What is the role of NADPH in the Calvin Cycle?

In the Calvin Cycle, NADPH plays a crucial role as a reducing agent that provides the necessary reducing power for the conversion of carbon dioxide and ribulose bisphosphate into glucose and other carbohydrates. Specifically, NADPH donates high-energy electrons, which contribute to the formation of sugars. This process occurs in the light-independent reactions of photosynthesis, where the energy stored during the light-dependent reactions in the form of NADPH is utilized to drive the synthesis of glucose from carbon sources.

Unlike ATP, which directly supplies energy for enzymatic reactions, NADPH primarily serves in the reduction reactions, enabling the conversion of glycerate into carbohydrates. This makes NADPH vital for sustaining the cycle and ensuring that the energy-rich products necessary for plant growth and metabolism are adequately produced. The specific involvement of NADPH means that it is integral to the overall efficiency and functioning of the Calvin Cycle, reinforcing its importance in photosynthesis.