Intelligent Design, the best explanation of Origins

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Intelligent Design, the best explanation of Origins » Molecular biology of the cell » Metabolism » Transformation of Energy to Maintain a Low Entropy State and Perform Work

Transformation of Energy to Maintain a Low Entropy State and Perform Work

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Transformation of Energy to Maintain a Low Entropy State and Perform Work

Maintenance of the low entropy state of living systems requires the persistent infusion of energy (Morowitz 1968), first, to enable the system to maintain its complex organization and resist dissipation toward randomness. The second requirement for an input of energy derives from the fact that living processes perform work by growing and retracting, moving through the environment, emitting energy, counteracting concentration gradients, transforming materials, erecting and breaking down structures, and other endogenous activities. While energy transformations are characteristic of all dynamic physical and chemical systems, energy flow in non-living systems tends to result in greater disorder among all elements of the system. Energy released through different stages of the rock and water cycles, for instance, generally erodes land and distributes water to increase the entropy of the total collection of water and land toward equilibrium (lower mountains, more dispersed water and soil). The energy transformations of living systems, on the other hand, serve primarily to harvest and store the levels of free energy necessary for maintaining the highly ordered structure of the organism and performing the work that living cells carry out. The net effect for living systems, in contrast to that for non-living systems, is to maintain and often increase order at local levels and on microscopic scales.

There are two consequences to the way in which life transforms energy. One is that much of the energy is used to create and sustain a level of complexity that supports emergent functions that in their totality exceed the sum of the parts of the system. A mountain may be structurally complex but its role in the rock cycle is not dependent on the detailed organization of its individual rocks and sediments. The mountain is in essence a simple conglomerate of its component parts. The function of a living organism, on the other hand, depends critically on precisely how it is put together. Its component parts function in a coordinated manner, to generate a complex array of emergent properties, both structurally and functionally. The generation and maintenance of this complexity is one of the primary uses of the energy that living systems transform. A second consequence of biological energy transformations is to create one or more additional microenvironments within the natural environment. The Eh (redox-potential), pH, solute composition, and structural complexity of the living cell is maintained at levels different from the extracellular environment because of the autonomous functions carried out by the cell, but not in the abiotic environment surrounding the cell. New environments can also be created on a larger scale by colony forming organisms such as stromatolites and corals, which can alter the topography of large amounts of habitat.

Life-induced changes can occur even on a planetary scale, such as the change in atmospheric oxygen composition brought about by oxygen-producing microbes on Earth, beginning with the emergence of photosynthesis as a uniquely biological form of energy transformation (Knoll 1999; Schopf 1994). This innovation enabled life to become autotrophic (manufacturer of its own food from the simple and abundant molecule, CO2) on a global scale. Thus, not only is the transformation of energy a characteristic of life, but so is the ability of life to alter conditions in the natural environment. Note the dual requirement of living systems: to resist an increase in entropy, and to perform work. Both requirements are essential for the definition of a living entity. Any fabrication or machine is, for the time being, at a lower state of entropy than, and in disequilibrium with, its environment. Indeed, such objects are known to exist on other worlds: the lifeless Huygens lander rests on Titan, and the surfaces of Mars and the Moon are littered with man-made objects. When a cell or organism can no longer maintain steady disequilibrium conditions it approaches equilibrium with its environment and therefore dies

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