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The genetic code is a key part of the history of life, according to one version of which self-replicating RNA molecules preceded life as we know it. This is the RNA world hypothesis . Under this hypothesis, any model for the emergence of the genetic code is intimately related to a model of the transfer from ribozymes (RNA enzymes) to proteins ...
While there is much commonality, different parts of the tree of life use slightly different genetic codes. [1] When translating from genome to protein, the use of the correct genetic code is essential.
It can also be represented in a DNA codon table. The DNA codons in such tables occur on the sense DNA strand and are arranged in a 5 ′-to-3 ′ direction. Different tables with alternate codons are used depending on the source of the genetic code, such as from a cell nucleus, mitochondrion, plastid, or hydrogenosome. [5]
Perhaps most tellingly, the genetic code (the "translation table" between DNA and amino acids) is the same for almost every organism, meaning that a piece of DNA in a bacterium codes for the same amino acid as in a human cell. ATP is used as energy currency by all extant life.
DNA contains the genetic information that allows all forms of life to function, grow and reproduce. However, it is unclear how long in the 4-billion-year history of life DNA has performed this function, as it has been proposed that the earliest forms of life may have used RNA as their genetic material.
When DNA is transcribed to RNA, its complement is paired to it. DNA codes are transferred to RNA codes in a complementary fashion. The encoding of proteins is done in groups of three, known as codons. The standard codon table applies for humans and mammals, but some other lifeforms (including human mitochondria [9]) use different translations. [10]
The Consortium for the Barcode of Life (CBOL) was an international initiative dedicated to supporting the development of DNA barcoding as a global standard for species identification. [1] CBOL's Secretariat Office is hosted by the National Museum of Natural History, Smithsonian Institution, in Washington, DC.
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 ...