'RNA World', a highly improbable scenario of the origin and early evolution of life on earth
| Autor: | P. D. Bregestovski |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Journal of Evolutionary Biochemistry and Physiology. 51:72-84 |
| ISSN: | 1608-3202 0022-0930 |
| DOI: | 10.1134/s0022093015010111 |
| Popis: | The most accepted and widespread contemporary scenario of prebiotic evolution that led to the emergence of the first cells on our planet is the “RNA World”, a hypothetical period of the early Earth’s biosphere when information transfer and all of the processes necessary for the functioning of prebiotic living systems were provided by RNA molecules. The “RNA World” hypothesis is based on two postulates. (1) At the initial stages of life, RNA molecules performed all the functions necessary for the reproduction of biological molecules: informational, catalytic and structural; (2) At a certain stage of evolution, there occurred a functional separation of RNA and DNA, emergence of genetically encoded proteins and transition to the modern world of living systems. However, the analysis shows that the “RNA World” hypothesis suffers from a number of insurmountable problems of chemical and informational nature. The biggest of them are: (a) unreliability of the synthesis of starting components; (b) catastrophically increasing instability of the polynucleotide molecules as they elongate; (c) exceedingly low probability of meaningful sequences; (d) lack of the mechanism that would generate membrane-bound vesicles able to divide regularly and permeable to the nitrogenous bases and other RNA components; (e) absence of driving forces for the transition from the “RNA world” to the much more complex “DNA-RNA world”. Therefore, the “RNA World” scenario is highly improbable. |
| Databáze: | OpenAIRE |
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