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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 ...
Cells are broadly categorized into two types: eukaryotic cells, which possess a nucleus, and prokaryotic cells, which lack a nucleus but have a nucleoid region. Prokaryotes are single-celled organisms such as bacteria , whereas eukaryotes can be either single-celled, such as amoebae , or multicellular , such as some algae , plants , animals ...
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.
Anatomy of an Amoeba. Species of Amoeba move and feed by extending temporary structures called pseudopodia. These are formed by the coordinated action of microfilaments within the cellular cytoplasm pushing out the plasma membrane which surrounds the cell. [11] In Amoeba, the pseudopodia are approximately tubular, and rounded at the ends ...
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]
The cell nucleus (from Latin nucleus or nuculeus ' kernel, seed '; pl.: nuclei) is a membrane-bound organelle found in eukaryotic cells.Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many.
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 most common examples of obligate endosymbiosis are mitochondria and chloroplasts; however, they do not reproduce via mitosis in tandem with their host cells. Instead, they replicate via binary fission, a replication process uncoupled from the host cells in which they reside.