Fotossüntees

Fotossüntees is the fundamental biological process by which green plants, algae, and some bacteria convert light energy into chemical energy. This chemical energy is stored in the form of glucose, a sugar molecule, which serves as the organism's food source. The process primarily occurs in specialized organelles called chloroplasts, which contain chlorophyll, the green pigment that absorbs sunlight.

The overall chemical equation for photosynthesis is widely known: 6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2. This indicates that carbon dioxide from the atmosphere and water absorbed from the soil are the raw materials. Light energy is the driving force, and the products are glucose (sugar) and oxygen. Oxygen is released as a byproduct into the atmosphere, making photosynthesis crucial for most life on Earth, as it replenishes the oxygen we breathe.

Photosynthesis can be broadly divided into two stages: the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle). The light-dependent reactions, which take place in the thylakoid membranes of chloroplasts, capture light energy and use it to split water molecules, releasing oxygen and producing energy-carrying molecules like ATP and NADPH. The light-independent reactions, occurring in the stroma of chloroplasts, utilize the ATP and NADPH generated in the first stage to fix carbon dioxide from the atmosphere into glucose.

This remarkable process underpins the food chains of nearly all ecosystems, as the energy captured by photosynthetic organisms is transferred to herbivores that consume them, and then to carnivores that consume the herbivores. Beyond providing food, photosynthesis is also responsible for regulating atmospheric carbon dioxide levels.