Flagellum

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(Redirected from Flagellar)

Flagellum is a whip-like structure that allows a cell to move. They are found in all three domains of the cellular world: Bacteria, Archaea, and Eukarya.

Structure[edit | edit source]

In bacteria, the flagellum is a complex rotating structure driven by a molecular motor at the base. In eukaryotes, it is a complex bending structure driven by molecular motors that slide microtubules.

Function[edit | edit source]

Flagella are primarily used for cell movement. They are not fast enough to allow bacteria and sperm to swim against a current, but they can allow a cell to move in a particular direction in a liquid medium.

Types[edit | edit source]

There are three types of flagella: bacterial, archaeal, and eukaryotic.

Bacterial[edit | edit source]

The bacterial flagellum is made up of the protein flagellin. Its shape is a 20 nanometer-thick hollow tube. It is helical and has a sharp bend just outside the outer membrane; this "hook" allows the axis of the helix to point directly away from the cell.

Archaeal[edit | edit source]

Archaeal flagella are a different structure which has a similar function and overall appearance to bacterial flagella, but are not homologous.

Eukaryotic[edit | edit source]

Eukaryotic flagella are complex cellular projections that lash back and forth. Unlike bacterial flagella, they are composed of a bundle of nine fused pairs of microtubule doublets surrounding two central single microtubules.

See Also[edit | edit source]

Flagellum Resources
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Contributors: Prab R. Tumpati, MD