Bregestowski P D
Zh Evol Biokhim Fiziol. 2015 Jan-Feb;51(1):64-74.
The most widely accepted modern 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 the information transfer and all the processes necessary for the functioning of the primary systems were provided by replicating RNA molecules. The essence of the "RNA World" hypothesis is based on two postulates: 1) at the initial stages of the origin of life, RNA molecules performed all functions necessary for reproduction and replication of biological molecules: informational, catalytic and structural; 2) at a certain stage of evolution arose separation of RNA and DNA, appeared genetically encoded proteins and occurred a transition to the modern world of living systems functioning. However, the analysis shows that the hypothesis of "RNA World" has a number of unsurmountable problems of chemical and informational nature. The biggest of them are: a) the unreliability of the initial components synthesis; b) a catastrophic rise of polynucleotide chains instability with their elongation; c) catastrophically low probability of formation of sequences possessing meaningful information; d) lack of a mechanism determining the regularities division of the membrane vesicles permeable to nitrogen bases and other RNA components; e) lack of driving forces for the transition from the RNA world to the much more complex world based on DNA and RNA. Therefore, the "RNA World" scenario seems unlikely.
导致地球上首批细胞出现的最被广泛接受的现代益生元进化设想是“RNA世界”——早期地球生物圈的一个假设阶段,当时信息传递以及初级系统运作所需的所有过程均由可复制的RNA分子提供。“RNA世界”假说的核心基于两个假设:1)在生命起源的初始阶段,RNA分子执行生物分子复制和繁殖所需的所有功能:信息功能、催化功能和结构功能;2)在进化的某个阶段,RNA与DNA分离,出现了基因编码蛋白质,并发生了向现代生命系统运作世界的转变。然而,分析表明,“RNA世界”假说存在一些化学和信息性质的无法克服的问题。其中最大的问题是:a)初始成分合成的不可靠性;b)多核苷酸链随着延长其不稳定性灾难性增加;c)形成具有有意义信息的序列的概率极低;d)缺乏决定对氮碱基和其他RNA成分可渗透的膜囊泡规则分裂的机制;e)缺乏从RNA世界向基于DNA和RNA的更为复杂的世界转变的驱动力。因此,“RNA世界”设想似乎不太可能。