What is the primary function of the Calvin cycle?

The primary function of the Calvin cycle is to fix carbon dioxide into glucose. This process occurs in the stroma of chloroplasts where carbon dioxide is incorporated into organic molecules through a series of enzymatic reactions. The main substrate for this process is ribulose bisphosphate (RuBP), which reacts with carbon dioxide to ultimately produce glyceraldehyde-3-phosphate (G3P), a three-carbon sugar. Through subsequent reactions, G3P is used to generate glucose and other carbohydrates, which serve as essential energy sources for the plant and, ultimately, for other organisms that consume plants.

This cycle is crucial because it synthesizes organic compounds from inorganic carbon (CO2) using the energy derived from ATP and NADPH produced during the light-dependent reactions of photosynthesis. By converting carbon dioxide into glucose, the Calvin cycle plays a fundamental role in the overall process of photosynthesis, enabling plants to store energy in a stable form.