Chemical Evolution and the Origin of Life
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How did life begin on the early Earth? We know that life today is driven by the universal laws of chemistry and physics. By applying these laws over the past ?fty years, en- mous progress has been made in understanding the molecular mechanisms that are the foundations of the living state. For instance, just a decade ago, the ?rst human genome was published, all three billion base pairs. Using X-ray diffraction data from crystals, we can see how an enzyme molecule or a photosynthetic reaction center steps through its catalytic function. We can even visualize a ribosome, central to all life, translate - netic information into a protein. And we are just beginning to understand how molecular interactions regulate thousands of simultaneous reactions that continuously occur even in the simplest forms of life. New words have appeared that give a sense of this wealth of knowledge: The genome, the proteome, the metabolome, the interactome. But we can’t be too smug. We must avoid the mistake of the physicist who, as the twentieth century began, stated con?dently that we knew all there was to know about physics, that science just needed to clean up a few dusty corners. Then came relativity, quantum theory, the Big Bang, and now dark matter, dark energy and string theory. Similarly in the life sciences, the more we learn, the better we understand how little we really know. There remains a vast landscape to explore, with great questions remaining.
Bromm V (2001) Scientific American, December Luminet J-P, Weeks JR, Riazuelo A, Lehoucq R, Uzan J-P (2003) Nature 425:593 Luu JX, Jewitt DL (1996) Scientific American, May Macdougall JD (1996) A Short History of Planet Earth. John Wiley and Sons, Inc., New York Maci´a E, Hern´andez MV, Or´o J (1997) Orig Life Evol Biosphere 27:459 Maci´a E (2005) Chem Soc Rev 34:691 Mason SF (1992) Chemical Evolution. Clarendon Press, Oxford Miller SL (1953) Science 117:528 Mojzsis SJ, Harrison TM, Pitgeon RT
the other similarly sized Jovian moons (which are closer to the sun, but have an escape 54 3 From the Planets to Interstellar Matter velocity of the same magnitude)? One explanation is that the orbit of the Jovian moons lies within the sphere of influence of Jupiter’s strong magnetosphere, whereas Titan is only slightly affected by the magnetosphere of Saturn. Its greater distance from the sun could also be important, since lower temperatures favour the incorporation of volatile gases into
sky is something which fascinates many people; the comet’s long tail of luminescent material moving rapidly in the dark night sky has been the subject of much speculation across the centuries. Aristotle mentions comets, which he considers to consist of substances which evaporate from the Earth’s surface and ignite when they reach great heights. In the Middle Ages, comets induced fear and trepidation: their appearance was considered to herald catastrophic events to come. Tycho Brahe is seen as the
aerosol led to the synthesis of several amino acids (in particular alanine, glycine and β-alanine), but also to that of adenine and other purines; in addition, some hydroxyl acids (e.g., glycolic acid) were formed. Control experiments in the absence of aerosol showed either much lower yields or even values below the limits of measurement (Ruiz-Bermejo et al., 2007). The discovery of hydrothermal vents on the ocean floor has led some biogenesis researchers to turn their attention to the
hydrolysis. The ninhydrin method indicates that the yields are around 50% (B¨ohler et al., 1996) 5.4 Simulation Experiments 137 In the same institute, experiments involving evaporation cycles were carried out, as these may have occurred periodically on Earth in the neighbourhood of volcanoes (Saetia et al., 1993); the previously described “salt-induced peptide synthesis” (SIPS) was used. Apart from the amino acids already mentioned, glutamic acid, aspartic acid, valine and proline were also