Physics - Molecular Theory of the Living Cell - page 6

Thermodynamic System

Equilibrium System Non-equilibrium System

Near-Equilibrium Far-From-Equilibrium

Dissipative Structures

Resting State Activated State

Fig. 2.1 The relationship between thermodynamic systems and dissipative structures

i.e., D X X initial . The importance of Gibbs free energy in biology stems

from the fact that under biological conditions (most often characterized by constant
pressure and temperature), all spontaneous changes are accompanied by Gibbs free
energy decreases, i.e., by negative Gibbs free energy changes , D G

¼ X final

0.
Equilibrium structures do not dissipate any free energy, but dissipative structures
do (i.e., D G

<

<

0), as the name indicates (Prigogine 1977, 1980). In addition,
dissipative structures can lead to the organization of matter in space (e.g., the
flame of a candle) or in time (e.g., oscillating chemical concentrations in a test
tube) (Babloyantz 1986). Organisms are excellent examples of dissipative structures
(Prigogine 1977, 1980).
Though it had been known for a long time that living systems must obey the
same laws of thermodynamics that originated from the study of nonliving systems,
such as the steam engine invented in the 1700s, the first serious attempt to formulate
the theoretical connection between thermodynamics and biology seems to have
been made by I. Prigogine (1917-2003) and his groups at the Free University of
Brussels in Belgium and the University of Texas at Austin (Prigogine 1977, 1980;
Nicolis and Prigogine 1977; Kondepudi and Prigogine 1998; Kondepudi 2008).
Prigogine and his coworkers have established the concept that irreversible physico-
chemical processes occurring in far from equilibrium systems are necessary for any
constructive process, variously referred to as “self-organizing processes,” “self-
organization,” or “dissipative structures.” These and related terms are diagrammati-
cally represented in Fig. 2.1 .