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How do bacterial flagella differ from eukaryotic flagella?
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Bacterial and eukaryotic flagella are distinct structures that facilitate cell motility through fundamentally different mechanisms.1
Structural Differences
- Composition: Eukaryotic flagella are complex structures composed of microtubules arranged in a "nine-plus-two" pattern, made of the protein tubulin. In contrast, bacterial flagella are simpler, helical filaments constructed from a single type of protein called flagellin.12
- Anchoring: Eukaryotic flagella are anchored by a basal body and move in a whiplike fashion. Bacterial flagella are attached to a basal body within the cell membrane that functions like a turbine.12
Functional Differences
- Motion: Eukaryotic flagella move with a characteristic whiplike motion. Bacterial flagella rotate like a propeller, with the direction of rotation determining whether the bacterium swims in a straight line or tumbles.12
- Energy Source: Eukaryotic flagella rely on adenosine triphosphate (ATP) for energy. Bacterial flagella derive their energy from the proton-motive force, or an ion gradient, across the cell membrane.12