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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 ...
In asymptomatic infections, the amoeba lives by eating and digesting bacteria and food particles in the gut, a part of the gastrointestinal tract. [9] It does not usually come in contact with the intestine itself due to the protective layer of mucus that lines the gut. Disease occurs when amoeba comes in contact with the cells lining the intestine.
These pseudopodia can be as long as three times the diameter of the cell body and may be branched or unbranched. [6] The pseudopodia may accumulate in the direction in which the organism moves. [3] Shorter, slow moving, pin-like pseudopodia are projected and withdrawn very quickly from the cell body in addition to having longer pseudopodia.
The cell's overall shape may change rapidly as pseudopodia are extended and retracted into the cell body. An Amoeba may produce many pseudopodia at once, especially when freely floating. When crawling rapidly along a surface, the cell may take a roughly monopodial form, with a single dominant pseudopod deployed in the direction of movement.
They can change their shape by extending and retracting these pseudopods. [14] Amoeba: Found in every major protist lineage. Amoeboid cells occur among the protozoans, but also in the algae and the fungi. [15] [16] Not motile
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
Some examples of organisms that exhibit this type of locomotion are amoebae (such as Amoeba proteus and Naegleria gruberi, [2]) and slime molds, as well as some cells in humans such as leukocytes. Sarcomas , or cancers arising from connective tissue cells, are particularly adept at amoeboid movement, thus leading to their high rate of metastasis .
An amoeba of the genus Mayorella (Amoebozoa, Discosea). Amoebozoa 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.