1. Light-Dependent Reactions:
* Location: Thylakoid membrane of chloroplasts
* Input: Light energy, water (H₂O)
* Output: ATP (energy carrier), NADPH (reducing agent), oxygen (O₂)
Key reactions:
* Photolysis of water: Water molecules are split using light energy, releasing electrons (e-), protons (H+), and oxygen gas (O₂).
* Electron transport chain: Electrons from water move through a series of electron carriers, releasing energy used to pump protons into the thylakoid lumen, creating a proton gradient.
* ATP synthesis: The proton gradient drives ATP synthase, which converts ADP and inorganic phosphate (Pi) into ATP.
* NADPH production: Electrons from the electron transport chain are used to reduce NADP+ to NADPH.
2. Light-Independent Reactions (Calvin Cycle):
* Location: Stroma of chloroplasts
* Input: Carbon dioxide (CO₂), ATP, NADPH
* Output: Glucose (C₆H₁₂O₆), ADP, NADP+
Key reactions:
* Carbon fixation: CO₂ is incorporated into an organic molecule, RuBP (ribulose bisphosphate), by the enzyme Rubisco.
* Reduction: The resulting molecule is reduced using ATP and NADPH, forming glucose.
* Regeneration: RuBP is regenerated from the remaining molecules to continue the cycle.
Overall Equation of Photosynthesis:
6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂
This equation summarizes the process of photosynthesis, where carbon dioxide and water are converted into glucose and oxygen using light energy.
