Biosemiotics asserts the idea that semiosis is fundamental to life, and that all living creatures are therefore semiotic systems. The idea itself is strongly supportedby the evidence of the genetic code — but thus far it has made little impact in the scientific world, and is largely regarded as the basis for a philosophy of meaning, rather than a basis for a science of meaning. This is regrettable, but perhaps understandable from the scientists’ point of view. Scientists know that the (...) cell is the necessary unit of all life. I will argue here, then, that Biosemiotics can become a science only if it can prove that the cell is, in fact, a semiotic system — i.e., that semiosis exists at the cellular level. To do this, we first need to define what is semiosis, so that we can be explicit about what exactly constitutes a semiotic system. So far, we have had two main answers to this question. One is the model proposed by Saussure, who defined a semiotic system as a duality of ‘signifier and signified’. The other is the model of Peirce, who pointed out that interpretation is an essential component of semiosis and defined a semiotic system as a triad of ‘sign, object and interpretant’. After the discovery of the genetic code, each of these two models have been applied to biology and have given rise to two distinct schools of biosemiotics. One is the school of Marcel Florkin (1974), which is based on the model of Saussure, and the other is the school of Thomas Sebeok (1972, 2001), which is based on the model of Peirce. Unfortunately, neither of them can be applied to the cell, and that is why most biologists continue to be skeptical about biosemiotics. There is however a third model of semiosis that is actually applicable to the cell. It is based on the theory that the cell is a trinity of genotype, phenotype and ribotype (Barbieri 1981, 1985, 2003). Here, the ribotype is the ribonucleoprotein system of the cell and represents its ‘codemaker’, i.e., the seat of the genetic code. This model assumes that semiosis is defined by coding, not by interpretation, and is therefore referred to as the code model of semiosis. This paper is dedicated to illustrating this third model and, above all, to showing that the cell is a true semiotic system. (shrink)