This paper proceeds from the hypothesis that two kinds of convergence can be distinguished: a theoretical convergence, when several scientific fields relate to the same model; and an instrumental convergence, when a scientific discipline provides other disciplines with scientific tools which are necessary to develop experiences. We will thus investigate the convergence between molecular biology and information science to discover that, in the 1960s, the convergence was theoretical, since molecular biology and genetics were built upon a metaphor drawn from computer science. Instrumental convergence was not reached until the development of microelectronics and microcomputers and the apparition of technologies specifically adjusted for biological (and medical) research. The current situation is characterized by the following paradox: biology, while becoming more and more performing, thanks to labs on chips, tends to free itself from the metaphor from which it originated and by which it was inspired for a long time.