Calvin cycle: it is a process by which plants turn the carbon dioxide present in the air into sugar, it is a part of the photosynthesis process.
The Calvin cycle has 3 stages:
1. Fixation
2. Reduction
3. Regeneration
1. Fixation: in this stage the carbon dioxide present in the air enters the chloroplast and reacts with a molecule called ribulose bisphosphate (RuBP). The enzyme RuBisCO helps to catalyze this reaction.
After the reaction 2 three-carbon compounds (called 3-PGA) are formed.
2. Reduction: in this stage the 3-PGA molecules are transformed into glyceraldehyde 3-phosphate (G3P), by using the energy stored in ATP and NADPH.
3. Regeneration: in this stage one of the G3P leaves the cycle to be used in the formation of carbohydrate molecules like glucose (C6H12O6). The remaining G3P molecules are used to regenerate RuBP to be used again in the next Calvin cycle.