Proto cell model

To sum up, we envision a (proto)cell containing molecules. With a supply of chemicals available to the cell, these molecules replicate through catalytic reactions, so that their numbers within a cell increase. When the total number of molecules exceeds a given threshold, the cell divides into two, with each daughter cell inheriting half of the molecules of the mother, chosen randomly. Regarding the choice of chemical species and the reaction, we have a discussion later for specific models (see Fig. 1 for a schematic representation). 

Our main concern here is the dynamics of these molecule numbers A, of the species i in relationship with the condition of the recursive growth of the (proto)cell. In our model there are four basic parameters the total number of molecules N, the total number of molecular species k, the mutation rate p, and the reaction path rate p. By carrying out simulations of this model (choosing a variety of parameter values N, k, p, and p) and also by taking various random networks, we have found that the behaviors are classified into the following three phases [32,33] ... 

Oxygen carriers would presumably not have been needed at a very early stage in the evolution of cells. Models of reversible complexes of iron and oxygen have been difficult to find. The only two clear examples are ferrous PROTO (or meso-) porphyrinimidazole in dry pyridine 178), and ferrous dimethylgloxime with amines 179). Many reversible oxygen-cobaltous complexes are known 180). 

M. Schuster, T. Rager, A. Noda, K. D. Kreuer, and J. Maier, About the choice of the proto-genic group in PEM separator materials for intermediate temperature, low humidity operation A critical composition of sulfonic acid, phosphonic acid and imidazole functionafized model compounds. Fuel Cells 5(3), 355-365 (2005). 

---