Search results
Results from the WOW.Com Content Network
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] It had multiple DNA ...
The RNA world hypothesis describes an early Earth with self-replicating and catalytic RNA but no DNA or proteins. [178] Many researchers concur that an RNA world must have preceded the DNA-based life that now dominates. [179] However, RNA-based life may not have been the first to exist.
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. RNA ...
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 ...
It has become widely accepted in science [1] that early in the history of life on Earth, prior to the evolution of DNA and possibly of protein-based enzymes as well, an "RNA world" existed in which RNA served as both living organisms' storage method for genetic information—a role fulfilled today by DNA, except in the case of RNA viruses—and ...
Adenylate-uridylate-rich elements (AU-rich elements; AREs) are found in the 3' untranslated region (UTR) of many messenger RNAs that code for proto-oncogenes, nuclear transcription factors, and cytokines. AREs are one of the most common determinants of RNA stability in mammalian cells. [1]
DNA and RNA also contain other (non-primary) bases that have been modified after the nucleic acid chain has been formed. In DNA, the most common modified base is 5-methylcytosine (m 5 C). In RNA, there are many modified bases, including those contained in the nucleosides pseudouridine (Ψ), dihydrouridine (D), inosine (I), and 7-methylguanosine ...
All living cells contain both DNA and RNA (except some cells such as mature red blood cells), while viruses contain either DNA or RNA, but usually not both. [15] The basic component of biological nucleic acids is the nucleotide, each of which contains a pentose sugar (ribose or deoxyribose), a phosphate group, and a nucleobase. [16]