Identify the structure and function of bacterial flagella

Flagella

-responsible for movement -long, propeller-like structures that extend beyond surface of cell -for prokaryotes, these are rigid, protein helices that rotate 360 degrees

Flagella Structure

-composed of filament, hook and basal body -flagellin proteins (filament) arranged in chains and form helix around hollow core -base of filament inserts into hook -basal body anchors filament and hook to cell wall by a rod and series of two or four rings -filament capable of rotating 360

Internal Flagella

-helical types of cells with corkscrew fashioned cytoplasm with bundles of flagella inside (endoflagella/axial filaments) that rotate against each other and rotate around the cell -spiraling type of corkscrew motility, helps with penetrating tissue -ex: syphilis and Borrelia burgdorferi (Lyme disease)

Function of Flagella

-rotation propels bacterium through enviroment -rotation can be clockwise or counterclockwise; reversible -prokaryotes move in response to stimuli (taxis). For cells with multiple flagella: runs: movements of a cell in a single direction for some time; increase with favorable stimuli (positive chemotaxis, phototaxis or aerotaxis)[counterclockwise] tumbles: abrupt, random, changes in direction; increase with unfavorable stimuli (negative chemotaxis or phototaxis)[clockwise]

Arrangement of Flagella

monotrichous: single, polar flagellum amiphitrichous: flagella on both ends peritrichous: flagella all around particular cell lophotrichous: tuft of flagella on one end of the cell