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Diphoda
A bikont ("two flagella") is any of the eukaryotic organisms classified in the group Bikonta. Many single-celled members of the group, and the presumed ancestor, have two flagella. Enzymes Another shared trait of bikonts is the fusion of two genes into a single unit: the genes for thymidylate synthase (TS) and dihydrofolate reductase (DHFR) encode a single protein with two functions. The genes are separately translated in unikonts. Relationships Some research suggests that a unikont (a eukaryotic cell with a single flagellum) was the ancestor of opisthokonts (Animals, Fungi, and related forms) and Amoebozoa, and a bikont was the ancestor of Archaeplastida (Plants and relatives), Excavata, Rhizaria, and Chromalveolata. Cavalier-Smith has suggested that Apusozoa, which are typically considered ''incertae sedis'', are in fact bikonts. Relationships within the bikonts are not yet clear. Cavalier-Smith has grouped the Excavata and Rhizaria into the Cabozoa and the Archaepl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryote
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard archaea. This implies that there are only two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as flagellated phagotrophs. Their name comes from the Greek εὖ (''eu'', "well" or "good") and κάρυον (''karyon'', "nut" or "kernel"). E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryote
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard archaea. This implies that there are only two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as flagellated phagotrophs. Their name comes from the Greek εὖ (''eu'', "well" or "good") and κάρυον (''karyon'', "nut" or "kernel"). E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scotokaryotes
The Scotokaryotes (Cavalier-Smith) is a proposed basal Neokaryote clade as sister of the Diaphoretickes. Basal Scotokaryote groupings are the Metamonads, the Malawimonas and the Podiata. In this phylogeny the Discoba are sometimes seen as paraphyletic and basal Eukaryotes. An alternative to the Unikont– Bikont division was suggested by Derelle ''et al.'' in 2015, where they proposed the acronyms Opimoda–Diphoda respectively, as substitutes to the older terms. The name Opimoda is formed from the letters (shown in capitals) of OPIsthokonta and aMOebozoa. In this phylogeny Discoba belongs to the Diphoda clade. Taxonomy A proposed cladogram is See also *Diphoda A bikont ("two flagella") is any of the eukaryotic organisms classified in the group Bikonta. Many single-celled members of the group, and the presumed ancestor, have two flagella. Enzymes Another shared trait of bikonts is the fusion of two ... References {{Taxonbar, from=Q21399998 Eukaryote unran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excavata
Excavata is a major supergroup of unicellular organisms belonging to the domain Eukaryota. It was first suggested by Simpson and Patterson in 1999 and introduced by Thomas Cavalier-Smith in 2002 as a formal taxon. It contains a variety of free-living and symbiotic forms, and also includes some important parasites of humans, including ''Giardia'' and ''Trichomonas''. Excavates were formerly considered to be included in the now obsolete Protista kingdom. They are classified based on their flagellar structures, and they are considered to be the most basal flagellate lineage. Phylogenomic analyses split the members of Excavata into three different and not all closely related groups: Discobids, Metamonads and Malawimonads. Except for Euglenozoa, they are all non-photosynthetic. Characteristics Most excavates are unicellular, heterotrophic flagellates. Only the Euglenozoa are photosynthetic. In some (particularly anaerobic intestinal parasites), the mitochondria have been greatly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discoba
Excavata is a major supergroup of unicellular organisms belonging to the domain Eukaryota. It was first suggested by Simpson and Patterson in 1999 and introduced by Thomas Cavalier-Smith in 2002 as a formal taxon. It contains a variety of free-living and symbiotic forms, and also includes some important parasites of humans, including '' Giardia'' and '' Trichomonas''. Excavates were formerly considered to be included in the now obsolete Protista kingdom. They are classified based on their flagellar structures, and they are considered to be the most basal flagellate lineage. Phylogenomic analyses split the members of Excavata into three different and not all closely related groups: Discobids, Metamonads and Malawimonads. Except for Euglenozoa, they are all non-photosynthetic. Characteristics Most excavates are unicellular, heterotrophic flagellates. Only the Euglenozoa are photosynthetic. In some (particularly anaerobic intestinal parasites), the mitochondria have been grea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amoebozoa
Amoebozoa is a major taxonomic group containing about 2,400 described species of amoeboid protists, often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae. In traditional and currently no longer supported classification schemes, Amoebozoa is ranked as a phylum within either the kingdom Protista or the kingdom Protozoa. In the classification favored by the International Society of Protistologists, it is retained as an unranked " supergroup" within Eukaryota. Molecular genetic analysis supports Amoebozoa as a monophyletic clade. Modern studies of eukaryotic phylogenetic trees identify it as the sister group to Opisthokonta, another major clade which contains both fungi and animals as well as several other clades comprising some 300 species of unicellular eukaryotes. Amoebozoa and Opisthokonta are sometimes grouped together in a high-level taxon, variously named Unikonta, Amorphea or Opimoda. Amoebozoa includes many of the best-known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesoproterozoic
