Wednesday 14 November 2012

Amoeba


The cell's organelles and cytoplasm are enclosed by a cell membrane; it obtains its food throughphagocytosis. This makes amoebae heterotrophs. Amoebae have a single large tubular pseudopod at the anterior end, and several secondary ones branching to the sides. The most famous species,Amoeba proteus, averages about 220-740 μm in length, while in motion .making it a giant amongamoeboids A few amoeboids belonging to different genera can grow larger, however, such as Gromia,Pelomyxa, and Chaos.
Amoebae's most recognizable features include one or more nuclei and a simple contractile vacuole to maintain osmotic equilibrium - low water amounts in cell protecting cell from bursting with excess water.. Food enveloped by the amoeba is stored and digested in vacuoles. Amoebae, like other unicellular eukaryotic organisms, reproduce asexually via mitosis and cytokinesis, not to be confused with binary fission, which is how prokaryotes (bacteria) reproduce. In cases where the amoeba are forcibly divided, the portion that retains the nucleus will survive and form a new cell and cytoplasm, while the other portion dies. Amoebae also have no definite shape.[

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