CHAPTER 7 



Nucleic Acids as Carriers of Biological Information"^ 



1. IS THERE A HIERARCHY OF CELLULAR CONSTITUENTS? 



Our time is probably the first in which mythology has penetrated 

 to the molecular level. I read, for instance, in a recent article by 

 a very distinguished biologist: 



". . . In the early phases of the molecular stage of evolution, only simple 

 molecules were formed . . . Later more complex molecules, such as 

 amino acids and perhaps simple peptides, were formed. 



"In the more advanced phases of this period it is believed that there 

 appeared a molecule with two entirely new properties: the ability system- 

 atically to direct the formation of copies of itself from an array of 

 simpler building blocks, and the property of acquiring new chemical 

 configurations without loss of ability to reproduce. These properties, self- 

 duplication and mutation, are characteristic of all living systems and 

 they may therefore be said to provide an objective basis for defining the 

 living state. 



"Evidence is accumulating that the nucleic acids of present-day 

 organisms possess these two properties, and it is perhaps no longer useless 

 to speculate that the first "living" molecule might have been a simple 

 nucleic acid, perhaps protected by an associated simple protein . . ." 



Thus, what started cosmically with beautiful and profound 

 legends has come down to a so-called "macromolecule". If poetry 

 has suffered, precision has not gained. For we may ask whether 

 a model that merely provides for one cell constituent continually 

 to make itself can teach us much about life and its origins. We 

 may also ask whether the postulation of a hierarchy of cellular 

 constituents, in which the nucleic acids are elevated to a patriar- 

 chal role in the creation of living matter, is justified. I believe 



* Reprinted with permission from "The Origin of Life on the Earth", 

 I.U.B. Symposium Series, vol. 1, Pergamon Press, London, 1959, p. 297. 



