1. Light-dependent reactions:
* Light absorption: Pigments like chlorophyll capture light energy, primarily in the red and blue wavelengths.
* Electron transport chain: The captured light energy excites electrons within the chlorophyll molecule, initiating an electron transport chain. This chain releases energy, which is used to create ATP (adenosine triphosphate), an energy-carrying molecule.
* Water splitting: Water molecules are split, releasing oxygen as a byproduct and providing electrons to replace those lost from chlorophyll.
2. Light-independent reactions (Calvin cycle):
* Carbon fixation: Using the ATP and NADPH (another energy-carrying molecule) produced in the light-dependent reactions, the Calvin cycle takes in carbon dioxide from the atmosphere and converts it into glucose, a sugar molecule.
* Glucose synthesis: The cycle continues, ultimately generating glucose, which serves as a primary source of energy for the organism.
In summary, photosynthetic organisms harness light energy to drive a series of reactions that convert carbon dioxide and water into glucose and oxygen. This process is crucial for life on Earth, providing both food and oxygen for many organisms.
