Endoplasm generally refers to the inner (often granulated), dense part of a cell's cytoplasm . This is opposed to the ectoplasm which is the outer (non-granulated) layer of the cytoplasm , which is typically watery and immediately adjacent to the plasma membrane. The nucleus is separated from the endoplasm by the nuclear envelope. The different makeups/viscosities of the endoplasm and ectoplasm contribute to the amoeba's locomotion through the formation of a pseudopod. However, other types of cells have cytoplasm divided into endo- and ectoplasm. The endoplasm, along with its granules, contains water, nucleic acids, amino acids, carbohydrates, inorganic ions, lipids, enzymes, and other molecular compounds. It is the site of most cellular processes as it houses the organelles that make up the endomembrane system , as well as those that stand alone. The endoplasm is necessary for most metabolic activities, including cell division .
34-446: Sister: Amoebozoa Obazoa is a proposed sister clade of Amoebozoa (which together form Amorphea ). The term Obazoa is based on the OBA acronym for O pisthokonta , B reviatea , and A pusomonadidae , the group's three constituent clades . Determining the placement of Breviatea and Apusomonadida and their properties is of interest for the development of the opisthokonts in which
68-410: A "monopodial" form, with the entire cell functioning as a single pseudopod. Large pseudopods may produce numerous clear projections called subpseudopodia (or determinate pseudopodia ), which are extended to a certain length and then retracted, either for the purpose of locomotion or food intake. A cell may also form multiple indeterminate pseudopodia, through which the entire contents of the cell flow in
102-512: A high-level taxon , named Amorphea . Amoebozoa includes many of the best-known amoeboid organisms, such as Chaos , Entamoeba , Pelomyxa and the genus Amoeba itself. Species of Amoebozoa may be either shelled (testate) or naked, and cells may possess flagella . Free-living species are common in both salt and freshwater as well as soil, moss and leaf litter. Some live as parasites or symbionts of other organisms, and some are known to cause disease in humans and other organisms. While
136-586: A large amount of proteins or breakdown a lot of material require a large amount of mitochondria. Glucose is broken down through three sequential processes: glycolysis , the citric acid cycle , and the electron transport chain . Protein synthesis begins at the ribosome , both free ones and those bound to the rough endoplasmic reticulum . Each ribosome is composed of 2 subunits and is responsible for translating genetic codes from mRNA into proteins by creating strings of amino acids called peptides . Proteins are usually not ready for their final target after leaving
170-509: A more suitable name for a clade of approximately the same composition, a sister group to the Diaphoretickes . More recent work places the members of Amorphea together with the malawimonids and collodictyonids in a proposed clade called Opimoda, which comprises one of two major lineages diverging at the root of the eukaryote tree of life, the other being Diphoda . Traditionally all amoebozoa with lobose pseudopods were grouped together in
204-455: A phospholipid bilayer and can fuse with other organelles as well as the plasma membrane. Their membrane is only semipermeable and allows them to house substances that could be harmful to the cell if they were allowed to flow freely within the cytosol. These granules give the cell a large amount of regulation and control over the wide variety of metabolic activities that take place within the endoplasm. There are many different types, characterized by
238-400: A posterior bulb called a uroid, which may serve to accumulate waste, periodically detaching from the rest of the cell. When food is scarce, most species can form cysts , which may be carried aerially and introduce them to new environments. In slime moulds, these structures are called spores, and form on stalked structures called fruiting bodies or sporangia . Mixotrophic species living in
272-531: A symbiotic relationship with microalgae of the genus Chlorella , which lives inside the cytoplasm of their host, have been found in Arcellinida and Mayorella . The majority of Amoebozoa lack flagella and more generally do not form microtubule -supported structures except during mitosis . However, flagella do occur among the Archamoebae , and many slime moulds produce biflagellate gametes . The flagellum
306-423: Is a large and diverse group, but certain features are common to many of its members. The amoebozoan cell is typically divided into a granular central mass, called endoplasm , and a clear outer layer, called ectoplasm. During locomotion, the endoplasm flows forwards and the ectoplasm runs backwards along the outside of the cell. In motion, many amoebozoans have a clearly defined anterior and posterior and may assume
340-491: 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 classification schemes, Amoebozoa is usually ranked as a phylum within either the kingdom Protista or the kingdom Protozoa . In the classification favored by the International Society of Protistologists, it
