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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 ...
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.
Food enveloped by the Amoeba is stored in digestive organelles called food vacuoles. Amoeba, like other unicellular eukaryotic organisms, reproduces asexually by mitosis and cytokinesis. Sexual phenomena have not been directly observed in Amoeba, although sexual exchange of genetic material is known to occur in other Amoebozoan groups. [15]
The Archamoebae are a group of protists originally thought to have evolved before the acquisition of mitochondria by eukaryotes. [1] They include genera that are internal parasites or commensals of animals (Entamoeba and Endolimax). A few species are human pathogens, causing diseases such as amoebic dysentery.
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]
They have different life cycles, trophic levels, modes of locomotion, and cellular structures. [4] [5] Although most protists are unicellular, there is a considerable range of multicellularity amongst them; some form colonies or multicellular structures visible to the naked eye.
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.
This mRNA is then transported out of the nucleus, where it is translated into a specific protein molecule. The nucleolus is a specialized region within the nucleus where ribosome subunits are assembled. In prokaryotes, DNA processing takes place in the cytoplasm. [2] Mitochondria and chloroplasts: generate energy for the cell.