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The term organelle (Italian organella, ‘little organ’), in the life sciences, describes each of the discrete parts into which a living cell may be divided. Many organelles are partitioned from the interior of the cell by membranes surrounding them, as membrane surround cells. Organelles have specialized functions within the cells, such as energy transduction or motility. Possession of organelles is a characteristic of the more complex living cells which make up multicellular plants and animals, and single-celled protozoa. Such cells are termed eukaryotic, while the simpler cells of bacteria possess no organelles and are called prokaryotic. Some biologists have suggested that eukaryotic cells may have originated as associations (symbioses) of several prokaryotes and that this symbiosis, over time, became permanent, giving rise to organelles. RB
See also cytology. |
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