| | Hess, B.; Markus, M.Order and chaos in biochemistry. Trends Biochem. Sci. 12:45-48, 1987
Schrödinger, E.What Is Life? Mind and Matter. Cambridge, UK: Cambridge University Press, 1969. |
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|  | Introduction
Cells must obey the laws of physics and chemistry. The rules of mechanics and of the conversion of one form of energy to another apply just as much to a cell as to a steam engine. There are, however, puzzling features of a cell that, at first sight, seem to place it in a special category. It is common experience that things left to themselves eventually become disordered: buildings crumble, dead organisms become oxidized, and so on. This general tendency is expressed in the second law of thermodynamics, which states that the degree of disorder in the universe (or in any isolated system in the universe) can only increase.
The puzzle is that living organisms maintain, at every level, a very high degree of order; and as they feed, develop, and grow, they appear to create this order out of raw materials that lack it. Order is strikingly apparent in large structures such as a butterfly wing or an octopus eye, in subcellular structures such as a mitochondrion or a cilium, and in the shape and arrangement of molecules from which these structures are built. The constituent atoms have been captured, ultimately, from a relatively disorganized state in the environment and locked together into a precise structure. Even a nongrowing cell requires constant ordering processes for survival since all of its organized structures are subject to spontaneous accidents and must be repaired continually. How is this possible thermodynamically? The answer is that the cell draws in fuel from its environment and releases heat as a waste product. The cell is therefore not an isolated system in the thermodynamic sense.
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