288 IV. THE PRINCIPLES OF LIFE PHENOMENA 



thesis of the protein might occur extremely slowly, so that there 

 would be no significant flow of energy. In this connection, it should 

 be realized that bacteria can, in general, make use of carbon dioxide 

 for their growth regardless of their lack of chlorophyll. 



Even before proteins which were synthesized in the primitive 

 ocean could form polymerization product capable of acting as typical 

 assimilase, carbon dioxide and some N-compounds like ammonia might 

 be condensed into protein molecules or amino acids by the sun energy. 

 The first proteins might be synthesized in this way, but the primeval 

 organisms, entirely disregarding such a synthesizing process, would 

 utilize the preexisted proteins, which had been already produced by 

 such a tedious way, just as the viruses utilize the protoplasm proteins; 

 however, as they evolved higher and higher and the protein structure 

 became complicated and advanced, the synthesyzing mechanism being 

 gradually arranged until highly differentiated enz^^me system, such 

 as chlorophyll, were developed with the manifestation of evident flow 

 of the energy and substances. 



The organisms appearing to be primitive secondary ones, such as 

 lower fungi and some protozoa, can produce chlorophyll to perform 

 free-living despite their extreme primitiveness. This may be explained 

 by assuming that these organisms have evolved from viruses which 

 were parasitic on higher plants containing chlorophyll, succeeding to 

 the highly developed enzyme system of the host, that is, chlorophyll, 

 so that they might be able to accomplish fifee-living in utilizing the 

 sun energy by means of chlorophyll despite of their most primitive 

 nature. Some bacteria also can live independently of their host, sug- 

 gesting that they might likewise obtain the enzyme system to utilize 

 carbon dioxide by transfer from the host. 



2. Nucleic Acid as Energy Donor 



The incorporation of various amino acids into protein may require 

 considerable amounts of energy, the majority of which may be pro- 

 duced by glycolysis whereby sugar is decomposed with the produ- 

 ction of energy. The energy, however, is apparently not given directly 

 in the form of heat, but it is preserved in the so-called energy-rich 

 phosphate bonds which will be decomposed in case of necessary to 

 liberate the energy. Most available energy-rich phosphate bonds are 

 believed to be involved in adenosine triphosphate (ATP) which is one 

 of the components of nucleic acids. 



This may be regarded as one of the reasons why the cell prolife- 

 ration is always connected with the increase in nucleic acid. The 



