PSI (Photosystem I)

Photosystem I (PSI) is a crucial protein complex in the process of photosynthesis, primarily found in the chloroplasts of plant cells. It captures light energy and uses it to transfer electrons through a series of reactions, ultimately helping produce energy-rich molecules like NADPH. PSI works closely with Photosystem II, forming part of the light-dependent reactions that convert sunlight into chemical energy. This energy is then used in the Calvin cycle to synthesize sugars, fueling plant growth and providing energy for nearly all life forms.