The properties of the phosphate uptake system of the cyanobacterium Anacystis nidulans have been studied during the transition from a phosphate-deficient non-growing state to a non-deficient growing state. In the phosphate-deficient state the high affinity phosphate transport system in the cell membrane is extremely adaptive. As a result of these adaptive features the phosphate transport system cannot be described by determinate, fixed parameters, because the transport system is influenced by the measurement of the uptake process itself. When the growing state (...) has been initiated by a persisting phosphate pulse, the transport system rapidly loses its adaptive features and can then be characterized by determinate parameters that remain unchanged for a long period of time, even if no uptake occurs in that time. Depending on the amount of phosphate stored during a pulse the cell makes a choice between slow or fast growth. In the latter case the light harvesting and energy converting machinery is completely reorganized before growth commences. Thereby the components of this machinery conform to each other and to the stable properties of the phosphate transport system. It is suggested that the mutual adjustment of these adaptive energy converting subunits is guided by attractors that function as the final cause for the development of the whole system.An application of this model to an analysis of the selforganization of aquatic ecosystems is discussed. (shrink)