Final answer:
Bacterial flagella are powered by a proton gradient across the cell membrane, rather than ATP hydrolysis, differing from eukaryotic flagella which utilize ATP to enable their whip-like motion.
Step-by-step explanation:
The eubacterial flagellum is a complex structure that provides motility to bacterial cells by utilizing a rotating mechanism powered by a proton gradient across the cell membrane, not ATP hydrolysis. In bacteria, the rotation of the flagellum is driven by a proton flow through a specialized structure that functions as both a proton gate and a molecular motor. This is distinct from the way in which eukaryotic flagella operate, which do use ATP hydrolysis, involving dynein motor proteins and a flexible whip-like motion caused by the sliding of microtubules against each other. Unlike the flagella of eukaryotic cells that require ATP to function, as seen in experiments with isolated axonemes that 'beat' in the presence of ATP, bacterial flagella are directly powered by the proton motive force created by the bacterial cell membrane.