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The integrity of the DNA was maintained by a group of repair enzymes including DNA topoisomerase. [20] If the genetic code was based on dual-stranded DNA, it was expressed by copying the information to single-stranded RNA. The RNA was produced by a DNA-dependent RNA polymerase using nucleotides similar to those of DNA. [15]
A second version of the central dogma is popular but incorrect. This is the simplistic DNA → RNA → protein pathway published by James Watson in the first edition of The Molecular Biology of the Gene (1965). Watson's version differs from Crick's because Watson describes a two-step (DNA → RNA and RNA → protein) process as the central ...
The structure of the ribosome has been called the "smoking gun", with a central core of RNA and no amino acid side chains within 18 Å of the active site that catalyzes peptide bond formation. [184] [180] [185] The concept of the RNA world was proposed in 1962 by Alexander Rich, [186] and the term was coined by Walter Gilbert in 1986.
Patrick Forterre has been working on a novel hypothesis, called "three viruses, three domains": [99] that viruses were instrumental in the transition from RNA to DNA and the evolution of Bacteria, Archaea, and Eukaryota. He believes the last universal common ancestor [99] was RNA-based and evolved RNA viruses. Some of the viruses evolved into ...
The chirality of DNA, RNA, and amino acids is conserved across all known life. As there is no functional advantage to right- or left-handed molecular chirality, the simplest hypothesis is that the choice was made randomly by early organisms and passed on to all extant life through common descent.
The ability of RNA molecules to adopt specific tertiary structures is essential for their biological activity, and results from the single-stranded nature of RNA. In many ways, RNA folding is more highly analogous to the folding of proteins rather than to the highly repetitive folded structure of the DNA double helix. [12]
In accordance with the central dogma of molecular biology, RNA passes information between the DNA of a genome and the proteins expressed within an organism. [1] Therefore, from an evolutionary standpoint, a mutation within the DNA bases results in an alteration of the RNA transcripts, which in turn leads to a direct difference in phenotype.
They also hypothesized the existence of an intermediary between DNA and its protein products, which they called messenger RNA. [6] Between 1961 and 1965, the relationship between the information contained in DNA and the structure of proteins was determined: there is a code, the genetic code , which creates a correspondence between the ...