Biology Reference
In-Depth Information
Chapter 3
Chemistry
3.1 Principle of Self-Organization and Dissipative Structures
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.,
0) chemical reactions themselves. Such phenomena are
referred to as
self-organization,
and physicochemical systems exhibiting self-orga-
nization 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 extracel-
lular 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 dissipa-
tion 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
.
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