The Origin of 

 Specific Proteins 



Clement L. Marker t 



Department of Biology 

 Johns Hopkins University, Baltimore, Maryland 



We are all aware of the fact that every field of hiology, including 

 molecular hiology, contributes in some degree to our appreciation of 

 biological diversity. Underlying the obvious diversity of living organ- 

 isms is a fundamental uniqueness in the molecular composition of 

 each individual. This uniqueness is based upon characteristic propor- 

 tions of small molecules and, even more important, upon the specific 

 structures of numerous macromolecules that compose essential parts 

 of the metabolic machinery. Of all these macromolecules, perhaps the 

 widest range of diversity is found in the proteins. The only other class 

 of molecules of nearly equal significance is the nucleic acids — the raw 

 material of molecular genetics. But even the nucleic acids are, in a 

 fundamental sense, recognized principally through the proteins which 

 they control. Just as nucleic acids have occupied the attention of 

 geneticists, so have the properties and activities of proteins been at 

 the focus of much of the research in biochemistry. Tbe extraordinary 

 advances in each of these two fields, genetics and biochemistry, and 

 the remarkably fruitful collaboration between them in the study of 



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