The simplified equation for the dark reaction (also known as the Calvin cycle) of photosynthesis is: ATP + NADPH + CO2 → ADP + NADP+ + Glucose.
Here's a breakdown of what this equation represents:
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ATP (Adenosine Triphosphate): This is an energy-carrying molecule produced during the light-dependent reactions of photosynthesis. It provides the energy needed to power the Calvin cycle.
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NADPH (Nicotinamide Adenine Dinucleotide Phosphate): This is another energy-carrying molecule also produced during the light-dependent reactions. It provides the reducing power (electrons) needed to fix carbon dioxide.
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CO2 (Carbon Dioxide): This is the source of carbon that is incorporated into glucose. Plants obtain carbon dioxide from the atmosphere.
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ADP (Adenosine Diphosphate): This is what ATP becomes after it releases its energy. It's then recycled back to the light-dependent reactions to be recharged into ATP.
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NADP+ (Nicotinamide Adenine Dinucleotide Phosphate): This is what NADPH becomes after it donates its electrons. It's also recycled back to the light-dependent reactions to be recharged into NADPH.
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Glucose (C6H12O6): This is a simple sugar that is the end product of the Calvin cycle. It serves as the plant's primary source of energy.
The dark reactions occur in the stroma of the chloroplast and are light-independent because they do not directly require light energy. However, they do require the ATP and NADPH produced during the light-dependent reactions, which are light-dependent. The Calvin cycle is a cyclical series of reactions that fix carbon dioxide, reduce it using the energy from ATP and NADPH, and regenerate the starting molecule so the cycle can continue.
