Final answer:
The three main steps of the Calvin cycle include fixation, where CO2 is attached to RuBP by RuBisCO; reduction, where ATP and NADPH convert three-carbon compounds to G3P; and regeneration, where RuBP is regenerated and carbohydrates are synthesized.
Step-by-step explanation:
The Light-Independent Reactions of Photosynthesis
The three main steps of light-independent reactions, often referred to as the Calvin cycle, include fixation, reduction, and regeneration. During the fixation stage, the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) facilitates the attachment of carbon dioxide (CO2) to ribulose bisphosphate (RuBP), forming a six-carbon compound that soon splits into two three-carbon compounds. In the reduction step, ATP and NADPH, produced by the light-dependent reactions, are used to convert these three-carbon compounds into a more energy-rich molecule, G3P (glyceraldehyde-3-phosphate). Finally, in the regeneration phase, some of the G3P molecules are used to regenerate RuBP, enabling the cycle to continue, while the rest serve as building blocks for synthesizing glucose and other carbohydrates.