Universality and individuality as complementary factors to optimize and reproduce cell populations

Abstract.

Irreversible thermodynamics allows us to formulate the law of mass action for a large number of reactions running off in open systems. By applying it to cell populations, these ensembles are supposed to be installed by defined increments. Stationary ensembles are then predicted to be optimized in the sense of thermodynamics of irreversible processes. General relations for describing the cell size distribution or the intracellular length distribution of proteins are deduced. During cell growth and multiplication, the cell size distributions change systematically in the course of time; yet, they are all reproduced by only adjusting the standard energy. This phenomenon is considered to originate with process-dependent constraints according to irreversible thermodynamics characterized by hidden variables. In agreement with the theoretical demands, all the different realizations belong to the same universal cell size distribution. Moreover, the universal stationary cell size distribution is classified by a single parameter, p. It is then of great importance that the stationary size distributions of cells of bacteria, yeast and human melanocytes all belong to the p=3 type, irrespective of the external conditions and of the individual chemical structure of the constituents. Universality also classifies the intracellular length distribution of proteins. The results discussed are enough to uncover as to how the genetically perfect production of the individual constituents and the thermodynamic optimization of the whole cell population are logistically coordinated.