|Necessity, philosophy: different kinds of necessity are distinguished, differing in their strength. For example, physical, logical or metaphysical necessity. See also necessity de dicto, necessity de re.|
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Necessity/Monod: e.g. between the fact that the β-galactosidase hydrolyzes the β-galactosides and the fact that their biosynthesis is induced by the same substances, there is no chemically necessary relationship. Physiologically useful, chemically arbitrary. "free of force".
Necessity/Monod: For example, between the substrate of an allosteric enzyme and the ligands that stimulate or inhibit its activity, there is no chemically necessary relationship of structure or responsiveness.
The specific nature of the interactions is also independent of the structure of the ligands; it is determined exclusively by the proteins.
It follows that everything is possible!
An allosteric protein can produce a positive or negative interaction between substances without chemical affinity.
It may, therefore, subject any reaction of the influence of connections which are chemically alien and indifferent to this reaction.
Thus, the organism becomes an autonomous functional unit whose powers seem to transcend the laws of chemistry. The origin of this autonomy are the control proteins.
Zufall und Notwendigkeit Hamburg 1982