DNA and RNA codon tables: Difference between revisions

Revision as of 23:31, 1 August 2024

Revision as of 04:00, 9 August 2024

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[[File:Codon wheels.png|thumb|The second codon position best determines amino acid hydrophobicity. Color-coding: hydrophobicity from microenvironment in folded proteins <ref>{{cite journal |last1=Bandyopadhyay |first1=Debashree |last2=Mehler |first2=Ernest L. |date=August 2008 |title=Quantitative expression of protein heterogeneity: Response of amino acid side chains to their local environment. |journal=Proteins |volume=72 |number=2 |pages=646-59 |doi=10.1002/prot.21958|pmid=18247345 }}</ref>]]

The classical table/wheel of the standard genetic code is arbitrarily organized based on codon position 1. Saier ,<ref>{{cite journal |last1=Saier |first1=Milton H. Jr. |date=10 July 2019 |title=Understanding the Genetic Code. |journal=J Bacteriol |volume=201 |number=15 |pages=e00091-19 |doi=10.1128/JB.00091-19|pmid=31010904 |pmc=6620406 }}</ref>, following observations from ,<ref>{{cite journal |last1=Muto |first1=A. |last2=Osawa |first2=S. |date=January 1987 |title=The guanine and cytosine content of genomic DNA and bacterial evolution. |journal=Proc Natl Acad Sci USA |volume=84 |number=1 |pages=166-9 |doi=10.1073/pnas.84.1.166|pmid=3467347 |pmc=304163 }}</ref>, showed that reorganizing the wheel based instead on codon position 2 (and reordering from UCAG to UCGA) better arranges the codons by the hydrophobicity of their encoded amino acids. This suggests that early ribosomes read the second codon position most carefully, to control hydrophobicity patterns in protein sequences.

The first table—the standard table—can be used to translate [[nucleotide]] triplets into the corresponding amino acid or appropriate signal if it is a start or stop codon. The second table, appropriately called the inverse, does the opposite: it can be used to deduce a possible triplet code if the amino acid is known. As multiple codons can code for the same amino acid, the [[International Union of Pure and Applied Chemistry]]'s (IUPAC) [[nucleic acid notation]] is given in some instances.