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Microneme
Micronemes are secretory organelles, possessed by parasitic apicomplexans. Micronemes are located on the apical third of the protozoan body. They are surrounded by a typical unit membrane. On electron microscopy they have an electron-dense matrix due to the high protein content. They are specialized secretory organelles important for host-cell invasion and gliding motility. These organelles secrete several proteins such as the ''Plasmodium falciparum ''Plasmodium falciparum'' is a Unicellular organism, unicellular protozoan parasite of humans and is the deadliest species of ''Plasmodium'' that causes malaria in humans. The parasite is transmitted through the bite of a female ''Anopheles'' mos ...'' apical membrane antigen-1, or PfAMA1, and Erythrocyte family antigen, or EBA, family proteins. These proteins specialize in binding to erythrocyte surface receptors and facilitating erythrocyte entry. Only by this initial chemical exchange can the parasite enter into the er ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhoptry
A rhoptry is a specialized secretory organelle. They are club-shaped organelles connected by thin necks to the extreme apical pole of the parasite. These organelles, like micronemes, are characteristic of the motile stages of Apicomplexa protozoans. They can vary in number and shape and contain numerous enzymes that are released during the process of host penetration. The proteins they contain are important in the interaction between the host and the parasite, including the formation of the parasitophorous vacuole (PV). Characteristics Rhoptries are one of the three characteristic secretory organelles present in all Apicomplexa along with micronemes and dense granules. Rhoptries and micronemes are localized at the apical complex of the Apicomplexan organism, which suggests common ancestry of the members of the phylum and the evolution process they have experienced. The name rhoptry indicates its shape as it comes from the Greek word for “club-shaped.” These large membrane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasitophorous Vacuole
The parasitophorous vacuole (PV) is a structure produced by apicomplexan parasites in the cells of its host. The PV allows the parasite to develop while protected from the phagolysosomes of the host cell. The PV is a bubble-like compartment made of plasma membrane; the compartment contains cytoplasm and the parasite. The PV allows the parasite to exist and grow within the cell while protecting the parasite from the host cell defense mechanisms. The PV prevents the acidification of the compartment, the mechanism by which the lysosomes of the host cell would normally destroy an invading parasite. Parasites that form a parasitophorous vacuole as part of their infection process include ''Plasmodium falciparum'', which causes malaria and ''Toxoplasma gondii'', which causes toxoplasmosis. The parasitophorous vacuole is formed during cell invasion, when the parasite uses part of the membrane of the host cell to form a parasitophorous vacuolar membrane (PVM). The PVM surrounds the intrac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasmodium Falciparum
''Plasmodium falciparum'' is a Unicellular organism, unicellular protozoan parasite of humans and is the deadliest species of ''Plasmodium'' that causes malaria in humans. The parasite is transmitted through the bite of a female ''Anopheles'' mosquito and causes the disease's most dangerous form, falciparum malaria. ''P. falciparum'' is therefore regarded as the deadliest parasite in humans. It is also associated with the development of blood cancer (Burkitt's lymphoma) and is classified as a List of IARC Group 2A carcinogens, Group 2A (probable) carcinogen. The species originated from the malarial parasite ''Laverania'' found in gorillas, around 10,000 years ago. Alphonse Laveran was the first to identify the parasite in 1880, and named it ''Oscillaria malariae''. Ronald Ross discovered its transmission by mosquito in 1897. Giovanni Battista Grassi elucidated the complete transmission from a female Anopheles, anopheline mosquito to humans in 1898. In 1897, William H. Welch create ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apicomplexa
The Apicomplexa (also called Apicomplexia; single: apicomplexan) are organisms of a large phylum of mainly parasitic alveolates. Most possess a unique form of organelle structure that comprises a type of non-photosynthetic plastid called an apicoplastwith an apical complex membrane. The organelle's apical shape is an adaptation that the apicomplexan applies in penetrating a host cell. The Apicomplexa are unicellular and spore-forming. Most are obligate endoparasites of animals, except '' Nephromyces'', a symbiont in marine animals, originally classified as a chytrid fungus, and the Chromerida, some of which are photosynthetic partners of corals. Motile structures such as flagella or pseudopods are present only in certain gamete stages. The Apicomplexa are a diverse group that includes organisms such as the coccidia, gregarines, piroplasms, haemogregarines, and plasmodia. Diseases caused by Apicomplexa include: * Babesiosis ('' Babesia'') * Malaria (''Plasmodium'') * Cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duffy Binding Proteins
