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Phototrophic Bacteria
Phototrophs () are organisms that carry out photon capture to produce complex organic compounds (e.g. carbohydrates) and acquire energy. They use the energy from light to carry out various cellular metabolic processes. It is a common misconception that phototrophs are obligatorily photosynthetic. Many, but not all, phototrophs often photosynthesize: they anabolically convert carbon dioxide into organic material to be utilized structurally, functionally, or as a source for later catabolic processes (e.g. in the form of starches, sugars and fats). All phototrophs either use electron transport chains or direct proton pumping to establish an electrochemical gradient which is utilized by ATP synthase, to provide the molecular energy currency for the cell. Phototrophs can be either autotrophs or heterotrophs. If their electron and hydrogen donors are inorganic compounds (e.g. , as in some purple sulfur bacteria, or , as in some green sulfur bacteria) they can be also called lithotro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tropism
A tropism is a biological phenomenon, indicating growth or turning movement of a biological organism, usually a plant, in response to an environmental stimulus. In tropisms, this response is dependent on the direction of the stimulus (as opposed to nastic movements which are non-directional responses). Tropisms are usually named for the stimulus involved (for example, a phototropism is a reaction to sunlight). Tropisms occur in three sequential steps. First, there is a sensation to a stimulus. Next, signal transduction occurs. And finally, the directional growth response occurs. Tropisms are typically associated with plants (although not necessarily restricted to them). Where an organism is capable of directed physical movement (motility), movement or activity in response to a specific stimulus is more likely to be regarded by behaviorists as a ''taxis'' (directional response) or a '' kinesis'' (non-directional response). The Cholodny–Went model, proposed in 1927, is an ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterotroph
A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but not producers. Living organisms that are heterotrophic include all animals and fungi, some bacteria and protists, and many parasitic plants. The term heterotroph arose in microbiology in 1946 as part of a classification of microorganisms based on their type of nutrition. The term is now used in many fields, such as ecology in describing the food chain. Heterotrophs may be subdivided according to their energy source. If the heterotroph uses chemical energy, it is a chemoheterotroph (e.g., humans and mushrooms). If it uses light for energy, then it is a photoheterotroph (e.g., green non-sulfur bacteria). Heterotrophs represent one of the two mechanisms of nutrition (trophic levels), the other being autotrophs (''auto'' = self, ''troph'' = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Donor
In chemistry, an electron donor is a chemical entity that donates electrons to another compound. It is a reducing agent that, by virtue of its donating electrons, is itself oxidized in the process. Typical reducing agents undergo permanent chemical alteration through covalent or ionic reaction chemistry. This results in the complete and irreversible transfer of one or more electrons. In many chemical circumstances, however, the transfer of electronic charge to an electron acceptor may be only fractional, meaning an electron is not completely transferred, but results in an electron resonance between the donor and acceptor. This leads to the formation of charge transfer complexes in which the components largely retain their chemical identities. The electron donating power of a donor molecule is measured by its ionization potential which is the energy required to remove an electron from the highest occupied molecular orbital (HOMO). The overall energy balance (ΔE), i.e., energ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. There are two classes of redox reactions: * ''Electron-transfer'' – Only one (usually) electron flows from the reducing agent to the oxidant. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * ''Atom transfer'' – An atom transfers from one substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously the oxidation state of oxygen decreases as it accepts electrons released by the iron. Although oxidation reactions are commonly associated with the formation of oxides, other chemical species can serve the same function. In hydrogenation, C=C (and other) bonds ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemotroph
A Chemotroph is an organism that obtains energy by the oxidation of electron donors in their environments. These molecules can be organic ( chemoorganotrophs) or inorganic (chemolithotrophs). The chemotroph designation is in contrast to phototrophs, which use photons. Chemotrophs can be either autotrophic or heterotrophic. Chemotrophs can be found in areas where electron donors are present in high concentration, for instance around hydrothermal vents. Chemoautotroph Chemoautotrophs, in addition to deriving energy from chemical reactions, synthesize all necessary organic compounds from carbon dioxide. Chemoautotrophs can use inorganic energy sources such as hydrogen sulfide, elemental sulfur, ferrous iron, molecular hydrogen, and ammonia or organic sources to produce energy. Most chemoautotrophs are extremophiles, bacteria or archaea that live in hostile environments (such as deep sea vents) and are the primary producers in such ecosystems. Chemoautotrophs generally fall into s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Fixation
