Mechanism of photosynthesis

The overall chemical equation for photosynthesis is:

6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂

This process occurs in two main stages:

1. Light-Dependent Reactions:

   • These reactions take place in the thylakoid membranes of chloroplasts.
   • Chlorophyll and other pigments absorb light energy.
   • This energy is used to split water molecules (photolysis), releasing oxygen (O₂), protons (H⁺), and electrons.
   • The electrons move through an electron transport chain, generating ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are energy-carrying molecules.

2. Light-Independent Reactions (Calvin Cycle):

   • These reactions occur in the stroma of chloroplasts and do not directly require light.
   • ATP and NADPH produced during the light-dependent reactions are used to convert carbon dioxide (CO₂) from the atmosphere into glucose (C₆H₁₂O₆).
   • This process involves a series of enzyme-catalyzed reactions, where CO₂ is "fixed" and reduced to form sugars.