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Archaella
The archaellum (; formerly archaeal flagellum) is a unique structure on the cell surface of many archaea, that allows for swimming motility. The archaellum consists of a rigid helical filament that is attached to the cell membrane by a molecular motor. This molecular motorcomposed of cytosolic, membrane, and pseudo-periplasmic proteinsis responsible for the assembly of the filament and, once assembled, for its rotation. The rotation of the filament propels archaeal cells in liquid medium, in a manner similar to the propeller of a boat. The bacterial analog of the archaellum is the flagellum, which is also responsible for their swimming motility and can also be compared to a rotating corkscrew. Although the movement of archaella and flagella is sometimes described as "whip-like", this is incorrect, as only cilia from Eukaryotes move in this manner. Indeed, even "flagellum" (word derived from Latin meaning "whip") is a misnomer, as bacterial flagella work are also propeller-like str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaea
Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria (in the Archaebacteria kingdom), but this term has fallen out of use. Archaeal cells have unique properties separating them from the other two domains, Bacteria and Eukaryota. Archaea are further divided into multiple recognized phyla. Classification is difficult because most have not been isolated in a laboratory and have been detected only by their gene sequences in environmental samples. Archaea and bacteria are generally similar in size and shape, although a few archaea have very different shapes, such as the flat, square cells of ''Haloquadratum walsbyi''. Despite this morphological similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes, notably for the enzymes involved ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methanocaldococcus Jannaschii
''Methanocaldococcus jannaschii'' (formerly ''Methanococcus jannaschii'') is a thermophilic methanogenic archaean in the class Methanococci. It was the first archaeon to have its complete genome sequenced. The sequencing identified many genes unique to the archaea. Many of the synthesis pathways for methanogenic cofactors were worked out biochemically in this organism, as were several other archaeal-specific metabolic pathways. History ''Methanocaldococcus jannaschii'' was isolated from a submarine hydrothermal vent at Woods Hole Oceanographic Institution. Sequencing ''Methanocaldococcus jannaschii'' was sequenced by a group at TIGR led by Craig Venter using whole-genome shotgun sequencing. ''Methanocaldococcus jannaschii'' represented the first member of the Archaea to have its genome sequenced. According to Venter, the unique features of the genome provided strong evidence that there are three domains of life. Taxonomy ''Methanocaldoccus jannaschii'' is a member o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RecA
RecA is a 38 kilodalton protein essential for the repair and maintenance of DNA. A RecA structural and functional homolog has been found in every species in which one has been seriously sought and serves as an archetype for this class of homologous DNA repair proteins. The homologous protein is called RAD51 in eukaryotes and RadA in archaea. RecA has multiple activities, all related to DNA repair. In the bacterial SOS response, it has a co-protease function in the autocatalytic cleavage of the LexA repressor and the λ repressor. RecA's association with DNA repair is based on its central role in homologous recombination. The RecA protein binds strongly and in long clusters to ssDNA to form a nucleoprotein filament. The protein has more than one DNA binding site, and thus can hold a single strand and double strand together. This feature makes it possible to catalyze a DNA synapsis reaction between a DNA double helix and a complementary region of single-stranded DNA. The RecA-s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenosine Triphosphate
Adenosine triphosphate (ATP) is an organic compound that provides energy to drive many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis. Found in all known forms of life, ATP is often referred to as the "molecular unit of currency" of intracellular energy transfer. When consumed in metabolic processes, it converts either to adenosine diphosphate (ADP) or to adenosine monophosphate (AMP). Other processes regenerate ATP. The human body recycles its own body weight equivalent in ATP each day. It is also a precursor to DNA and RNA, and is used as a coenzyme. From the perspective of biochemistry, ATP is classified as a nucleoside triphosphate, which indicates that it consists of three components: a nitrogenous base (adenine), the sugar ribose, and the Polyphosphate, triphosphate. Structure ATP consists of an adenine attached by the 9-nitrogen atom to the 1′ carbon atom of a sugar (ribose), which i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prepilin Peptidase
