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Pelomyxina
The Archamoebae are a group of protists originally thought to have evolved before the acquisition of mitochondria by eukaryotes. They include genera that are internal parasites or commensals of animals (''Entamoeba'' and '' Endolimax''). A few species are human pathogens, causing diseases such as amoebic dysentery. The other genera of archamoebae live in freshwater habitats and are unusual among amoebae in possessing flagella. Most have a single nucleus and flagellum, but the giant amoeba ''Pelomyxa'' has many of each. Description Archamoebae are a diverse group of amoebae. Many have flagella for motility, while others do not. They grow in the absence of oxygen, though some can tolerate small amounts. Most described species of Archamoebae either lack mitochondria or are described to have reduced mitosomes. Habitat They thrive and live in soil, freshwater, and marine habitats. History The group Archamoebae was proposed by Thomas Cavalier-Smith in 1998 as part of the Archezoa, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RRNA
Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal DNA (rDNA) and then bound to ribosomal proteins to form SSU rRNA, small and LSU rRNA, large ribosome subunits. rRNA is the physical and mechanical factor of the ribosome that forces transfer RNA (tRNA) and messenger RNA (mRNA) to process and Translation (biology), translate the latter into proteins. Ribosomal RNA is the predominant form of RNA found in most cells; it makes up about 80% of cellular RNA despite never being translated into proteins itself. Ribosomes are composed of approximately 60% rRNA and 40% ribosomal proteins, though this ratio differs between Prokaryote, prokaryotes and Eukaryote, eukaryotes. Structure Although the primary structure of rRNA sequences can vary across organisms, Base pair, base-pairing within these sequ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitosomes
A mitosome (also called a ''crypton'' in early literature) is a mitochondrion-related organelle (MRO) found in a variety of parasitic unicellular eukaryotes, such as members of the supergroup Excavata. The mitosome was first discovered in 1999 in ''Entamoeba histolytica,'' an intestinal parasite of humans, and mitosomes have also been identified in several species of Microsporidia and in '' Giardia intestinalis''. The mitosome has been detected only in anaerobic or microaerophilic eukaryotes which do not have fully developed mitochondria, and hence do not have the capability of gaining energy from mitochondrial oxidative phosphorylation. The functions of mitosomes, while varied, have not yet been well characterized, but they may be associated with sulfate metabolism and biosynthesis of phospholipids and Fe–S clusters. Mitosomes, like other MROs, likely evolved from mitochondria, based on similarities in structure, function, and biochemical signaling pathways, and may have converge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Cavalier-Smith
Thomas (Tom) Cavalier-Smith, FRS, FRSC, NERC Professorial Fellow (21 October 1942 – 19 March 2021), was a professor of evolutionary biology in the Department of Zoology, at the University of Oxford. His research has led to discovery of a number of unicellular organisms (protists) and advocated for a variety of major taxonomic groups, such as the Chromista, Chromalveolata, Opisthokonta, Rhizaria, and Excavata. He was known for his systems of classification of all organisms. Life and career Cavalier-Smith was born on 21 October 1942 in London. His parents were Mary Maude (née Bratt) and Alan Hailes Spencer Cavalier Smith. He was educated at Norwich School, Gonville and Caius College, Cambridge (MA) in Biology and King's College London (PhD) in Zoology. He was under the supervision of Sir John Randall for his PhD thesis between 1964 and 1967; his thesis was entitled "''Organelle Development in'' Chlamydomonas reinhardii". From 1967 to 1969, Cavalier-S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archezoa
In biology, Archezoa is a term that has been introduced by several authors to refer to a group of organisms (a taxon). Authors include Josef Anton Maximilian Perty, Ernst Haeckel and in the 20th century by Thomas Cavalier-Smith in his classification system. Each author used the name to refer to different arrays of organisms. This reuse by later authors of the same taxon name for different groups of organisms is widely criticized in taxonomy because the inclusion of the name in a sentence (e.g. "Archezoa have no olfactory organs") does not make sense unless the particular usage is specified (e.g. "Archezoa ''sensu'' Cavalier-Smith (1987) have no olfactory organs"). Nonetheless, all uses of 'Archezoa' are now obsolete. Archezoa ''sensu'' Cavalier-Smith (1987) Cavalier-Smith proposed the term 'Archezoa' for a paraphyletic (see Paraphyly) territory of eukaryotes that primitively lacked mitochondria. Like Margulis and others before (see Pelomyxa), Cavalier-Smith argued that the i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entamoeba Histolytica
''Entamoeba histolytica'' is an anaerobic organism, anaerobic parasitic amoebozoan, part of the genus ''Entamoeba''. Predominantly infecting humans and other primates causing amoebiasis, ''E. histolytica'' is estimated to infect about 35-50 million people worldwide. ''E. histolytica'' infection is estimated to kill more than 55,000 people each year. Previously, it was thought that 10% of the world population was infected, but these figures predate the recognition that at least 90% of these infections were due to a second species, ''E. dispar''. Mammals such as dogs and cats can become infected transiently, but are not thought to contribute significantly to transmission. The word ''histolysis'' literally means disintegration and dissolution of organic tissues. Transmission The active (trophozoite) stage exists only in the host and in fresh loose feces; Microbial cyst, cysts survive outside the host in water, in soils, and on foods, especially under moist conditions on the lat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
