Chapter 11 - Thermodynamics and Biological Systems

Abstract

Systems may exhibit two different types of behavior: (1) the tendency toward maximum disorder, or (2) the spontaneous appearance of a high degree of organization in space, time, and/or function. The best examples of the latter are dissipative systems at nonequilibrium conditions, such as the Bénard cell, the tricarboxylic acid cycle, ecosystems, and living systems. As living systems grow and develop, a constant supply of energy is needed for reproduction and survival in changing conditions. Organized structures require a number of coupled metabolic reactions and transport processes that control the rate and timing of life processes. Biochemical reaction cyclic processes maintain the biological cell in nonequilibrium state by controlling the influx of reactants and efflux of products. Biological systems do not decay toward an equilibrium state, but instead increase in size, developing organized structures and complexity. An evolved and adapted biological system converts energy in an efficient manner for the transport of substances across a cell membrane, the synthesis and assembly of proteins, muscular contraction, reproduction, and survival. The source of energy is adenosine triphosphate, which is produced by oxidative phosphorylation in the inner membrane of the mitochondria.