The Calvin cycle is an important metabolic pathway that takes place in the stroma section of the cell’s chloroplast. The main objective in the Calvin cycle is to turn carbon dioxide into a form of sugar. In the cycle, ATP and NADPH2 are used as an energy source. In the first step of the cycle, carbon fixation, carbon dioxide is converted into a five-carbon sugar called RuBP. Next, rubisco (an enzyme) catalyzes the five-carbon substance into a six-carbon sugar. Immediately after that the six-carbon sugar is split into two glyceraldehyde 3-phosphate (G3P). This acts as a precursor to glucose and other sugars. To complete the cycle, some of the G3P is converted back into RuBP. It takes nine ATP and 6 NADPH2 molecules to produce one G3P. Grass along with most other plants use this cycle for survival.