Undulipodium

An undulipodium or 9+2 organelle is an extracellular projection of a eukaryotic cell containing a microtubule array. Both flagella and cilia are considered undulipodia and are similar structurally, however each differs functionally. Flagella use a whip-like action to create movement of the whole cell, such as the movement of sperm in the reproductive tract, and also create water movement as in the choanocytes of sponges. Cilia are more numerous, move in a waving action, and are responsible for movement in organisms such as ciliates and Platyhelminthes, but also move extracellular substances in animals, such as the ciliary escalator found in the respiratory tract and the corona of rotifers. Cilia may also function as sensory organs.

Undulipodia are an extension of the cell membrane containing both cytoplasm and a regular arrangement of microtubules known as an axoneme. At the base of the extension lies a structure called the "kinetosome" or "basal body" which is attached via motor proteins to the microtubules. The kinetosome mediates movement through a chemical reaction, causing the microtubules to slide against one another and the whole structure to bend.


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  • Undulipodium — Darstellung von Zilien unter dem Elektronenmikroskop. Sichtbar ist die 9x2+2 Struktur. Als Zilie oder Cilium (lat., n.; auch Kinozilie, Flimmerhärchen, Wimper) bezeichnet man 5–10 µm lange und 250 nm dicke Zytoplasmafortsätze von eukaryotischen… …   Deutsch Wikipedia

  • undulipodium — noun /ˌʌn.djə.ləˈpəʊ.di.əm,ˌʌn.djʊ.ləˈpəʊ.di.əm,ˌʌn.dʒə.ləˈpoʊ.di.əm,ˌʌn.djʊ.ləˈpoʊ.di.əm/ An intracellular projection of a eukaryotic cell containing a microtubule array, used for locomotion or for propelling fluids. See Also: pseudopodium,… …   Wiktionary

  • undulipodium — A flexible whiplike intracellular extension of many eukaryotic cells, with a characteristic nine fold symmetry, an arrangement of nine paired peripheral microtubules and one central pair, often termed 9 + 2 symmetry; it appears to grow out from a …   Medical dictionary

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  • Cell membrane — Illustration of a Eukaryotic cell membrane The cell membrane or plasma membrane is a biological mem …   Wikipedia

  • Centriole — Schematic of centriole showing microtubule triplets Three dimensi …   Wikipedia

  • Golgi apparatus — This article is about the organelle. For the Phish song, see Junta (album). Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. Numerous circular vesicles can be seen in proximity to the organelle …   Wikipedia

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