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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 Amoeba, the pseudopodia are approximately tubular, and rounded at the ends (lobose). 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 ...
However, flagella do occur among the Archamoebae, and many slime moulds produce biflagellate gametes [citation needed]. The flagellum is generally anchored by a cone of microtubules, suggesting a close relationship to the opisthokonts. [citation needed] The mitochondria in amoebozoan cells characteristically have branching tubular cristae.
The endosymbiotic theory holds that mitochondria and chloroplasts have bacterial origins. Both organelles contain their own sets of DNA and have bacteria-like ribosomes. It is likely that modern mitochondria were once a species similar to Rickettsia, with the parasitic ability to enter a cell. [33]
Amoeba proteus is a large species of amoeba closely related to another genus of giant amoebae, Chaos. As such, the species is sometimes given the alternative scientific name Chaos diffluens. [1] [2] Amoeba proteus in locomotion. This protozoan uses extensions called pseudopodia to move and to eat smaller unicellular organisms.
One hypothesis for the origin of multicellularity is that a group of function-specific cells aggregated into a slug-like mass called a grex, which moved as a multicellular unit. This is essentially what slime molds do. Another hypothesis is that a primitive cell underwent nucleus division, thereby becoming a coenocyte.
The spongiome serves several functions in water transport into the contractile vacuole and in localization and docking of the contractile vacuole within the cell. Paramecium and Amoeba possess large contractile vacuoles (average diameter of 13 and 45 μm, respectively), which are relatively comfortable to isolate, manipulate and assay.
The Amoebidae are a family of Amoebozoa, [1] including naked amoebae that produce multiple pseudopodia of indeterminate length. These are roughly cylindrical with granular endoplasm and no subpseudopodia, as found in other members of the class Tubulinea.