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In general, photosynthesis in cyanobacteria uses water as an electron donor and produces oxygen as a byproduct, though some may also use hydrogen sulfide [80] a process which occurs among other photosynthetic bacteria such as the purple sulfur bacteria. Carbon dioxide is reduced to form carbohydrates via the Calvin cycle. [81]
The biochemical capacity to use water as the source for electrons in photosynthesis evolved once, in a common ancestor of extant cyanobacteria (formerly called blue-green algae). The geological record indicates that this transforming event took place early in Earth's history, at least 2450–2320 million years ago (Ma), and, it is speculated ...
Cyanobacteria is the only prokaryotic group that performs oxygenic photosynthesis. Anoxygenic photosynthetic bacteria use PSI- and PSII-like photosystems, which are pigment protein complexes for capturing light. [5] Both of these photosystems use bacteriochlorophyll. There are multiple hypotheses for how oxygenic photosynthesis evolved.
is, in essence, the same as the electron transport chain in chloroplasts. The mobile water-soluble electron carrier is cytochrome c 6 in cyanobacteria, having been replaced by plastocyanin in plants. [8] Cyanobacteria can also synthesize ATP by oxidative phosphorylation, in the manner of other bacteria. The electron transport chain is
In the reaction center of PSII of plants and cyanobacteria, the light energy is used to split water into oxygen, protons, and electrons. The protons will be used in proton pumping to fuel the ATP synthase at the end of an electron transport chain. A majority of the reactions occur at the D1 and D2 subunits of PSII.
Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is located in the thylakoid membrane of plants , algae , and cyanobacteria .
However, most marine primary production comes from organisms which use photosynthesis on the carbon dioxide dissolved in the water. This process uses energy from sunlight to convert water and carbon dioxide [ 4 ] : 186–187 into sugars that can be used both as a source of chemical energy and of organic molecules that are used in the structural ...
Cyanobacteria turn energy from the sun into chemical energy through oxygenic photosynthesis. Their light-harvesting complex that captures the photons usually includes the pigments chlorophyll a and phycocyanin. A cyanobacterium's typical blue-green color is a result of the combination of these two pigments.