BIOLOGICAL ORDER AND ENTROPY 



physical entropy is even more complicated. The study of the 

 functional order has revealed a very high degree of nonstructural, 

 functional coupling between the active units of a cell. And Linschitz 

 has proposed that this type of organization should also be taken 

 into account in the calculation of what he calls a "biological negen- 

 tropy." This is certainly a very pertinent suggestion. I would like to 

 illustrate this point by an example. As a result of an accident, one 

 nucleic base of the genetic material is sometimes replaced by another. 

 This alteration may cause the death of the organism. If, for example, 

 one given molecule of guanine in a given gene is replaced by a 

 molecule of adenine, the information, the structural negentropy of 

 the system, is the same. For the physicist, even if the mutation is 

 lethal, nothing has changed: the content in negentropy has remained 

 the same. But the mutation being lethal, the altered organism is now 

 unable to function normally and to reproduce. It has ceased to be 

 alive. As a consequence of the introduction' of the genetic material 

 of a virus, the negentropy of a cell/virus system is greater than the 

 negentropy of the normal, original, noninfected cell. But the in- 

 fected cell will die; that is, its information will be destroyed. 



The value of the negentropy obviously does not give a measure 

 of the efficiency of the system. The living organism is not only an 

 improbable system but a system fitted for certain functions. Low 

 probability and value are not synonymous. Brillouin has proposed 

 a generalized negentropy principle that would take into account 

 the value of the organization or information. This corresponds to a 

 radical development and a broad extension of the notion of entropy 

 and to something quite different from the classical physical concept. 



The biologist feels that the functional order is an essential part of 

 the living system. It is clear, however, that this functional order 

 cannot be measured in terms of entropy units, and is meaningless 

 from a purely thermodynamical point of view. And it happens, 

 as will be seen next, that the term "information" has for the biologist 

 a different sense than for the physicist. 



Remarks on "Genetic Information" 



The synthesis of a given specific protein is under the control of 

 nucleic acid. Nucleic acid therefore contains the blueprint for the 



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