Calvin-Benson metabolic cycle for carbon fixation in plants. This universal photosynthetic process,the reductive pentose phosphate cycle,is also called the Calvin cycle. It takes place in the stroma of chloroplasts in photosynthetic organisms. Carbon dioxide (CO2,lower left) goes through a series of reactions to produce the simple sugar sucrose (lower right). The chemicals shown are RuBP (ribulose-1,5-biphosphate),phosphoglyceric acid (PGA),glyceraldehyde-3-phosphate (PGAL),ATP (adenosine triphosphate),ADP (adenosine diphosphate),NADPH (nicotinamide adenine dinucleotide phosphate) and Pi (inorganic phosphate). Orange dots indicate the number of carbon atoms |