556 



LIGHT AND LIFE 



I 



o 



z 



4 



T23i-5 "■■'■'■" '■ 



30" L 



Cg .OOOUMFMN 



Jl 



PH0SPH06LYCERATE 



^K^^iP 



OIHYOHOXYACETONE 

 PHOSPHATE 





MONWHOSPHATES 

 (GLUCOSE. FaiCTOSE) 



^^P 



DIPHOSPHATES 

 (FRUCTOSE. R18UL0«) 



f 



PMENOt/^tATtR- 



Fig. 28. Radioautogiaph of a chiomatogram showing products of photosynthetic 

 C'Oo assimilation by illuminated chloroplasts supplied with 0.001 micromoles FMN 

 (Trebst, Losada, and Arnon, 151). 



If, in the early periods of evolution of life forms, organic compounds 

 were abundant and the earth's atmosphere was a reducing one (117, 

 107), then the beginning of photosynthesis may be viewed as an 

 emergence of a porphyrin that gave rise to chlorophyll and permitted 

 the cell to use lor metabolic pmposes the energy in the visible spec- 

 trum of sunlight. This j)rimitive photosynthesis consisted only of 

 anaerobic cyclic photophosphorylation. No oxygen was evolved and 

 no reduction of COo was essential, since our premise is that the en- 

 vironment contained preformed carbon compoinids. This primitive 

 type of photosynthesis is exemplified today by the already discussed 

 photoassimilation of acetate by the obligate phototrophic anaerobe, 

 Chromaliwn (97) . 



The harnessing of light energy for the synthesis of ATP was an 

 event of supreme im))()rian(C to tlic (cll. It jirovidcd the cell, in an 



