PART II 

 STORAGE AND TRANSFER OF INFORMATION 



A CENTRAL issue in modern biology, which touches in some degree all branches 

 of that science, is the problem of species specificity and its relation to protein- 

 specificity and synthesis. The subject can be approached from many points of 

 view but the one adopted by the authors of the papers in Part II is to seek the 

 solution in terms of the properties of a communication system 



The justification for considering, from this point of view, a phenomenon 

 which looks, at first sight, to be purely biochemical lies in the recent discovery 

 that protein specificity is expressed as an exact order of amino acid residues. 

 If this is even substantially the case then it is germane to discuss such problems 

 in these terms. In fact, a number of current papers on protein synthesis and 

 specificity have recourse, at one point or another, to the language of information 

 theory. Since the specificity of proteins is thought to be coded in the exact order 

 of pairs of nucleotide bases in DNA, the relationship of DNA, RNA, and proteins 

 can be considered from aspects which are mathematical rather than purely bio- 

 chemical. 



Gamow was the first to notice these mathematical aspects. He and Ycas 

 pursue in this part some of the issues which they reveal. The influence one hopes 

 these considerations will have on the experimentalist is clear. Additional data 

 on the amino-acid residue sequences and other structural data for a large number 

 of proteins can be put to immediate practical use in solving for the protein code, 

 and therefore in understanding more about protein synthesis. Unfortunately, 

 mainly due to the lack of sufficient protein text, few definite answers can be given. 

 But it is possible to eliminate some past errors and to phrase the question in a 

 sharper fashion than before. 



The notion that an abstract quantity such as information is stored in the 

 genetic material and is transferred to proteins during their synthesis raises 

 immediate questions as to how this is done, how much is transferred, and how 

 this quantity is aff'ected by changing experimental conditions. These questions 

 are attacked from diff"erent analytical and experimental points of view by the 

 papers by Augenstine, by Mahler, Walter, Bulbenko and Allmann, and by 

 Koch and by Glinos. 



The information theoretic properties of communication systems of particular 

 concern to the papers in this part are the coding problem, the representation 

 theorem, and redundance. Each paper deals with issues of its own but in terms 

 of these ideas to a greater or lesser degree. It is in this way, among others, that 

 information theory may grow to be as useful to the biologist as thermodynamics 

 is to the chemist, whether his subject is clearly one in communication as is that 

 of Frishkopf and Rosenblith or somewhat less clearly that of protein specificity. 



H. P. Y. 



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