Concept
Bacterial flagella
Rotary appendages for motility
fluh-JEL-uh
High-yield clue
Flagella provide motility and their flagellin protein is the H antigen used in serotyping.
Overview
Long helical protein filaments driven by a rotary motor that propel bacteria and enable directed movement (chemotaxis) toward or away from stimuli. Their protein (flagellin) is the basis of the H antigen used in serotyping.
Classification
- Helical protein filament
- Rotary basal-body motor
- Flagellin subunits
- Arrangement patterns vary
Lab & identification clues
- H (flagellar) antigen vocabulary
- Monotrichous/peritrichous arrangement concept
- Motility-test interpretation vocabulary
Associations
- Chemotaxis toward nutrients
- Swarming motility vocabulary
- Serotyping by H antigen
Commonly confused with
- Pili/fimbriae
- Axial filament (spirochete)
Your notes
Original microbiology concept summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC/WHO topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment selection, infection-control instructions, or specimen-handling guidance.