Flagellum

013005 Groups of cells creep or glide as an aggregate unit 

013040 Cells glide on concave or ventral side on solid 

A single flagellum is located at each pole. Several flagella are located at 1 pole. 

Several flagella are located at both poles. Flagella are sub-polar. 

A single flagellum is located near the pole. Several flagella are located near the pole. Flagellum (or flagella) is (are) inserted frankly laterally (from the middle of the cell). 

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Certain proteins endow cells with unique capabilities for movement. Cell division, muscle contraction, and cell motility represent some of the ways in which cells execute motion. The contractile and motile proteins underlying these motions share a common property they are filamentous or polymerize to form filaments. Examples include actin and myosin, the filamentous proteins forming the contractile systems of cells, and tubulin, the major component of microtubules (the filaments involved in the mitotic spindle of cell division as well as in flagella and cilia). Another class of proteins involved in movement includes dynein and kinesin, so-called motor proteins that drive the movement of vesicles, granules, and organelles along microtubules serving as established cytoskeletal tracks. ... 

A Proton Gradient Drives die Rotation of Bacterial Flagella... 

FIGURE 17.1 Micrographs and electron micrographs of cytoskeletal elements, cilia, and flagella (a) microtnbnles, (b) rat sperm tail microtnbnles (cross-section),... 

Microtubules Are the Fundamental Structural Units of Cilia and Flagella... 

As already noted, microtubules are also the fundamental building blocks of cilia and flagella. Cilia are short, cylindrical, hairlike projections on the surfaces of the cells of many animals and lower plants. The beating motion of cilia functions either to move cells from place to place or to facilitate the movement of extracellular fluid over the cell surface. Flagella are much longer structures found singly or a few at a time on certain cells (such as sperm cells). They pro-... 

Some specialized eukaryotic cells have cilia that show a whiplike motion. Sperm cells move with one flagella, which is much longer than a cilium but has a nearly identical internal structure called axoneme. It is composed of nine doublet MTs that form a ring around a pair of single MTs. Numerous proteins bind to the MTs. Ciliary dynein motors generate the force by which MTs slide along each other to cause the bending of the axoneme necessary for motion. 

In general, movement is an intrinsic property of living creatures. It occurs at different structural levels, including ion transfer through membranes, separation of replicated chromosomes, beating of cilia and flagella or, the most common, contraction of muscles. These contractions enable... 

When tubulin heterodimers are assembled into microtubules, they form linear protofilaments with the P-tubulin subunit of one tubulin molecule linking covalently with the a-subunit of the next. Direct examination by electron microscopy of tannic acid-treated specimens has shown that micrombules in neurons and the A-microtubules of cilia and flagella have 13 protofilaments arranged side to side to form a cylinder around what appears to be an empty lumen. 

The force-producing MAPs (kinesin, dynein, and dynamin) function as energy-transducing ATPases to provide the motive force for cilia and flagella by means of... 

Parallel arrays of microtubules are found in the axoneme of cilia and flagella of eukaryotic cells, and these are of constant pattern throughout the phylogenetic scale. 

Other lateral structures that are bound to the microtubules of cilia and flagella are filamentous interdoublet links composed of nexin, radial spokes directed to the central pair of microtubules, and a central sheath that is attached to the walls of the central pair (Figure 1). 

Microtubules, an integral component of the cellular cy-toskeleton, consist of cytoplasmic tubes 25 nm in diameter and often of extreme length. Microtubules are necessary for the formation and function of the mitotic spindle and thus are present in all eukaryotic cells. They are also involved in the intracellular movement of endocytic and exocytic vesicles and form the major structural components of cilia and flagella. Microtubules are a major component of axons and dendrites, in which they maintain structure and participate in the axoplasmic flow of material along these neuronal processes. 

An absence of dynein in cilia and flagella results in immotile cilia and flagella, leading to male sterility and chronic respiratory infection, a condition known as Kartagener syndrome. 

Three types of thread-like appendages may be found growing from bacterial cells flagella, pili (fimbriae) and F-pili (sex strands). 

Flagella are threads of protein often 2fim. long which start as small basal organs just beneath the cytoplasmic membrane. They are responsible for the movement of motile bacteria. Their number and distribution varies. Some species bear a single flagellum, others are flagellate over their whole surface. 

Bacterial motion is generally associated with the presence of organs of locomotion known as flagella (singular, flagellum). They were first observed in stained preparations by Cohn. The presence of flagella does not mean necessarily that the organisms are always motile, but it indicates a potential power to move. 

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