An alternative to the RNA World Hypothesis

Abstract

The RNA world hypothesis for the origin of life is widely accepted in spite of the complexity of RNA synthesis. An alternative hypothesis is advanced for the origin and evolution of protein and nucleic acid synthesis. From an early stage synthesis of the evolutionary predecessors of nucleic acids and polypeptides was coupled. This evolved into an RNA replication process that used 3'-aminoacyl-NMP monomers (N= pyrimidine or purine) with a singlet coding system in which the four bases coded for glycine, alanine, valine and aspartic acid. Ribosomal protein synthesis (RPS) evolved from coupled replication by using tRNAs and separating fidelity checking and peptide bond formation functions into small and large ribosomal subunits. Continuity was maintained during the transition to the triplet process by using the same catalysts that aminoacylated NMPs to aminoacylate four different bases at the 3' ends of the original tRNAs. Four GNC codons used the central base to designate the same four amino acids that were coded in singlet replication. Triplet-coded protein synthesis had the advantage of producing multiple copies of protein from a single copy of RNA, and eventually replaced protein synthesis via singlet-coded replication. Evolution of the simple triplet-coded process into RPS is described.

Pathways of Genetic Code Evolution in Ancient and Modern Organisms

“…Although the RNA World hypothesis is widely accepted (Joyce 2000;Bernhardt 2012;Higgs and Lehman 2015), there are also Carter 2015;Francis 2015). If protein sequences were present before the origin of the ribosome and the genetic code, there must have been a different mechanism of specifying and synthesizing amino acid sequences, such as a direct structural interaction of proteins and RNA (Carter 2015) or the mechanism of cosynthesis of proteins and nucleic acids proposed by Francis (2011). These mechanisms seem speculative, however, and are not yet supported by experiment.…”

Life Origin on Earth, Insights among Different Arguments

“…This editorial gives our visions to this matter. Certainly, besides biologists, mathematical/physicsmajored scientists are also very useful to take parts these researches and finally offer their contributions [15][16][17][18]. Let's decide which answer is right as early as possible.…”

Life Origin on Earth, What is the Right Answer?

“…This editorial gives our visions to this matter. Certainly, besides biologists, mathematical/ physics-majored scientists are also useful to take parts these researches and final offer their contributions [15][16][17][18]. Let's decide what is the right answer.…”