Download Figure 2.16 Synthesis of Prebiotic Molecules in an Experimental

Figure 2.16 Synthesis of Prebiotic Molecules in an Experimental Atmosphere
Stanley Miller and Nobel laureate Harold Urey conducted an experiment in which they
simulated hypothetical conditions thought to be present on early Earth, and then tested for the
presence of organic compounds. A number of complex molecules, including amino acids,
pyrimidines, and purines, were detected in the system. The generation of these molecules was
consistent with the theory of a chemical origin of life on Earth. While the results of this
experiment have been reinterpreted and refined over the years, it is considered to be a classic
experiment and represents the first foray into experimental research focusing on the origin of
life. It is important to note that in order for the Miller–Urey experiment to work, a reducing
atmosphere is required. In such an atmosphere, hydrogen is present, but oxygen is absent.
Paradoxically, while oxygen is absolutely essential for multicellular, advanced life, it inhibits
prebiotic synthesis. Thus, if oxygen were present in the Miller–Urey experiment, the formation
of organic compounds would be impossible, and oxygen would destroy any organic material
present. Accordingly, scientists have proposed that early Earth had no elemental oxygen, but
that it developed an oxidizing atmosphere as primitive life produced oxygen through
photosynthesis. Other geological and paleontological evidence, however, suggests that an
oxygen-based atmosphere existed on early Earth, and therefore a number of questions
regarding the origin of life remain unanswered.
Original Papers
Miller, S. L. 1953. A production of amino acids under possible primitive earth conditions.
Science 117: 528–529.
http://www.jstor.org/stable/1680569
http://www.physics.nmt.edu/~mce/Miller_1953.pdf
Miller, S. L., and H. C. Urey. 1959. Organic compound synthesis on the primitive earth.
Science 130: 245–251.
http://www.jstor.org/stable/1757918
http://www.physics.nmt.edu/~mce/Miller_Urey_1959.pdf
Links
Analysis of Miller’s experiments decades later:
Johnson A. P., H. J. Cleaves, J. P. Dworkin, D. P. Glavin, A. Lazcano, and J. L. Bada. 2008. The
Miller volcanic spark discharge experiment. Science 322: 404.
http://www.sciencemag.org/cgi/reprint/322/5900/404
http://www.sciencedaily.com/releases/2008/10/081016141411.htm
University of California, San Diego Television: Miller–Urey Experiment
http://www.ucsd.tv/miller-urey/
Access Excellence: From Primordial Soup to the Prebiotic Beach
http://www.accessexcellence.org/WN/NM/miller.html
Science Magazine: Perceptions of Science: Prebiotic Soup—Revisiting the Miller Experiment
http://www.sciencemag.org/cgi/content/full/300/5620/745
Kimball’s Biology Pages: The Origin of Life
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AbioticSynthesis.html
Astrobiology Magazine: Reflections From a Warm Little Pond
http://www.astrobio.net/exclusive/5/reflections-from-a-warm-little-pond