12 The Astrobiological Dimension
Water is constantly looked out for in astrobiological explorations.10 It is important for a number of reasons. First, water has attractive physical properties. Its anomalous expansion at the freezing point and its high specific heat make it more difficult for a body of water to become frozen solid throughout its entire volume. With a high dielectric constant it is an excellent solvent for charged ions and hydrogen bond-ing.11 Without ions and hydrogen bonds, energy generation through proton...
iiPreventing Idle Ribosomes in the Presence of an Excess of EFG
We already mentioned that four proteins participate in translation during the elongation phase. Two ofthem, EF-Tu and EF-G, are components of the central activity of the ribosome, the elongation cycle, where in a cycle of reactions the nascent chain is extended by one amino acid aa . EF-Tu brings the aa in the form of aa-tRNA to the decoding centre of the ribosome and EF-G translocates the tRNAs on the ribosome by one codon length reviewed in ref. 20 . These two factors, together with EF-Ts and...
From Prebiotic Chemistry to Life on Europa
With the possible presence of liquid water in its not too far subsurface, Europa is a target of great interest for the astrobiologist community. The other conditions availability of organic matter and energy necessary for the emergence of Life may have also been present on in Europa in its early history. As it very likely occurred on Earth, many organics may have been imported to Europa from meteorites. Furthermore, Galilean satellites may be largely made of material from carbonaceous...
Specific References
6. Fairley J. The spontaneous generation controversy from Descartes to Oparin. John Hopkins Univ Press 1977. 7. Raulin-Cerceau F. Historical review of the origin of life and astrobiology. In Seckbach J, ed. Origins, Genesis, Evolution and Diversity of Life. Kluwer Academic Publishers, 2004 17-33. 8. Oparin AI translated by Morgulis S . The Origin of Life. MacMillan 1938 109-195. 9. Bada JL, Lazcano A. Prebiotic soup revisiting the Miller experiment. Science 2003 300 745-746. 10. Franck S, von...
14 Heterotrophic Origin
i Heterotrophy First vs. Autotrophy First There are two schools of thought on whether the first cell was a heterotroph feeding on organic compounds available from environmental sources, or an autotroph using only CO2 and one-carbon compounds from the environment to synthesize all other organic compounds in-house Fig. 1.3 . Prebiotic evolution began with membranes, replicators and metabolites and proceeded to the Last Universal Common Ancestor, or LUCA, from which all extant life descended. Its...
15 Defining Moment of Life
If one is to name the longest running riddle, this one must rank high. All humans pass through life once, cherish it and are always fascinated by it. This fascination is precious common ground for humanity, cutting across all barriers of time, geography and language. For prebiotic evolution, solving the riddle is sheer necessity, for it is impossible to know when prebiotic ends and biotic begins without knowing what biotic means. Some definitions of life go back many decades 63 FG Hopkins in...