374-421: Is assisted by appendages like flagella and cilia, the main source of movement in these cells is pseudopodial locomotion. This process takes advantage of the different consistencies of the endoplasm and ectoplasm to create a pseudopod. Pseudopod , or “false foot” is the term for the extension of a cell's plasma membrane into what appears to be an appendage that pulls the cell forward. The process behind this involves
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#1732895811175408-486: Is generally anchored by a cone of microtubules, suggesting a close relationship to the opisthokonts . The mitochondria in amoebozoan cells characteristically have branching tubular cristae. However, among the Archamoebae , which are adapted to anoxic or microaerophilic habitats, mitochondria have been lost. It appears (based on molecular genetics) that the members of Amoebozoa form a sister group to animals and fungi, diverging from this lineage after it had split from
442-502: 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
476-700: The Lobosa are paraphyletic: Conosa is sister of the Cutosea. Centramoebida Himatismenida Himatismenida Thecamoebida Dermamoebida Vannellida Dactylopodida Trichosida Microcoryciidae Echinamoebida Leptomyxida Euamoebida Arcellinida Squamocutida Entamoebida Pelobiontida Phalansteriida Flamellidae Ramamoebida Profiliida Fractovitellida Acytosteliales Dictyosteliida Ceratiomyxida Protosporangiida Cribrariales Reticulariales Liceida Trichiida Endoplasm The endoplasm, like
510-502: The class Lobosea , placed with other amoeboids in the phylum Sarcodina or Rhizopoda , but these were considered to be unnatural groups. Structural and genetic studies identified the percolozoans and several archamoebae as independent groups. In phylogenies based on rRNA their representatives were separate from other amoebae, and appeared to diverge near the base of eukaryotic evolution, as did most slime molds. However, revised trees by Cavalier-Smith and Chao in 1996 suggested that
544-475: The classic Lobosea: non-flagellated amoebae with blunt, lobose pseudopods ( Amoeba , Acanthamoeba, Arcella, Difflugia etc. ). The latter is made up of both amoeboid and flagellated cells, characteristically with more pointed or slightly branching subpseudopodia (Archamoebae and the Mycetozoan slime molds). From older studies by Cavalier-Smith, Chao & Lewis 2016 and Silar 2016. Also recent phylogeny indicates
578-400: The cytoplasm, is far from static. It is in a constant state of flux through intracellular transport , as vesicles are shuttled between organelles and to/from the plasma membrane. Materials are regularly both degraded and synthesized within the endoplasm based on the needs of the cell and/or organism. Some components of the cytoskeleton run throughout the endoplasm though most are concentrated in
612-406: The direction of locomotion. These are more or less tubular and are mostly filled with granular endoplasm. The cell mass flows into a leading pseudopod, and the others ultimately retract, unless the organism changes direction. While most amoebozoans are "naked," like the familiar Amoeba and Chaos , or covered with a loose coat of minute scales, like Cochliopodium and Korotnevella , members of
646-405: The ectoplasm - towards the cells edges, closer to the plasma membrane. The endoplasm's granules are suspended in cytosol. The term granule refers to a small particle within the endoplasm, typically the secretory vesicles . The granule is the defining characteristic of the endoplasm, as they are typically not present within the ectoplasm. These offshoots of the endomembrane system are enclosed by
680-429: The efficiency of eukaryotes. These organelles breakdown simple sugars like glucose to create a multitude of ATP ( adenosine triphosphate ) molecules. ATP provides the energy for protein synthesis, which takes about 75% of the cell's energy, as well as other cellular processes like signaling pathways. Present in a cell's endoplasm, the number of mitochondria varies based on the cell's metabolic needs. Cells that must make
714-402: The endomembrane system and the plasma membrane. In addition to these 2 main processes, there are many other activities that take place in the endoplasm. Lysosomes degrade waste and toxins with the enzymes they contain. Smooth endoplasmic reticulum makes hormones and lipids, degrades toxins, and controls cellular levels of calcium. Though most control of cell division is present in the nucleus,
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#1732895811175748-404: The gel of the ectoplasm, and sol , more fluid, portion of the endoplasm. To create the pseudopod, the gel of the ectoplasm begins to convert to sol which, along with the endoplasm, pushes a portion of the plasma membrane into an appendage. Once the pseudopod is extended, the sol within begins to peripherally convert back to gel, converting back to the ectoplasm as the lagging cell body flows up into
782-464: The largest protozoa. The well-known species Amoeba proteus , which may reach 800 μm in length, is often studied in schools and laboratories as a representative cell or model organism , partly because of its convenient size. Multinucleate amoebae like Chaos and Pelomyxa may be several millimetres in length, and some multicellular amoebozoa, such as the "dog vomit" slime mold Fuligo septica , can cover an area of several square meters. Amoebozoa
