Related Research Articles
The genetic code is the set of rules used by living cells to translate information encoded within genetic material into proteins. Translation is accomplished by the ribosome, which links proteinogenic amino acids in an order specified by messenger RNA (mRNA), using transfer RNA (tRNA) molecules to carry amino acids and to read the mRNA three nucleotides at a time. The genetic code is highly similar among all organisms and can be expressed in a simple table with 64 entries.
In biology, translation is the process in living cells in which proteins are produced using RNA molecules as templates. The generated protein is a sequence of amino acids. This sequence is determined by the sequence of nucleotides in the RNA. The nucleotides are considered three at a time. Each such triple results in addition of one specific amino acid to the protein being generated. The matching from nucleotide triple to amino acid is called the genetic code. The translation is performed by a large complex of functional RNA and proteins called ribosomes. The entire process is called gene expression.
The start codon is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome. The start codon always codes for methionine in eukaryotes and archaea and a N-formylmethionine (fMet) in bacteria, mitochondria and plastids.
The yeast mitochondrial code is a genetic code used by the mitochondrial genome of yeasts, notably Saccharomyces cerevisiae, Candida glabrata, Hansenula saturnus, and Kluyveromyces thermotolerans.
The ciliate, dasycladacean and Hexamita nuclear code is a genetic code used by certain ciliate, dasycladacean and Hexamita species.
The euplotid nuclear code is the genetic code used by Euplotidae. The euplotid code is a socalled "symmetrical code", which results from the symmetrical distribution of the codons. This symmetry allows for arythmic exploration of the codon distribution. In 2013, shCherbak and Makukov, reported that "the patterns are shown to match the criteria of an intelligent signal."
The alternative yeast nuclear code is a genetic code found in certain yeasts. However, other yeast, including Saccharomyces cerevisiae, Candida azyma, Candida diversa, Candida magnoliae, Candida rugopelliculosa, Yarrowia lipolytica, and Zygoascus hellenicus, definitely use the standard (nuclear) code.
The candidate division SR1 and gracilibacteria code is used in two groups of uncultivated bacteria found in marine and fresh-water environments and in the intestines and oral cavities of mammals among others. The difference to the standard and the bacterial code is that UGA represents an additional glycine codon and does not code for termination. A survey of many genomes with the codon assignment software Codetta, analyzed through the GTDB taxonomy system shows that this genetic code is limited to the Patescibacteria order BD1-5, not what are now termed Gracilibacteria, and that the SR1 genome assembly GCA_000350285.1 for which the table 25 code was originally defined is actually using the Absconditibacterales genetic code and has the associated three special recoding tRNAs. Thus this code may now be better named the "BD1-5 code".
The ascidian mitochondrial code is a genetic code found in the mitochondria of Ascidia.
The alternative flatworm mitochondrial code is a genetic code found in the mitochondria of Platyhelminthes and Nematodes.
The Blepharisma nuclear code is a genetic code found in the nuclei of Blepharisma.
The chlorophycean mitochondrial code is a genetic code found in the mitochondria of Chlorophyceae.
The trematode mitochondrial code is a genetic code found in the mitochondria of Trematoda.
The Thraustochytrium mitochondrial code is a genetic code found in the mitochondria of the labyrinthulid protist Thraustochytrium aureum. The mitochondrial genome was sequenced by the Organelle Genome Megasequencing Program.
The pachysolen tannophilus nuclear code is a genetic code found in the ascomycete fungus Pachysolen tannophilus.
The karyorelictid nuclear code is a genetic code used by the nuclear genome of the Karyorelictea ciliate Parduczia sp. This code, along with translation tables 28 and 31, is remarkable in that every one of the 64 possible codons can be a sense codon. Translation termination probably relies on context, specifically proximity to the poly(A) tail.
The Condylostoma nuclear code is a genetic code used by the nuclear genome of the heterotrich ciliate Condylostoma magnum. This code, along with translation tables 27 and 31, is remarkable in that every one of the 64 possible codons can be a sense codon. Experimental evidence suggests that translation termination relies on context, specifically proximity to the poly(A) tail. Near such a tail, PABP could help terminate the protein by recruiting eRF1 and eRF3 to prevent the cognate tRNA from binding.
The Mesodinium nuclear code is a genetic code used by the nuclear genome of the ciliates Mesodinium and Myrionecta.
The peritrich nuclear code is a genetic code used by the nuclear genome of the peritrich ciliates Vorticella and Opisthonecta.
References
This article incorporates text from the United States National Library of Medicine, which is in the public domain. [2]
- 1 2 Záhonová, Kristína; Kostygov, Alexei Y.; Ševčíková, Tereza; Yurchenko, Vyacheslav; Eliáš, Marek (2016). "An Unprecedented Non-canonical Nuclear Genetic Code with All Three Termination Codons Reassigned as Sense Codons". Current Biology. 26 (17): 2364–2369. doi: 10.1016/j.cub.2016.06.064 . PMID 27593378.
- ↑ Elzanowski A, Ostell J, Leipe D, Soussov V. "The Genetic Codes". Taxonomy browser. National Center for Biotechnology Information (NCBI), U.S. National Library of Medicine. Retrieved 18 November 2016.