PhotosyntheseKette

PhotosyntheseKette is a pedagogical term used to describe the sequential chain of biochemical steps by which light energy is converted into chemical energy and used for carbon fixation in photosynthetic organisms. It encompasses two interconnected phases—the light-dependent reactions and the Calvin cycle—typically occurring in chloroplasts of plants and algae, and in similar membrane systems in some bacteria.

In the light-dependent reactions, chlorophyll and other pigments absorb light, driving the splitting of water, releasing oxygen, and transferring electrons through an electron transport chain that pumps protons across the thylakoid membrane. The resulting proton motive force powers ATP synthase to produce ATP, while electrons are transferred to NADP+, forming NADPH. These energy-rich carriers then feed into the next phase of the photosynthesis process.

The Calvin cycle, or the light-independent phase, uses ATP and NADPH to fix carbon dioxide into organic molecules. Through a series of enzymatic steps initiated by RuBisCO, CO2 is converted to 3-phosphoglycerate and ultimately to glyceraldehyde-3-phosphate, which can be used to synthesize sugars and regenerate the starting compound RuBP. The cycle operates repeatedly to build carbohydrates from CO2.

The term emphasizes the dependency and order of reactions, portraying photosynthesis as a continuous chain of energy capture, conversion, and carbon assimilation. It is widely used as a didactic construct and is not a formal term in current scientific nomenclature. The concept underpins understanding of plant physiology, ecological productivity, and bio-inspired approaches such as artificial photosynthesis.