816-573: The main lineages of animals and fungi emerged. The relationships among opisthokonts, breviates and apusomonads are not conclusively resolved (as of 2018), though Breviatea is usually inferred to be the most basal of the three lineages. The phylogeny of the Obazoa is shown in the cladogram. Diaphoretickes (inc. plants) Discoba Ancyromonadida Malawimonada CRuMs Amoebozoa Breviatea Apusomonadidae Holomycota (inc. fungi) Holozoa (inc. animals) Amoebozoa Amoebozoa
850-424: The majority of amoebozoan species are unicellular, the group also includes several clades of slime molds , which have a macroscopic, multicellular stage of life during which individual amoeboid cells remain together after multiple cell division to form a macroscopic plasmodium or, in cellular slime molds, aggregate to form one. Amoebozoa vary greatly in size. Some are only 10–20 μm in diameter, while others are among
884-468: The name "unikonts" (formally, Unikonta) for this branch, whose members were believed to have been descended from a common ancestor possessing a single emergent flagellum rooted in one basal body . However, while the close relationship between Amoebozoa and Opisthokonta is robustly supported, recent work has shown that the hypothesis of a uniciliate ancestor is probably false. In their Revised Classification of Eukaryotes (2012), Adl et al. proposed Amorphea as
918-619: The order Arcellinida form rigid shells, or tests , equipped with a single aperture through which the pseudopods emerge. Arcellinid tests may be secreted from organic materials, as in Arcella , or built up from collected particles cemented together, as in Difflugia . In all amoebozoa, the primary mode of nutrition is phagocytosis , in which the cell surrounds potential food particles with its pseudopods, sealing them into vacuoles within which they may be digested and absorbed. Some amoebozoans have
952-404: The other groups, as illustrated below in a simplified diagram: Loukozoa [REDACTED] CRuMs [REDACTED] Amoebozoa Breviata [REDACTED] Apusomonadida [REDACTED] Fungi [REDACTED] Animalia [REDACTED] Strong similarities between Amoebozoa and Opisthokonts lead to the hypothesis that they form a distinct clade. Thomas Cavalier-Smith proposed
986-452: The pseudopod moving the cell forward. Though research has shown aspects of the cytoskeleton (specifically microfilaments ) assist with pseudopod formation, the exact mechanism is unknown. Research on the shelled amoeba Difflugia demonstrated that microfilaments lie both parallel and perpendicular to the axis of contraction of the plasma membrane to assist with plasma membrane extension into an appendage. The mitochondria are vital to
1020-669: The remaining lobosans do form a monophyletic group, to which the Archamoebae and Mycetozoa were closely related, although the percolozoans were not. Subsequently, they emended the phylum Amoebozoa to include both the subphylum Lobosa and a new subphylum Conosa , comprising the Archamoebae and the Mycetozoa . Recent molecular genetic data appear to support this primary division of the Amoebozoa into Lobosa and Conosa. The former, as defined by Cavalier-Smith and his collaborators, consists largely of
1054-562: The ribosome. Ribosomes attached to endoplasmic reticulum release their protein chains into the lumen of the endoplasmic reticulum, which is the beginning of the endomembrane system. Within the ER the proteins are folded and modified by the addition of molecules like carbohydrates, then are sent to the Golgi apparatus , where they are further modified and packaged to be sent to their final destination. Vesicles are responsible for transport in between components of
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1088-465: The ribosomes responsible for protein synthesis. Cytosol contains predominantly water, but also has a complex mixture of large hydrophilic molecules, smaller molecules and proteins, and dissolved ions. The contents of the cytosol change based on the needs of the cell. Not to be confused with the cytoplasm, the cytosol is only the gel matrix of the cell which does not include many of the macromolecules essential to cellular function. Though amoeba locomotion
1122-468: The semifluid portion of the endoplasm, in which materials are suspended. It is a concentrated aqueous gel with molecules so crowded and packed together within the water base that its behavior is more gel-like than liquid. It is water based but contains both small and large molecules, giving it density. It has several functions, including physical support of the cell, preventing collapse, as well as degrading nutrients, transport of small molecules, and containing
1156-467: The substance that the vesicle contains. These granules/vesicles can contain enzymes, neurotransmitters, hormones, and waste. Typically the contents are destined for another cell/tissue. These vesicles act as a form of storage and release their contents when needed, often prompted by a signaling pathway. Once signaled to move, the vesicles can travel along aspects of the cytoskeleton via motor proteins to reach their final destination. The cytosol makes up
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