Reconsideration of the Photosynthetic Mechanism in Chlorella

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Abstract
No basic differences are found between the photosynthetic behavior of Chlorella and that of higher plants. However, the N content is 8-10%. The cell constituents are about half protein and half carbohydrate. In close approximation, all the products of photosynthesis result in cellular materials. In a growing culture, protein and carbohydrate syntheses must proceed at about equal rates. The rapid synthesis of proteins is borne out by studies of the assimilatory quotient as affected by the source of N supplied. The growing cells require protein and carbohydrate syntheses at about equal rates and these syntheses may result from photosynthesis or from oxidative assimilation of an organic substrate in the dark. It is reasonable to expect similarities in the pathways of the two modes of synthesis. It is suggested that in photosynthesis the photochemical product is some intermediate, not itself carbohydrate, which may be converted subsequently to carbohydrate or to protein by metabolic paths similar to those of heterotrophic forms. This hypothesis has apparent conflicts with other theories and exptl. data.