To: Brumar89 who wrote (39558 ) 7/25/2013 6:22:20 PM From: 2MAR$ Read Replies (1) | Respond to The Tobacco Mosaic Virus reconstituted by self-assembly. The reconstituted TMV thus not only comes back to ‘life’, it can even reproduce itself if placed on a tobacco leaf!8.7 We Owe Our Lives to the Hydrogen Bond . This bond is much weaker than the covalent bond, and yet strong enough to sustain self-assembled biological structures, enabling them to withstand the disintegrating influences of thermal fluctuations and other perturbations. Hydrogen bonding, and the associated hydrophobic interaction, has the right kind of strength to enable superstructures to self-assemble without the need for irreversible chemical reactions. There is a strong element of reversibility associated with these weak interactions, enabling the spontaneous making and breaking of assemblies until the lowest-free-energy configuration has been attained.8.8 Self-Organization and in the interaction patterns among them. The build up of this information involves a succession of stages: molecular recognition; self-assembly; self-organization; and chemical adaptation and evolution. We have already considered the first two. Let us now focus on self-organization. Smart Structures: Blurring the Distinction between the Living and the Nonliving (2007).A laser is a self-organized system. Under properly engineered conditions, photons spontaneously group themselves into a configuration in which they all move in phase, resulting in a powerful laser beam. A hurricane is a self-organized system. The steady influx of energy from the Sun draws water from the oceans, as well as drives the winds. Mild tropical winds may grow into an organized configuration of a hurricane when some critical threshold is crossed. A living cell is a self-organized system, which organizes itself all the time, depending on the environment. An economy is a self-organizing system. The demand for goods and services, as also the demand for labour, constantly organizes the economy in a spontaneous way, without any central controlling authority. 8.9 Chemical Adaptation and Evolution chemical adaptation . Now suppose this set of conditions changes . This is very likely, in fact inevitable, because we are dealing with an open system. A further round of self-organization must occur, governed as always by the second law of thermodynamics. This is chemical evolution . Moreover, the set of changing conditions, i.e. the changing environment experienced by the molecules, need not necessarily be that external to the set of molecules. Even internal changes in the molecular system present a changed environment to every member of the set. And molecular configurations are changing all the time. Thus, chemical adaptation and evolution occurs in an open system of molecules (including our ecosystem) all the time.autocatalysis as a mechanism for molecular selection. I shall consider autocatalysis in the next article.
