![]() Their photosynthetic electron transport shares the same compartment as the components of respiratory electron transport. They also share an archaeal property, the ability to reduce elemental sulfur by anaerobic respiration in the dark. In anaerobic conditions, they are also able to use only PS I-cyclic photophosphorylation-with electron donors other than water (for example hydrogen sulfide), in the same way as the purple photosynthetic bacteria. The water-oxidizing photosynthesis is accomplished by coupling the activity of photosystem (PS) II and I (Z-scheme). Many cyanobacteria are able to reduce ambient levels of nitrogen and carbon dioxide under aerobic conditions, a fact that may be responsible for their evolutionary and ecological success. In most forms the photosynthetic machinery is embedded into folds of the cell membrane, called thylakoids.īecause of their ability to fix nitrogen in aerobic conditions they are often found in symbiontic partnerships with a number of other groups of organisms, including but not limited to fungi (lichens), corals, pteridophytes (Azolla), and angiosperms (Gunnera). Carbon dioxide is reduced to form carbohydrates via the Calvin cycle. Photosynthesis in cyanobacteria generally uses water as an electron donor and produces oxygen as a by-product, though some species may also use hydrogen sulfide as occurs among other photosynthetic bacteria. Cyanobacteria get their color from the bluish pigment phycocyanin, which they use to capture light for photosynthesis. As with any prokaryotic organism, cyanobacter does not show nuclei nor internal membranes many cyanobacter species have folds on their external membranes which function in photosynthesis. PHOTOSYNTHESIS AND OTHER METABOLIC PROCESSESĬyanobacteria use the energy of sunlight to drive photosynthesis, a process where the energy of light is used to split water molecules into oxygen, protons, and electrons. Cyanobacteria can be helpful in agriculture as they have the capability to fix atmospheric nitrogen to soil. Figure: Cyanobacteria: Cyanobacteria, also known as blue-green bacteria, blue-green algae, and Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis Figure: Blue-green algae cultured in specific media: Cyanobacteria cultured in specific media. These molecules can be absorbed by plants and converted into protein and nucleic acids. Heterocyst-forming species are specialized for nitrogen fixation and are able to bind nitrogen gas to ammonia (NH3), nitrites (NO−2) or nitrates (NO−3). Heterocysts may also form under the appropriate environmental conditions (anoxic) when fixed nitrogen is scarce. Thick-walled heterocysts, which contain the enzyme nitrogenase, vital for nitrogen fixation.Akinetes, the climate-resistant spores that may form when environmental conditions become harsh.Vegetative cells, the normal, photosynthetic cells that are formed under favorable growing conditions.Some filamentous colonies show the ability to differentiate into several different cell types, including: Colonies may form filaments, sheets, or even hollow balls. ![]() Cyanobacteria include unicellular and colonial species. The association of toxicity with such blooms has frequently led to the closure of recreational waters when blooms are observed. These can have the appearance of blue-green paint or scum. Aquatic cyanobacteria are probably best known for the extensive and visible blooms that can form in both freshwater and the marine environment. PHOTOSYNTHESIS AND OTHER METABOLIC PROCESSESĬyanobacteria can be found in almost every terrestrial and aquatic habitat. ![]()
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