Minimum Forms of Control in Prokaryotes and their Computational Meaning

摘要

The main goal of our work is to point out some aspects of basic control in biological and technical systems discussing similarities and differences. To keep things manageable and somewhat simpler we restrict our view to unicellular organisms and in particular to prokaryotes. There we find, as a matter of fact, minimum forms of molecular control structures that can be related to computational constructs, and that, in a formal sense, build an algorithmically sufficient set. Thus, the main result of this paper is that even prokaryotic cells have Turing machine power. The way biological control structures are combined within the cell to build more complex forms of control flow seems, however, to be different from that desirable or normally envisaged for the realization of technical systems. Biological computation is highly parallel and at the same time data and event driven, and therefore not simply amenable to a description in form of physically and functionally coherent modules. This and other obvious scale-specific aspects of the prokaryotic world suggest that the importance of cell-based approaches, in particular for flexible manufacturing systems (FMS), is questionable, at least in the sense that the level of abstraction and the point of view must be carefully chosen in order to get some profit from the biological model.