Chemistry

Abstract

The phenomenon of spontaneous generation of spatial patterns of chemical concentration gradients was first observed in a purely chemical system in 1958 (see Fig. 3.1) (Babloyantz 1986; Kondepudi and Prigogine 1998; Kondepudi 2008) and inside the living cell in 1985 (see Fig. 3.2) (Sawyer et al. 1985). These observations demonstrate that, under appropriate experimental conditions, it is possible for chemical reactions to be organized in space and time to produce oscillating chemical concentrations, metastable states, multiple steady states, fixed points (also called attractors), etc., all driven by the free energy released from exergonic (i.e., ΔG < 0) chemical reactions themselves. Such phenomena are referred to as self-organization, and physicochemical systems exhibiting self-organization are called dissipative structures (Prigogine 1977; Babloyantz 1986; Kondepudi and Prigogine 1998; Kondepudi 2008). It has been found convenient to refer to dissipative structures also as X-dissipatons, X referring to the function associated with or mediated by the dissipative structure. For example, there is some evidence (Lesne 2008; Stockholm et al. 2007) that cells execute a set of gene expression pathways (GEPs) more or less randomly in the absence of any extracellular signals until environmental signals arrive and bind to their cognate receptors, stabilizing a subset of these GEPs. Such mechanisms would account for the phenomenon of the phenotypic heterogeneity among cells with identical genomes (Lesne 2008; Stockholm et al. 2007). Randomly expressed GEPs are good examples of dissipatons, since they are dynamic, transient, and driven by dissipation of metabolic energy. Ligand-selected GEPs are also dissipatons. All living systems, from cells to multicellular organisms, to societies of organisms and to the biosphere, can be viewed as evolutionarily selected dissipatons. As indicated above, attractors, fixed points, metastable states, steady states, oscillators, etc., that are widely discussed in the nonlinear dynamical systems theory (Scott 2005) can be identified as the mathematical representations of dissipatons.