SHORT COUMMUNICATION Arbitrariness is not enough: towards a functional approach to the genetic code L ’udmila Lackova ´ 1 • Vladimı ´r Matlach 1 • Dan Falty ´nek 1 Received: 14 October 2016 / Accepted: 2 May 2017 / Published online: 9 May 2017 Ó Springer-Verlag Berlin Heidelberg 2017 Abstract Arbitrariness in the genetic code is one of the main reasons for a linguistic approach to molecular biol- ogy: the genetic code is usually understood as an arbitrary relation between amino acids and nucleobases. However, from a semiotic point of view, arbitrariness should not be the only condition for definition of a code, consequently it is not completely correct to talk about ‘‘code’’ in this case. Yet we suppose that there exist a code in the process of protein synthesis, but on a higher level than the nucleic bases chains. Semiotically, a code should be always asso- ciated with a function and we propose to define the genetic code not only relationally (in basis of relation between nucleobases and amino acids) but also in terms of function (function of a protein as meaning of the code). Even if the functional definition of meaning in the genetic code has been discussed in the field of biosemiotics, its further implications have not been considered. In fact, if the function of a protein represents the meaning of the genetic code (the sign’s object), then it is crucial to reconsider the notion of its expression (the sign) as well. In our contri- bution, we will show that the actual model of the genetic code is not the only possible and we will propose a more appropriate model from a semiotic point of view. Keywords Arbitrariness Á Biosemiotics Á Genetic code Á Protein function Á Semiotics The arbitrary nature of the genetic code 1 was probably one of the reasons that led biologists to treat analogies between the genetic code and natural languages and to implement linguistic terminology for new discoveries in molecular biology and genetics. As a result, notions like code, tran- scription, and translation have become accepted scientific terms in biology. Already Francis Crick, after having deciphered the genetic code, suggested its arbitrary nature. He wrote: ‘‘The present experimental evidence, then, makes it unlikely that every amino acid interacts stereo- chemically with either its codon or its anticodon.’’ (Crick 1968, 371). Two years later another biologist, Jacques Monod, declared the arbitrary nature of the genetic code, this time explicitly: ‘‘There is no direct steric relationship between the coding triplet and the encoded amino acid. The code […] seems chemically arbitrary.’’ (Monod 1970, 123). Arbitrariness was defined by Ferdinand de Saussure as one of the three main principles of languages. According to de Saussure, a linguistic sign and any kind of sign ‘‘is arbitrary in that it has no natural connection’’ between the sign and its object (De Saussure 1916, 69). It means that there is no natural direct connection between the word dog and its meaning (the object in general, in this case any dog). In other words, what is referred to do not necessitate the form of what is referring (the referent). It is important & L ’udmila Lackova ´ ludmila.lackova01@upol.cz Vladimı ´r Matlach vladimir.matlach@upol.cz Dan Falty ´nek dan.faltynek@upol.cz 1 Department of General Linguistics, Palacky ´ University, Kr ˇı ´z ˇkovske ´ho 14, 771 47 Olomouc, Czech Republic 1 In biology, the term ‘‘genetic code’’ is understood as a table of 64 codon triplets specifying amino acids or STOPs. The table is only a schematisation of a real connections between codon triplets and amino acids that exist in nature in form of strings (or folded strings). In this article, the term ‘‘genetic code’’ is used rather in reference to strings of codon triplets and strings of amino acids and relation between them, not in reference to its schematic representation. 123 Theory Biosci. (2017) 136:187–191 DOI 10.1007/s12064-017-0246-1