- All the reactions of photosynthesis that are not directly dependent upon light are known as the dark reactions.
- The dark reactions occur when there is light or not.The dark reactions occur in the part of the chloroplast known as the stroma.
- The purpose of the dark reactions is to take the energy from ATP and energized electrons and hydrogen ions from NADPH and add them to CO2 to make glucose or sugar.
- The dark reaction occurs in the stroma of the chloroplast. This reaction is called carbon fixation or the Calvin cycle. In this reaction, carbon dioxide makes sugar using ATP and NADPH.
- Carbon dioxide is combined with a 5-carbon sugar to form a 6-carbon sugar. The 6-carbon sugar is broken into two sugar molecules, glucose and fructose.
- Equation: ATP + NADPH + CO2 ---> ADP + NADP + glucose