism heading into the future. The soup theory was first provided support by Stanley Miller in 1953, since then it has become the mainstream theory behind the origins of life. Miller demonstrated that biomolecules, such as amino acids, could be synthesized under simulated Earth-like conditions. The soup theory states that abiotic, monomeric organic compounds would have originally came about in early oceans. In these early oceans, monomers would have undergone polymerization to become larger and more complex; eventually developing enclosed membrane systems, nucleic acids, and proteins.1 As polymeric combinations increased in variety, they may have developed the ability to catalyze their own self-replication; marking the appearance of heredity, variation, and reproduction.2 This would mark the origin of life along the forces of evolution. By this, the soup theory suggests that organic RNA was the first organic compound from which life originated. Experimental models have been constructed that support threose-based RNA in an evolutionary sequence in the DNA/protein world.3 On the progress made in natural synthesis, Dr.
Cited: Bada JL, Lazcano A. Origin of life. Some like it hot, but not the first biomolecules. Science June 14, 2002; Vol. 296: pp. 1982-1983. (Secondary Source) This article traced the many theories regarding the origin of life, with particular focus on the soup theory. Their discussion further delved into the debate over whether metabolic or genetic/replication molecules were the first to form, with the “metabolist” theory putting forward the notion that metabolic life was first and was formed in elevated temperatures near the Ocean floor. However as the article notes, there are limitations to the evidence that supports this theory, but ultimately, the limited information that scientists have currently is a prime reason for a lack of a definitive origin of life answer. Huber C, Wächtershäuser G. July 31, 1998 Peptides by activation of amino acids with CO on (Ni,Fe)S surfaces: implications for the origin of life. Science Vol. 281, pp. 670–672. (Primary Source) The results from this paper regarded experiments modeling volcanic or hydrothermic settings amino acids indicated that peptides could be formed by the use of (Ni,Fe)S and CO with H2S at 100 degrees C under anaerobic conditions. The author of this paper indicates that these were relevant geothermic conditions and that the results support a thermophilic origin of life. This relates to the other articles as it is an attempt to provide evidence for the “metabolistic” theory of the origin of life. Wade, Nicholas. "New Glimpses of Life’s Puzzling Origins." The New York Times. The New York Times, 16 June 2009. Web. 12 Feb. 2013. (Press Source) This article talked about the various methodologies and theories regarding the origin of life, including terrestrial explanation theories regarding, chemical replicating systems, and prebiotic chemistry of ocean environments. The article showed optimism for terrestrial explanation of the origin of life due to surprising advances in recent years, including a series of discoveries about the cell-like structures that could have formed naturally from fatty chemicals that was present in primitive Earth. This article relates to the secondary article as they cover the same topics, furthermore this article directly relates to the primary source since it references and critiques Wachterhauser’s work and theory.