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Sugar phosphate backbone ester8/8/2023 ![]() Sugar, phosphate, and bases of RNA have been refined by evolution. Of Darwinian evolution (selected for the hydrolytic stability it provides this long-lived biopolymer), so, too, might the Just as the deoxyribose sugar of DNA was likely the product Polymer (or proto-RNA) was used by the earliest forms of life. In support of this model, Sutherland presents in his article current progress toward discovering possibleĬhemical pathways for the prebiotic synthesis of RNA mononucleotides, as well as methods for their protein-free polymerizationĪ second school of thought, discussed in this article, considers RNA to be a product of evolution, and that a different RNA-like (i.e., phosphorylated nucleosides), which were then coupled together to yield polymers identical in chemical structure toĬontemporary RNA. In one school, it is proposed that abiotic chemical processes initially gave rise to nucleotides Broadly defined, there are two schools of thought regarding the origin Of how the first nucleic acid molecules came to be. If we accept that nucleic acids must have appeared without the aid of coded proteins, we are still faced with the question In contrast, there is no obvious and general mechanism by which the amino acid sequence of a polypeptideĬan be transferred to a new polypeptide as part of a replication process. Furthermore, the rule-based one-to-one pairing of complementary bases in a Watson-Crick duplex ( Fig. 1) provides a robust mechanism for information transfer during replication that could have been operative from the advent of Life continues to strengthen this view ( Mandal and Breaker 2004 Gesteland and Atkins 2006). ![]() The ever-increasing list of processes that involve RNA in contemporary 1983) created widespread interest in an earlier proposal ( Woese 1967 Crick 1968 Orgel 1968) that nucleic acids were the first biopolymers of life, as nucleic acids transmit genetic information and could have onceīeen responsible for catalyzing a wide range of reactions. The discovery of catalytic RNA molecules in the early 1980s ( Kruger et al. The chemical emergence of life would appear simplified if one polymer was initially able to store and transfer informationĪs well as perform selective chemical catalysis-two essential features of life. Restrictive preconception-nucleic acids and noncoded peptides may have arisen independently and only later become dependent on each other. However, requiring that these biopolymers appeared strictly sequentially may be an overly This mutual dependence has been described as a “chicken-or-the-egg”ĭilemma concerning which came first. In contemporary life, nucleic acids provide the amino acid sequence information required for protein synthesis, while proteinĮnzymes carry out the catalysis required for nucleic acid synthesis. ![]() Is generally acknowledged of DNA, the product of evolution? If so, what chemical and structural features might have been more Here, weĬonsider studies of variations in these three distinct components of nucleic acids with regard to the question: Is RNA, as Nucleic acids may be optimally suited for their present roles-a situation that suggests refinement by evolution. (A, G, C, and T/U), the trifunctional moiety (ribose), and the linkage chemistry (phosphate esters) of contemporary Made possible by the application of synthetic and physical organic chemistry, have now provided evidence that the nucleobases However, theĭe novo synthesis of RNA using only plausible prebiotic chemistry has proven difficult, to say the least. Molecules subsequently provided support for the hypothesis that RNA was perhaps even the first polymer of life. Since the structure of DNA was elucidated more than 50 years ago, Watson-Crick base pairing has been widely speculated toīe the likely mode of both information storage and transfer in the earliest genetic polymers. ![]()
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