fotosintez

Fotosintez is the biochemical process by which light energy is converted into chemical energy, allowing photosynthetic organisms to synthesize organic compounds from carbon dioxide and water while releasing oxygen in most cases. It occurs primarily in chloroplasts of plants and algae, and in some bacteria, with the specific mechanisms varying across groups.

In oxygenic photosynthesis, the process is traditionally described as occurring in two stages. The light-dependent reactions take place in the thylakoid membranes, where light energy is captured by chlorophyll and other pigments to produce ATP and NADPH and to split water, releasing oxygen. The subsequent Calvin cycle, or dark reactions, occurs in the stroma and uses ATP and NADPH to fix carbon dioxide into sugars, ultimately forming compounds such as glucose.

The overall simplified chemical equation is: 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2. In addition to the standard C3 pathway present in many plants, some species utilize C4 or CAM pathways to concentrate carbon dioxide and reduce photorespiration under hot or dry conditions.

Fotosintez is fundamental for life on Earth because it is the primary source of organic matter for almost all organisms and it is responsible for the release of most atmospheric oxygen. The rate of fotosintez is influenced by factors such as light intensity and quality, carbon dioxide concentration, temperature, water availability, and the presence of pigments and enzymes that govern the process.