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Photosynthetic Organisms - Plants, Algae, Cyanobacteria

All photosynthetic plants, algae, and cyanobacteria contain ..

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Cyanobacteria | Cyanobacteria | Photosynthesis

Although there are some differences between oxygenic photosynthesis in plants, algae and cyanobacteria, the overall process is quite similar in these organisms. WHERE DOES PHOTOSYNTHESIS OCCUR?

Photosynthesis in cyanobacteria generally uses water as an electron donor and produces ..

Anaerobic photosynthetic bacteria is a group of bacteria that do not produce oxygen during photosynthesis and only photosynthesize in environments that are devoid of oxygen. These bacteria use carbon dioxide and a substrate such as hydrogen sulfide to make carbohydrates. They have bacteriochlorophylls and other photosynthetic pigments that are similar to the chlorophylls used by higher plants. But, in contrast to higher plants, algae and cyanobacteria, the anaerobic photosynthetic bacteria have just one photosystem that is similar to PS-I. These bacteria likely represent a very ancient photosynthetic microbe.

Introduction to the Cyanobacteria - UCMP

The ability of cyanobacteria to perform oxygenic photosynthesis is thought to have converted the early reducing atmosphere into an oxidizing one, which dramatically changed the composition of life forms on Earth by stimulating biodiversity and leading to the near-extinction of oxygen-intolerant organisms. According to endosymbiotic theory, chloroplasts in plants and eukaryotic algae have evolved from cyanobacterial ancestors via endosymbiosis.

A number of photosynthetic bacteria are known. One example are the bacteria of the genus . These bacteria were formerly called the blue-green algae and were once considered members of the plant kingdom. However, unlike the true algae, cyanobacteria are prokaryotes, in that their DNA is not sequestered within a nucleus . Like higher plants, they have chlorophyll-a as a photosynthetic pigment, two photosystems (PS-I and PS-II), and the same overall equation for photosynthesis (equation 1). Cyanobacteria differ from higher plants in that they have additional photosynthetic pigments, referred to as phycobilins. Phycobilins absorb different wavelengths of light than chlorophyll and thus increase the wavelength range, which can drive photosynthesis. Phycobilins are also present in the Rhodophyte algae, suggesting a possible evolutionary relationship between these two groups.

PHOTOSYNTHETIC CYTOCHROMES c IN CYANOBACTERIA…

cyanobacteria or blue-green algae, photosynthetic that contain chlorophyll. For many years they were classified in the plant kingdom along with , but discoveries made possible by the electron microscope and new biochemical techniques have shown them to be prokaryotes more similar to bacteria than to plants, and they are now placed in the kingdom . Cyanobacteria are familiar to many as a component of pond scum. Despite their name, different species can be red, brown, or yellow; blooms (dense masses on the surface of a body of water) of a red species are said to have given the Red Sea its name. Nitrogen-fixing cyanobacteria need only nitrogen and carbon dioxide to live.

Cyanobacteria include unicellular and colonial species. Colonies may form filaments, sheets or even hollow balls. Some filamentous colonies show the ability to differentiate into several different cell types: vegetative cells, the normal, photosynthetic cells that are formed under favorable growing conditions; akinetes, the climate-resistant spores that may form when environmental conditions become harsh; and thick-walled heterocysts, which contain the enzyme nitrogenase, vital for nitrogen fixation. Heterocysts may also form under the appropriate environmental conditions (anoxic) when fixed nitrogen is scarce. Heterocyst-forming species are specialized for nitrogen fixation and are able to fix nitrogen gas into ammonia (NH3), nitrites (NO−2) or nitrates (NO−3) which can be absorbed by plants and converted to protein and nucleic acids (atmospheric nitrogen is not bioavailable to plants).

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  • This is known as anoxygenic photosynthesis

    The cyanobacteria, which carry out a process of oxygenic photosynthesis common to that found in green plants and ..

  • Cyanobacteria perform photosynthesis using water ..

    Plants, algae, as well as cyanobacteria are responsible for a major part of photosynthesis in oceans.

  • What Is Photosynthesis? From Light Energy to Chemical …

    Photosynthesis - Wikipedia

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Plant Life Process - Photosynthesis - Learn to Discover

No other group of microbes participates in as many symbioses as cyanobacteria, including extra- or intracellular relationships with plants,fungi, and animals. This phenomenon, coupled with the plantlike photosynthesis of cyanobacteria, suggests that cyanobacteria were the progenitors of chloroplasts . Endosymbiotic theory holds that ancestral eukaryotic cells engulfed the ancient cyanobacteria that evolved into modern plastids. Better candidates may be prochlorophytes, oxygenic photosynthetic bacteria that contain chlorophyll and and form an evolutionarily related group with cyanobacteria and plastids.

Schematic of photosynthesis in plants

Many species of cyanobacteria fix atmospheric dinitrogen (N2) into ammonia (NH3) using nitrogenase, an enzyme that is particularly sensitive to the presence of oxygen. In filamentous cyanobacteria, such as and , certain cells differentiate into heterocysts (thick-walled cells that do not photosynthesize), in which nitrogen fixation occurs under reduced oxygen concentrations. Cyanobacterial nitrogen fixation produces bioavailable nitrogen compounds that are important in nitrogen-limited aquatic ecosystems and plays an important role in global nitrogen cycling.

The carbohydrates produced are stored in or used by the plant

A distinguishing feature of cyanobacteria is their photosynthetic pigment content. In addition to chlorophyll , cyanobacterial thylakoids include phycobilin-protein complexes (phycobilisomes) containing mixtures of phycocyanin, phycoerythrin, and allophycocyanin, which give cyanobacteria their characteristic blue-green coloration. Phycobilisomes harvest light at wavelengths (500 to 650 nanometers ) not absorbed by chlorophylls. Mostcyanobacteria perform oxygenic photosynthesis like higher plants. A few species perform anoxygenic photosynthesis, removing electrons from hydrogen sulfide (H2 S) instead of water (H2 O). There is a general dependence on carbon dioxide as a carbon source, although some cyanobacteria can live heterotrophically by absorbing organic molecules. The reductive pentose phosphate pathway predominates for carbon assimilation, as cyanobacteria have an incomplete tricarboxylic acid (Krebs) cycle.

Cyanobacterial-based approaches to improving photosynthesis in ..

Cyanobacteria are arguably the most successful group of microorganisms on earth. They are the most genetically diverse; they occupy a broad range of habitats across all latitudes, widespread in freshwater, marine and terrestrial ecosystems, and they are found in the most extreme niches such as hot springs, salt works, and hypersaline bays. Photoautotrophic, oxygen-producing cyanobacteria created the conditions in the planet's early atmosphere that directed the evolution of aerobic metabolism and eukarotic photosynthesis. Cyanobacteria fulfill vital ecological functions in the world's oceans, being important contributors to global carbon and nitrogen budgets.

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