The present work continues studies of the mathematical model of a metabolic process of the Krebs cycle. We study the dependence of its cyclicity on the cell respiration intensity determined by the formation level of carbon dioxide. We constructed the phase-parametric characteristic of the consumption of a substrate by a cell depending on the intensity of the metabolic process of formation of the final product of the oxidation. The scenarios of all possible oscillatory modes of the system are constructed and studied. The bifurcations with period doubling and with formation of chaotic modes are found. Their attractors are constructed. The full spectra of indices and divergencies for the obtained modes, the values of KS-entropies, horizons of predictability, and Lyapunov dimensions of strange attractors are calculated. Some conclusions about the structural-functional connections of the cycle of tricarboxylic acids and their influence on the stability of the metabolic process in a cell are presented.
K e y w o r d s : Krebs cycle, metabolic process, self-organization, strange attractor, bifurcation, Feigenbaum scenario.One of the possible problems of synergetics is the study of the internal dynamics of metabolic processes in cells. Its solution allows one to find the structural-functional connections defining the self-organization of these processes and to answer the question how the catalyzed enzymatic reactions create the internal space-time ordering of the cell life.The most general metabolic process in cells is the cycle of tricarboxylic acids [1]. This is the key stage of the respiration of all cells. In its course, the di-and tricarbon compounds, which are formed as intermediate products in the transformation of carbohydrates, fats, and proteins, are transformed up to CO 2 . In this case, the released hydrogen is oxidized further up to water, by taking the direct participation in the synthesis of ATP, being the universal energy source.Studies of the functioning of the Krebs cycle were carried out both experimentally and theretically in [2][3][4][5][6][7][8][9][10].In the study of the given process, we use the mathematical model of the growh of cells Candida utilis on ethanol, which was developed by Professor V.P. Gachok [11,12]. The analogous modeling of a growth of cells was performed independently by J. Monod, V.S. Podgorskii, L.N. Drozdov-Tikhomirov, N.T. Rakhimova, G.Yu. Riznichenko, and other researchers [13][14][15][16][17].With the help of this model, the unstable modes in the cultivation of cells observed in experiments were considered. The kinetic curves of the chaotic dynamics obtained with the help of computational experiments were in agreement with experimental data [18]. Then the given model was modified and refined in [19] due to the account for the influence of the CO 2 level on the respiration intensity. With the help of the model, the structural-functional connections of the metabolic process in a cell, which cause the appearance of complicated oscillations in the metabolic process, were invest...