In molecular biology, Duffy binding proteins are found in Plasmodium. ''Plasmodium vivax'' and ''Plasmodium knowlesi'' merozoites invade ''Homo sapiens'' erythrocytes that express Duffy blood group surface determinants. The Duffy receptor family is localised in micronemes, an organelle found in all organisms of the phylum Apicomplexa. The presence of duffy-binding-like domains defines the family of erythrocyte binding-like proteins (EBL), a family of cell invasion proteins universal among ''Plasmodium''. These other members may use some other receptor, for example Glycophorin A. The other universal invasion protein is reticulocyte binding protein homologs. Both families are essential for cell invasion, as they function cooperatively. A duffy-binding-like domain is also found in proteins of the family ''Plasmodium falciparum'' erythrocyte membrane protein 1. See also *Genetic resistance to malaria Human genetic resistance to malaria refers to inherited changes in the DNA of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dense Granule
Dense granules (also known as dense bodies or delta granules) are specialized secretory organelles. Dense granules are found only in platelets and are smaller than alpha granules.Michelson, A. D. (2013). ''Platelets'' (Vol. 3rd ed). Amsterdam: Academic Press. The origin of these dense granules is still unknown, however, it is thought that may come from the mechanism involving the endocytotic pathway.Ambrosio, A. L., Boyle, J. A., & Di Pietro, S. M. (2012). Mechanism of platelet dense granule biogenesis: study of cargo transport and function of Rab32 and Rab38 in a model system. ''Blood'', ''120''(19), 4072–4081. Dense granules are a sub group of lysosome-related organelles (LRO). There are about three to eight of these in a normal human platelet.McNicol, A., & Israels, S. J. (1999). ''Platelet dense granules: Structure, function and implications for haemostasis'' In unicellular organisms They are found in animals and in unicellular organisms including Apicomplexa protozoans. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protozoa
Protozoa (: protozoan or protozoon; alternative plural: protozoans) are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris. Historically, protozoans were regarded as "one-celled animals". When first introduced by Georg Goldfuss, in 1818, the taxon Protozoa was erected as a class within the Animalia, with the word 'protozoa' meaning "first animals", because they often possess animal-like behaviours, such as motility and predation, and lack a cell wall, as found in plants and many algae. This classification remained widespread in the 19th and early 20th century, and even became elevated to a variety of higher ranks, including phylum, subkingdom, kingdom, and then sometimes included within the paraphyletic Protoctista or Protista. By the 1970s, it became usual to require that all taxa be monophyletic (derived from a common ancestor that would also be regarded as protozo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Membrane
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of a cell, being selectively permeable to ions and organic mole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metabolic reactions, DNA replication, Cell signaling, responding to stimuli, providing Cytoskeleton, structure to cells and Fibrous protein, organisms, and Intracellular transport, transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the Nucleic acid sequence, nucleotide sequence of their genes, and which usually results in protein folding into a specific Protein structure, 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called pep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliding Motility
Gliding motility is a type of translocation used by microorganisms that is independent of propulsive structures such as flagella, pili, and fimbriae. Gliding allows microorganisms to travel along the surface of low aqueous films. The mechanisms of this motility are only partially known. Twitching motility also allows microorganisms to travel along a surface, but this type of movement is jerky and uses pili as its means of transport. Bacterial gliding is a type of gliding motility that can also use pili for propulsion. The speed of gliding varies between organisms, and the reversal of direction is seemingly regulated by some sort of internal clock. For example the apicomplexans are able to travel at fast rates between 1–10 μm/s. In contrast '' Myxococcus xanthus'' bacteria glide at a rate of 0.08 μm/s. Types of motility Bacterial gliding is a process of motility whereby a bacterium can move under its own power. Generally, the process occurs whereby the bacteriu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organelles
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-bounded organelles) or are spatially distinct functional units without a surrounding lipid bilayer (non-membrane bounded organelles). Although most organelles are functional units within cells, some functional units that extend outside of cells are often termed organelles, such as cilia, the flagellum and archaellum, and the trichocyst (these could be referred to as membrane bound in the sense that they are attached to (or bound to) the membrane). Organelles are identified by microscopy, and can also be purified by cell fractionation. There are many types of organelles, particularly in eukaryotic cells. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