The Mesoproterozoic Era is a geologic era that occurred from . The Mesoproterozoic was the first era of Earth's history for which a fairly definitive geological record survives. Continents existed during the preceding era (the Paleoproterozoic), but little is known about them. The continental masses of the Mesoproterozoic were more or less the same ones that exist today, although their arrangement on the Earth's surface was different. Major events and characteristics The major events of this era are the breakup of the Columbia supercontinent, the formation of the Rodinia supercontinent, and the evolution of sexual reproduction. This era is marked by the further development of continental plates and plate tectonics. The supercontinent of Columbia broke up between 1500 and 1350 million years ago, and the fragments reassembled into the supercontinent of Rodinia around 1100 to 900 million years ago, on the time boundary between the Mesoproterozoic and the subsequent Neoproterozoi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromalveolata
Chromalveolata was a eukaryote supergroup present in a major classification of 2005, then regarded as one of the six major groups within the eukaryotes. It was a refinement of the kingdom Chromista, first proposed by Thomas Cavalier-Smith in 1981. Chromalveolata was proposed to represent the organisms descended from a single secondary endosymbiosis involving a red alga and a bikont. The plastids in these organisms are those that contain chlorophyll c. However, the monophyly of the Chromalveolata has been rejected. Thus, two papers published in 2008 have phylogenetic trees in which the chromalveolates are split up, and recent studies continue to support this view. Groups and classification Historically, many chromalveolates were considered plants, because of their cell walls, photosynthetic ability, and in some cases their morphological resemblance to the land plants (Embryophyta). However, when the five-kingdom system (proposed in 1969) took prevalence over the animal� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incertae Sedis
' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty at specific taxonomic levels is indicated by ' (of uncertain family), ' (of uncertain suborder), ' (of uncertain order) and similar terms. Examples *The fossil plant '' Paradinandra suecica'' could not be assigned to any family, but was placed ''incertae sedis'' within the order Ericales when described in 2001. * The fossil '' Gluteus minimus'', described in 1975, could not be assigned to any known animal phylum. The genus is therefore ''incertae sedis'' within the kingdom Animalia. * While it was unclear to which order the New World vultures (family Cathartidae) should be assigned, they were placed in Aves ''incertae sedis''. It was later agreed to place them in a separate order, Cathartiformes. * Bocage's longbill, ''Motacilla boca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cabozoa
In the classification of eukaryotes (living organisms with a cell nucleus), Cabozoa was a taxon proposed by Cavalier-Smith. It was a putative clade comprising the Rhizaria and Excavata. More recent research tends to place the Rhizaria with the Alveolata and heterokonts instead of the Excavata, however. See also *Corticata Corticata ("one with a cortex"), in the classification of eukaryotes (living organisms with a cell nucleus), is a clade suggested by Thomas Cavalier-Smith to encompass the eukaryote supergroups of the following two groups: * Plantae, or Archaepl ... References Obsolete eukaryote taxa Bikont unranked clades {{Bikont-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acronym
An acronym is a word or name formed from the initial components of a longer name or phrase. Acronyms are usually formed from the initial letters of words, as in ''NATO'' (''North Atlantic Treaty Organization''), but sometimes use syllables, as in ''Benelux'' (short for ''Belgium, the Netherlands, and Luxembourg''). They can also be a mixture, as in ''radar'' (''Radio Detection And Ranging''). Acronyms can be pronounced as words, like ''NASA'' and ''UNESCO''; as individual letters, like ''FBI'', '' TNT'', and ''ATM''; or as both letters and words, like '' JPEG'' (pronounced ') and ''IUPAC''. Some are not universally pronounced one way or the other and it depends on the speaker's preference or the context in which it is being used, such as '' SQL'' (either "sequel" or "ess-cue-el"). The broader sense of ''acronym''—the meaning of which includes terms pronounced as letters—is sometimes criticized, but it is the term's original meaning and is in common use. Dictionary and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corticata
Corticata ("one with a cortex"), in the classification of eukaryotes (living organisms with a cell nucleus), is a clade suggested by Thomas Cavalier-Smith to encompass the eukaryote supergroups of the following two groups: * Plantae, or Archaeplastida (plants, red algae, green algae, and glaucophytes) * Chromalveolata (a group including kelp, water moulds, ciliates, dinoflagellates, and other organisms) Cavalier-Smith currently includes Rhizaria as well, resulting in an equivalency to Diaphoretickes. See also * Bikont *Cabozoa In the classification of eukaryotes (living organisms with a cell nucleus), Cabozoa was a taxon proposed by Cavalier-Smith. It was a putative clade comprising the Rhizaria and Excavata. More recent research tends to place the Rhizaria with th ... References Bikont unranked clades Diaphoretickes {{Bikont-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
