Here's a breakdown of the process:
1. Light-Dependent Reactions:
* Light Absorption: Chlorophyll, a green pigment found in chloroplasts, absorbs sunlight.
* Electron Excitation: The absorbed light energy excites electrons in chlorophyll.
* Electron Transport Chain: These excited electrons move through a series of protein complexes, releasing energy along the way.
* ATP and NADPH Production: The energy released is used to create ATP (adenosine triphosphate), the cell's energy currency, and NADPH (nicotinamide adenine dinucleotide phosphate), a reducing agent.
* Water Splitting: Water molecules are split, releasing oxygen as a byproduct.
2. Light-Independent Reactions (Calvin Cycle):
* Carbon Fixation: Carbon dioxide from the atmosphere is incorporated into an organic molecule called RuBP (ribulose bisphosphate).
* Reduction: The carbon dioxide is reduced, using the energy from ATP and NADPH, to form glucose, a simple sugar.
* Regeneration: RuBP is regenerated, allowing the cycle to continue.
Overall Equation of Photosynthesis:
6CO2 + 6H2O + light energy → C6H12O6 + 6O2
Where:
* CO2 = carbon dioxide
* H2O = water
* light energy = energy from sunlight
* C6H12O6 = glucose
* O2 = oxygen
Organisms that perform photosynthesis are called photoautotrophs, and they include plants, algae, and some bacteria. Photosynthesis is vital for life on Earth because it provides the energy source for most food chains and produces the oxygen we breathe.