Biological carbon fixation or сarbon assimilation is the process by which inorganic carbon (particularly in the form of carbon dioxide) is converted to organic compounds by living organisms. The compounds are then used to store energy and as structure for other biomolecules. Carbon is primarily fixed through photosynthesis, but some organisms use a process called chemosynthesis in the absence of sunlight. Organisms that grow by fixing carbon are called autotrophs, which include photoautotrophs (which use sunlight), and lithoautotrophs (which use inorganic oxidation). Heterotrophs are not themselves capable of carbon fixation but are able to grow by consuming the carbon fixed by autotrophs or other heterotrophs. "Fixed carbon", "reduced carbon", and "organic carbon" may all be used interchangeably to refer to various organic compounds. Chemosynthesis is carbon fixation driven by chemical energy, rather than from sunlight. Sulfur- and hydrogen-oxidizing bacteria often use the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoautotrophism
Photoautotrophs are organisms that use light energy and inorganic carbon to produce organic materials. Eukaryotic photoautotrophs absorb energy through the chlorophyll molecules in their chloroplasts while prokaryotic photoautotrophs use chlorophylls and bacteriochlorophylls present in their cytoplasm. All known photoautotrophs perform photosynthesis. Examples include plants, algae, and cyanobacteria. Origin and the Great Oxidation Event Chemical and geological evidence indicate that photosynthetic cyanobacteria existed about 2.6 billion years ago and anoxygenic photosynthesis had been taking place since a billion years before that. Oxygenic photosynthesis was the primary source of oxygenation and led to the Great Oxidation Event (the Oxygen Catastrophe) roughly 2.4 to 2.1 billion years ago. Although the end of the Great Oxidation Event was marked by a significant decrease in gross primary productivity that eclipsed extinction events, the development of aerobic respiration enabled ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autotrophic
An autotroph or primary producer is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) using carbon from simple substances such as carbon dioxide,Morris, J. et al. (2019). "Biology: How Life Works", 3rd edition, W. H. Freeman. generally using energy from light (photosynthesis) or inorganic chemical reactions (chemosynthesis). They convert an abiotic source of energy (e.g. light) into energy stored in organic compounds, which can be used by other organisms (e.g. heterotrophs). Autotrophs do not need a living source of carbon or energy and are the producers in a food chain, such as plants on land or algae in water (in contrast to heterotrophs as consumers of autotrophs or other heterotrophs). Autotrophs can reduce carbon dioxide to make organic compounds for biosynthesis and as stored chemical fuel. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide. The primary produc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
André Lwoff
André — sometimes transliterated as Andre — is the French and Portuguese form of the name Andrew, and is now also used in the English-speaking world. It used in France, Quebec, Canada and other French-speaking countries. It is a variation of the Greek name ''Andreas'', a short form of any of various compound names derived from ''andr-'' 'man, warrior'. The name is popular in Norway and Sweden. Cognate names Cognate names are: * : Andrei, |
Chlorobium
''Chlorobium'' is a genus of green sulfur bacteria. They are photolithotrophic oxidizers of sulfur and most notably utilise a noncyclic electron transport chain to reduce NAD+. Photosynthesis is achieved using a Type 1 Reaction Centre using bacteriochlorophyll (BChl) ''a''. Two photosynthetic antenna complexes aid in light absorption: the Fenna-Matthews-Olson complex ("FMO", also containing BChl ''a''), and the chlorosomes which employ mostly BChl ''c'', ''d'', or ''e''. Hydrogen sulfide is used as an electron source and carbon dioxide its carbon source.Prescott, Harley, Klein. (2005). ''Microbiology'' pp. 195, 493, 597, 618-619, 339. ''Chlorobium'' species exhibit a dark green color; in a Winogradsky column, the green layer often observed is composed of ''Chlorobium''. This genus lives in strictly anaerobic conditions below the surface of a body of water, commonly the anaerobic zone of a eutrophic lake. '' Chlorobium aggregatum'' is a species which exists in a symbiotic rela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatium
''Chromatium'' is a genus of photoautotrophic Gram-negative bacteria which are found in water. The cells are straight rod-shaped or slightly curved. They belong to the purple sulfur bacteria and oxidize sulfide to produce sulfur which is deposited in intracellular granules of the cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ....George M. Garrity: '' Bergey's Manual of Systematic Bacteriology''. 2. Auflage. Springer, New York, 2005, Volume 2: ''The Proteobacteria, Part B: The Gammaproteobacteria'' References External links''Chromatium''J.P. Euzéby: List of Prokaryotic names with Standing in Nomenclature Chromatiales Phototrophic bacteria Bacteria genera {{Chromatiales-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhodobacter Capsulatus
''Rhodobacter capsulatus'' is a species of purple bacteria, a group of bacteria that can obtain energy through photosynthesis. Its name is derived from the Latin adjective "capsulatus" ("with a chest", "encapsulated"), itself derived Latin noun "capsula" (meaning "a small box or chest"), and the associated Latin suffix for masculine nouns, "-atus" (denoting that something is "provided with" something else). Its complete genome has been sequenced and is available to the public. Discovery The discovery of ''Rhodobacter capsulatus'' is attributed to Hans Molisch, a Czech-Austrian botanist. The microorganism, then named ''Rhodonostoc capsulatum'', was identified in 1907 in his book ''Die Purpurbakterien nach neuen Untersuchungen''. C. B. van Niel then characterized the species further in 1944 where it was renamed ''Rhodopseudomonas capsulata''. Van Niel initially described 16 strains of ''R. capsulata'' that he was able to culture from mud samples collected in California and Cuba. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
