Which structure is used by motile bacteria to move?

Which structure is used by motile bacteria to move?

• A. Flagella
• B. Cilia
• C. Pili
• D. Microvilli

Answer: (A)

Motility in bacteria is driven by flagella. These are long, whip-like structures that rotate like tiny propellers, powered by a motor anchored in the cell membrane. This rotation pushes the cell through liquid, and bacteria can switch between running and tumbling to navigate toward favorable conditions. The energy for rotation comes from the proton motive force across the membrane. Cilia and microvilli belong to eukaryotic cells, not bacteria, and are not used for bacterial movement. Pili are mainly for attachment or genetic exchange; some pili can enable limited surface movement (twitching), but the classic swimming motion through liquid is accomplished by flagella.

Motility in bacteria is driven by flagella. These are long, whip-like structures that rotate like tiny propellers, powered by a motor anchored in the cell membrane. This rotation pushes the cell through liquid, and bacteria can switch between running and tumbling to navigate toward favorable conditions. The energy for rotation comes from the proton motive force across the membrane.

Cilia and microvilli belong to eukaryotic cells, not bacteria, and are not used for bacterial movement. Pili are mainly for attachment or genetic exchange; some pili can enable limited surface movement (twitching), but the classic swimming motion through liquid is accomplished by flagella.