Bacteriële fotosynthese

Oxygenic photosynthesis harnesses light energy to convert water and carbon dioxide into glucose and oxygen.

Oxygenic phototrophs, such as cyanobacteria and algae, use chlorophyll pigments embedded in their thylakoid membranes, which arise from the infolding of the plasma membrane.

Cyanobacteria organize these pigments into two photosystems: Photosystem I, P700, and Photosystem II, P680.

Photosystem II oxidizes water, releasing oxygen, protons, and electrons. The electrons move to pheophytin, then through plastoquinone to the cytochrome b6f complex.

Plastocyanin carries electrons to photosystem I, where light re-energizes them.

Excited electrons move to ferredoxin, then to ferredoxin-NADP⁺ reductase, which uses them to reduce NADP⁺ to NADPH.

The electron transport pumps protons across the membrane, generating a proton gradient that drives ATP synthase.

In some cases, electrons from photosystem I can return to the electron transport chain, generating additional ATP without producing NADPH or oxygen.