where concA" concc D, and so on, are the concentrations of the several reactants in moles per liter. Here, also, the value of K^ is related to SG by Equation 4-3 (see also Table 4-1).
Because energies of activation are generally between 20 and 30 koil/mol, activated states practically never occur at physiological temperatures. High activation energies are thus barriers preventing spontaneous rearrangements of cellular-covalent bonds.
These barriers are enormously important. Life woidd be impossible if they did not exist, for all atoms would be in the state of least possible energy. There would be no wray to temporarily store energy for future work. On the other band, life would also be impossible if means were not found to selectively lower the activation energies of certain reactions. This also must happen if cell growth is to occur at a rate sufficiently fast so as not io be seriously impeded by random destructive forces, such as ionization or ultraviolet radiation.
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