Prepilin peptidase () is an enzyme found in Type IV filament systems responsible for the maturation of the pilin. This enzyme catalyses the following chemical reaction : Typically cleaves a -Gly-Phe- bond to release an N-terminal, basic peptide of 5-8 residues from type IV prepilin, and then N-methylates the new N-terminal amino group, the methyl donor being ''S''-adenosyl-L-methionine. This enzyme is present on the surface of many species of bacteria. All known enzymes with this activity are of the MEROPS MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibitor ... family A24. References External links * MEROPS A24 {{Portal bar, Biology, border=no EC 3.4.23 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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MW or mW may refer to: Science and technology *MediaWiki, (MW) the software that runs MediaWiki-powered websites *Megawatt, (MW) a unit of power *Milliwatt, (mW) one thousandth of a watt *.mw, the country code top level domain (ccTLD) for Malawi *Medium wave, (MW) frequency range of 530 to 1700 kHz (commonly called the AM band) *Molecular weight, a former term for molecular mass *Microwave, a type of electromagnetic wave *Moment magnitude scale (), a measure of earthquake size *Weight average molecular weight Arts and entertainment Games *'' Call of Duty 4: Modern Warfare'', a 2007 first person shooter *'' Call of Duty: Modern Warfare'', a 2019 first person shooter *'' MechWarrior'', a video game series first released in 1989 * Need for Speed: Most Wanted (other), two racing video games released in 2005 and 2012 Other media * ''MW'' (manga), a manga series by Osamu Tezuka *Miss World, an international beauty pageant *Museums and the Web, an international conference ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halobacterium Salinarum
''Halobacterium salinarum'', formerly known as ''Halobacterium cutirubrum'' or ''Halobacterium halobium'', is an extremely halophilic marine obligate aerobic archaeon. Despite its name, this is not a bacterium, but a member of the domain Archaea. It is found in salted fish, hides, hypersaline lakes, and salterns. As these salterns reach the minimum salinity limits for extreme halophiles, their waters become purple or reddish color due to the high densities of halophilic Archaea. ''H. salinarum'' has also been found in high-salt food such as salt pork, marine fish, and sausages. The ability of ''H. salinarum'' to survive at such high salt concentrations has led to its classification as an extremophile. Cell morphology and metabolism Halobacteria are single-celled, rod-shaped microorganisms that are among the most ancient forms of life and appeared on Earth billions of years ago. The membrane consists of a single lipid bilayer surrounded by an S-layer. The S-layer is made of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euryarchaeota
Euryarchaeota (from Ancient Greek ''εὐρύς'' eurús, "broad, wide") is a phylum of archaea. Euryarchaeota are highly diverse and include methanogens, which produce methane and are often found in intestines, halobacteria, which survive extreme concentrations of salt, and some extremely thermophilic aerobes and anaerobes, which generally live at temperatures between 41 and 122 °C. They are separated from the other archaeans based mainly on rRNA sequences and their unique DNA polymerase. Description The ''Euryarchaeota'' are diverse in appearance and metabolic properties. The phylum contains organisms of a variety of shapes, including both rods and cocci. ''Euryarchaeota'' may appear either gram-positive or gram-negative depending on whether pseudomurein is present in the cell wall. ''Euryarchaeota'' also demonstrate diverse lifestyles, including methanogens, halophiles, sulfate-reducers, and extreme thermophiles in each. Others live in the ocean, suspended with plankton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type IV Pili
A pilus (Latin for 'hair'; plural: ''pili'') is a hair-like appendage found on the surface of many bacteria and archaea. The terms ''pilus'' and '' fimbria'' (Latin for 'fringe'; plural: ''fimbriae'') can be used interchangeably, although some researchers reserve the term ''pilus'' for the appendage required for bacterial conjugation. All conjugative pili are primarily composed of pilin – fibrous proteins, which are oligomeric. Dozens of these structures can exist on the bacterial and archaeal surface. Some bacteria, viruses or bacteriophages attach to receptors on pili at the start of their reproductive cycle. Pili are antigenic. They are also fragile and constantly replaced, sometimes with pili of different composition, resulting in altered antigenicity. Specific host responses to old pili structures are not effective on the new structure. Recombination genes of pili code for variable (V) and constant (C) regions of the pili (similar to immunoglobulin diversity). As the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrococcus Horikoshii
''Pyrococcus horikoshii'' is a hyperthermophilic, anaerobic archaeon, first isolated from hydrothermal fluid samples obtained at the Okinawa Trough vents at a depth of . It is obligately heterotrophic, cells are irregular cocci with a tuft of flagella, growing optimally at 98 °C, sulphur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ... greatly enhancing its growth. References Further reading * * * * * External links *WORMS entry [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeoglobus Fulgidus
''Archaeoglobus'' is a genus of the phylum Euryarchaeota. ''Archaeoglobus'' can be found in high-temperature oil fields where they may contribute to oil field souring. Metabolism ''Archaeoglobus'' grow anaerobically at extremely high temperatures between 60 and 95 °C, with optimal growth at 83 °C (ssp. ''A. fulgidus'' VC-16). They are sulfate-reducing archaea, coupling the reduction of sulfate to sulfide with the oxidation of many different organic carbon sources, including complex polymers. ''A. lithotrophicus'' live chemolitho-autotrophically from hydrogen, sulfate and carbon dioxide. Also ''A. profundus'' grow lithotrophically, but while this species needs acetate and CO2 for biosynthesis they are heterotroph. The complete ''A. fulgidus'' genome sequence revealed the presence of a nearly complete set of genes for methanogenesis. The function of these genes in ''A. fulgidus'' remains unknown, while the lack of the enzyme methyl-CoM reductase does not allow for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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