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Mitochondria
A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. They were discovered by Albert von Kölliker in 1857 in the voluntary muscles of insects. The term ''mitochondrion'' was coined by Carl Benda in 1898. The mitochondrion is popularly nicknamed the "powerhouse of the cell", a phrase coined by Philip Siekevitz in a 1957 article of the same name. Some cells in some multicellular organisms lack mitochondria (for example, mature mammalian red blood cells). A large number of unicellular organisms, such as microsporidia, parabasalids and diplomonads, have reduced or transformed their mitochondria into other structures. One eukaryote, ''Monocercomonoides'', is known to have completely lost its mitochondria, and one multicellular organism, ' ... [...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] |
Monocercomonoides
''Monocercomonoides'' is a genus of flagellate Excavata belonging to the order Oxymonadida. It was established by Bernard V. Travis and was first described as those with "polymastiginid flagellates having three anterior flagella and a trailing one originating at a single basal granule located in front of the anteriorly positioned nucleus, and a more or less well-defined axostyle". It is the first eukaryotic genus to be found to completely lack mitochondria, and all hallmark proteins responsible for mitochondrial function. The genus also lacks any other mitochondria related organelles (MROs) such as hydrogenosomes or mitosomes. Data suggests that the absence of mitochondria is not an ancestral feature, but rather due to secondary loss. ''Monocercomonoides ''sp. was found to obtain energy through an enzymatic action of nutrients absorbed from the environment. The genus has replaced the iron-sulfur cluster assembly pathway with a cytosolic sulfur mobilization system, likely ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerobic Respiration
Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor such as oxygen to produce large amounts of energy, to drive the bulk production of ATP. Cellular respiration may be described as a set of metabolic reactions and processes that take place in the cells of organisms to convert chemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, releasing energy. Respiration is one of the key ways a cell releases chemical energy to fuel cellular activity. The overall reaction occurs in a series of biochemical steps, some of which are redox reactions. Although cellular respiration is technically a combustion reaction, it is an unusual one because of the slow, controlled release of energy from the series of reactions. Nutrients that are commonly used by animal and pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitosome
A mitosome is an organelle found in some unicellular eukaryotic organisms, like in members of the supergroup Excavata. The mitosome was found and named in 1999, and its function has not yet been well characterized. It was termed a ''crypton'' by one group, but that name is no longer in use. The mitosome has been detected only in anaerobic or microaerophilic organisms that do not have mitochondria. These organisms do not have the capability of gaining energy from oxidative phosphorylation, which is normally performed by mitochondria. The mitosome was first described in ''Entamoeba histolytica,'' an intestinal parasite of humans. Mitosomes have also been identified in several species of Microsporidia and in '' Giardia intestinalis''. Origin and function Mitosomes are almost certainly derived from mitochondria. Like mitochondria, they have a double membrane and most proteins are delivered to them by a targeting sequence of amino acids. The targeting sequence is similar to that u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henneguya Zschokkei
''Henneguya zschokkei'' or ''Henneguya salminicola'' is a species of a myxosporean endoparasite. It afflicts several salmon in the genus ''Oncorhynchus''. It causes milky flesh or tapioca disease. ''H. zschokkei'' is notable for its absence of mitochondria, mitochondrial DNA, aerobic respiration and its reliance on an as yet undiscovered energy metabolism. Description ''Henneguya salminicola'' is found in fish as an ovoid spore with two anterior polar capsules and two long caudal appendages. Individuals are very small (about 10 micrometers in diameter), but are found aggregated into cysts 3–6 mm in diameter at any place in the muscle mass. Unknown metabolism ''Henneguya salminicola'' is the only known multicellular animal that does not rely on the aerobic respiration of oxygen. It lacks a mitochondrial genome and therefore mitochondria, making it one of the only members of the eukaryotic animal kingdom to shun oxygen as the foundation of its metabolism. The means by ... [...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 triphosphate. Structure ATP consists of an adenine attached by the 9-nitrogen atom to the 1′ carbon atom of a sugar ( ribose), which in tu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell (biology)
The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites.Cell Movements and the Shaping of the Vertebrate Body in Chapter 21 of Molecular Biology of the Cell '' fourth edition, edited by Bruce Alberts (2002) published by Garland Science. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos. It is also common to describe small molecules such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unicellular Organism
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms. All prokaryotes are unicellular and are classified into bacteria and archaea. Many eukaryotes are multicellular, but some are unicellular such as protozoa, unicellular algae, and unicellular fungi. Unicellular organisms are thought to be the oldest form of life, with early protocells possibly emerging 3.8–4.0 billion years ago. Although some prokaryotes live in colonies, they are not specialised cells with differing functions. These organisms live together, and each cell must carry out all life processes to survive. In contrast, even the simplest multicellular organisms have cells that depend on each other to survive. Most multicellular organisms have a unicellular life-cycle stage. Gametes, for example, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organelle
In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' the suffix ''-elle'' being a diminutive. Organelles are either separately enclosed within their own lipid bilayers (also called membrane-bound organelles) or are spatially distinct functional units without a surrounding lipid bilayer (non-membrane bound organelles). Although most organelles are functional units within cells, some function units that extend outside of cells are often termed organelles, such as cilia, the flagellum and archaellum, and the trichocyst. Organelles are identified by microscopy, and can also be purified by cell fractionation. There are many types of organelles, particularly in eukaryotic cells. They include structures that make up the endomembrane system (such as the nuclear envelope, endoplasmic reticulum, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parabasalid
The parabasalids are a group of flagellated protists within the supergroup Excavata. Most of these eukaryotic organisms form a symbiotic relationship in animals. These include a variety of forms found in the intestines of termites and cockroaches, many of which have symbiotic bacteria that help them digest cellulose in woody plants. Other species within this supergroup are known parasites, and include human pathogens. Characteristics The flagella are arranged in one or more clusters near the anterior of the cell. Their basal bodies are linked to parabasal fibers that attach to prominent Golgi complexes, distinctive to the group. Usually they also give rise to a sheet of cross-like microtubules that runs down the center of the cell and in some cases projects past the end. This is called the axostyle, but is different in structure from the axostyles of oxymonads. Parabasalids are anaerobic, and lack mitochondria, but this is now known to be a result of secondary loss, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diplomonad
The diplomonads (Greek for "two units") are a group of flagellates, most of which are parasitic. They include ''Giardia duodenalis'', which causes giardiasis in humans. They are placed among the metamonads, and appear to be particularly close relatives of the retortamonads. Most diplomonads are double cells: they have two nuclei, each with four associated flagella, arranged symmetrically about the body's main axis. Like the retortamonads, they lack both mitochondria and Golgi apparatuses. However, they are now known to possess modified mitochondria, in the case of ''G. duodenalis'', called mitosomes. These are not used in ATP synthesis the way mitochondria are, but are involved in the maturation of iron-sulfur proteins. Possible sexual reproduction in ''Giardia'' The common intestinal parasite ''Giardia duodenalis'' (synonyms ''Giardia lamblia'', ''G. intestinalis'') was once considered to be a descendant of a protist lineage that predated the emergence of meiosis and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
