|This article does not cite any references or sources. (September 2008)|
Phototrophic prokaryotes are bacteria or archaea that obtain energy from light. Phototrophic prokaryotes may utilize a variety of carbon sources, depending on the metabolic pathways available to the bacterium. Most phototophic organisms are also autotrophs, obtaining carbon from atmospheric carbon dioxide in a process called photosynthesis. Among phototrophic bacteria the phylum Cyanobacteria are perhaps the most well kown, and probably the most important. Cyanobacteria are responsible both for the oxygenation of the earth in what is now known as the Great Oxygenation Event, and for the photosynthetic capabilities of plants wherein organelles known as Chloroplasts harvest light energy used by the plants in photosynthesis. Chloroplasts are revealed as descendants from cyanobacteria and it is theorized that cyanobacteria were adopted as organelles by early eukaryotes through endosymbiosis.
Cluster cells of Halobacterium