There are three essential macromolecules in all species of life. Ribonucleic acid (RNA) is one of these three, and RNA has the amazing ability as a single stranded molecule to assume three-dimensioned shapes by means of the multiple hydrogen bonding that form its secondary structural scaffolding. The other two essential macromolecules are deoxyribonucleic acid (DNA) and proteins; of these two, RNA has many similarities to proteins in function and similarities to DNA in chemical structure. There are double stranded RNA as well, but they are rare. Single stranded RNA catalyzes biological reactions, is a receiver and transmitter for cellular signals, and assists in the control of gene expressions.
As of 2011, single stranded RNA has been the object of seven Nobel Prizes. Much research between the prizes made discoveries of the duties of RNA, leading to significant advances in biological and medical sciences. Single stranded RNA was found in 1868, yet mischaracterized, and it was not until 1959 that it received the focus of a Nobel, when Ochoa and Kornberg received the Nobel Prize in Medicine after synthesizing RNA in a lab through the use of an enzyme — again mischaracterized; it was not a true synthesis but a degradation procedure. In the 1960s and 1970s, two more prizes were awarded for discoveries that single stranded RNA not only could carry genetic information, but also works as a catalyzer of biological reactions and for the discovery that retroviruses could, via enzymes, replicate RNA into DNA, making this type of replication a two-way street. In the 1980s through to 2006, four more prizes were given for discoveries in RNA splicing, more catalyzing functions, microRNA functions, and RNA transcription.
Single stranded RNA is instrumental in protein synthesis; when proteins are formed in ribosomes, it is messenger RNA (mRNA) that directs the assembly and together with transfer RNA (tRNA) delivers accompanying amino acids to bond and form the proteins. The ribosomal factories of proteins receive genetic information from mRNA and the 80 nucleotides of tRNA are instrumental in the translation of amino acids to the newly forming proteins. With the use of DNA as a template, an enzyme known as RNA polymerase transcribes RNA for new strands of single stranded RNA. This same enzyme uses templates of RNA when RNA viruses such as poliovirus attempt to replicate their virus material. There is a method to measure and screen for single stranded RNA function important in understanding the bond between RNA and proteins. Nucleotide analog interference mapping (NAIM) discovers the identity of particular RNA molecules that bind to proteins less well than the bindings of wild-type RNA, to better understand the mediating binding behavior with proteins.
As RNA carries genetic information, RNA viruses contain replications of RNA in their genome as well as a variety of proteins encoded by that genome. Some proteins protect this viral genome as it translates itself to a new cell host. These viruses with resident RNA replications in turn reverse transcribe DNA and form new single stranded RNA that spreads viruses further. There are four groups of RNA viruses that spread measles, mumps, rabies, influenza, yellow fever and equine encephalitis among a host of other diseases, and each group has its own method of replicating a virus genome.
It is known that rhinoviruses, including the common cold, are single stranded RNA that replicate in the cytoplasm of a cell by processing a viral protease that results in release of proteins infected by a virus. Single stranded RNA is also linked to a type of inflammation that may be responsible for fetal cardiac fibrosis that can lead to heart block in a fashion of an autoimmune reaction, leading to congenital heart defects. There are discoveries about RNA, however, that may use RNA to silence genes within the body that might cause disease. Knowing that there are small portions of RNA that interfere with protein manufacturing, some believe some day, single stranded RNA will deliver pharmaceuticals directly to proteins.