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The Limits of Organic Life in Planetary Systems
FIGURE 2.14 A generic RNA molecule. The bonds shown in red are thermodynamically unstable with respect to hydrolysis in water. Each of these bonds represents a problem for prebiotic synthesis, as well as the maintenance of the genetic information in RNA in modern life. Today, the aggressive reactivity of water with respect to molecules like RNA and DNA is mitigated by sophisticated repair systems. It is difficult to imagine such complex repair systems having been present at the dawn of life. This conundrum underlies the most significant paradox in the structure of genetic matter with respect to the origin of life. On the one hand, the repeating charge in the backbone suggests that the molecule worked in a hydrophilic solvent such as water. On the other hand, the abundance of easily hydrolyzable bonds suggests that RNA could not have been easily assembled in water.
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