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A Hypothetical Pathway from the NRA to the DNA World

journal contribution
posted on 2023-05-16, 14:54 authored by Line, MA
If the DNA world was preceded by a RNA world as widely suggested a rational pathway should be discernable to link the two. This report uses as a starting point a membrane-enclosed ribozyme capable of polymerising itself and its counterpart copy. As molecular complexity increased, it is suggested that a consortia of the initial ribozyme polymerase and chaperone molecules formed a complex specifically for RNA replication. A mutation in one of several copy-genomes coding for these replication machines then led in step-wise fashion to a proto-ribosome that increasingly inserted specific amino acids instead of nucleotides into a growing RNA chain, the driving force being selection for improved or new function. Eventually the nucleotides would be entirely displaced in this proto-ribosome, after which the ribose-phosphate linkage would be replaced by peptide linkage. The final steps would be the formation of DNA from the RNA genomic material viareverse transcriptase, coupled with the evolution of enzymes for DNA polymerisation and transcription. At this point the original RNA-replicator machinery would be redundant and eliminated, the RNA genomic material would become mRNA and the present-day function of the ribosome would be fixed. In the scenario described a mechanism for the selection for L-amino acids becomes evident. © Springer 2005.

History

Publication title

Origins of Life and Evolution of Biospheres

Volume

35

Issue

4

Pagination

395-400

ISSN

0169-6149

Department/School

Tasmanian Institute of Agriculture (TIA)

Publisher

Springer-Verlag Dordrecht

Place of publication

Netherlands

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the environmental sciences

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