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Clockwise from top right: Amoeba proteus, Actinophrys sol, Acanthamoeba sp., Nuclearia thermophila., Euglypha acanthophora, neutrophil ingesting bacteria. An amoeba (/ ə ˈ m iː b ə /; less commonly spelled ameba or amœba; pl.: amoebas (less commonly, amebas) or amoebae (amebae) / ə ˈ m iː b i /), [1] often called an amoeboid, is a type of cell or unicellular organism with the ability ...
An amebocyte or amoebocyte (/əˈmiː.bə.saɪt/) is a motile cell (moving like an amoeba) in the bodies of invertebrates including cnidaria, echinoderms, molluscs, tunicates, sponges, and some chelicerates. Moving by pseudopodia, amebocytes can manifest as blood cells or play a similar biological role.
Amoeboid movement is the most typical mode of locomotion in adherent eukaryotic cells. [1] It is a crawling-like type of movement accomplished by protrusion of cytoplasm of the cell involving the formation of pseudopodia ("false-feet") and posterior uropods.
The functions of pseudopodia include locomotion and ingestion: Pseudopodia are critical in sensing targets which can then be engulfed; the engulfing pseudopodia are called phagocytosis pseudopodia. A common example of this type of amoeboid cell is the macrophage. They are also essential to amoeboid-like locomotion.
Microfilament functions include cytokinesis, amoeboid movement, cell motility, changes in cell shape, endocytosis and exocytosis, cell contractility, and mechanical stability. Microfilaments are flexible and relatively strong, resisting buckling by multi-piconewton compressive forces and filament fracture by nanonewton tensile forces.
It is thought that the chromatoidal body formation is a manifestation of parasite-host adaptive conditions. Ribonucleoprotein is synthesized under favorable conditions, crystallized in the resistant cyst stage and dispersed in the newly excysted amoebae when the amoeba is able to establish itself in a new host. [1]
During locomotion one pseudopod typically becomes dominant and the others are retracted as the body flows into it. In some cases the cell moves by "walking", with relatively permanent pseudopodia serving as limbs. The most important genera are Amoeba and Chaos, which are set apart from the
Shown is a micrograph of an amoeba; the darker pink nucleus is central to the eukaryotic cell, with the majority of the rest of the cell's body belonging to the endoplasm. Though not visible, the ectoplasm resides directly internal to the plasma membrane. Endoplasm generally refers to the inner (often granulated), dense part of a cell's cytoplasm.