Figure 5

The relationship between system complexity and the present modeling possibilities. Whereas single genes can be modeled in molecular detail by stochastic simulations, (Top: left side), differential equations are already required for modeling small genetic circuits (centre left). Midsize genetic networks can at present only be modeled, when simplified, by concentrating on on-off switches, and large genetic networks are for the time being still out of reach of predictive simulations and modeling. Finally the last row shows that much information is available in the case of the consequences of the activity of single genes. The available information then gradually decreases from flow patterns of the activity of gene networks to functional modules of large networks. Activity patterns of large genetic networks are for the time being, still out of reach of predictive simulations and modeling. This is a simplified version of an illustration which indicates the different complexity of systems by Stefan Bornholdt, (Stefan Bornholdt, (2005). Less Is More in Modeling Large Genetic Networks. Perspectives: Systems biology. Science 310, 449-451). It is shown with permission of the author and the approval of Macmillan Publishers Ltd., in my forthcoming book in German: <Von Molekülen zu Zellen. 100 Jahre experimentelle Biologie. Betrachtungen eines Biochemikers>. It is reproduced here with permission of the GNT Verlag für Geschichte der Naturwissenschaften und der Technik. Diepholz. Stuttgart, Berlin.