Abstract
Radioisotopically labelled compounds (14CO2, 32P-phosphates, [2-14C]-acetate, L-[4, 5-3H]leucine, [6-3H]thymidine, [2-14C]thymine, [5-3H]-uridine and [2-14C]uracil) were fed for 1hr to synchronized Chlorella cells at various stages of the cell cycle, and uptake and incorporation of the tracers into DNA, RNA, and protein of algal cells were examined. They showed more or less characteristic patterns in the process studied. The three kinds of macromolecular cell constituents took up the radioactivities of all the compounds tested, except in the case of [6-3H]-thymidine, whose radioactivity was incorporated into DNA and protein but not into RNA. 14C of CO2 seemed to be specifically or preferentially incorporated into chloroplast macromolecules under photosynthesizing conditions.