Why nucleotides when mixed together in the absence of a template RNA molecule do not readily link up into a chain? We know that the bond between nucleotides side by side is stronger than the hydrogen bond between the two RNA strands, a negative and a positive one. Shouldn't then the nucleotides form chains of RNA more readily by just attaching to each other than making a dimeric RNA through a lock and key type latching?

The book that caused this question is "What Is Life?" by A. Pross (p.68), who unfortunately doesn't provide an answer.

  • $\begingroup$ Before asking questions about the chemistry of biological reactions you should learn some basic chemistry. This online resource may help. The role of enzymes in relation to the thermodynamics of reactions is also key. $\endgroup$ – David Nov 26 '17 at 22:21
  • $\begingroup$ RNA nucleotides will form chains spontaneously, having a catalyst however makes it happen faster. $\endgroup$ – John Nov 27 '17 at 21:19

The dNTPs don't just come together. They require a polymerase to break off 2 phosphates and bond the hydroxyl group to the remaining phosphate. To take a nucleotide triphosphate and add it to a growing chain of nucleic acid, the polymerase checks the fidelity of the hydrogen bonds that precede the new bond. dNTPs provide the energy for this reaction, but the enzymes require a double stranded molecule to copy. In other words, they can copy double stranded nucleic acid, but not form it from scratch.

  • $\begingroup$ Thanks for your answer! I only would like to clarify if the same laws apply to the self-replicating RNA (autocatalytic), with no enzymes, since the book is talking about prebiotic time. $\endgroup$ – Denis Nov 26 '17 at 12:48
  • $\begingroup$ @Karl: DNA polymerase theta is capable of template-independent DNA synthesis. Kent et al. (2016) Elife 5: e13740. ncbi.nlm.nih.gov/pubmed/27311885 $\endgroup$ – user37894 Nov 27 '17 at 9:34

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