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The prokaryotic flagellum uses a rotary motor, and the eukaryotic flagellum uses a complex sliding filament system. Eukaryotic flagella are ATP-driven, while prokaryotic flagella can be ATP-driven (Archaea) or proton-driven (Bacteria). [11] The three types of flagella are bacterial, archaeal, and eukaryotic.
As such, the type three secretory system supports the hypothesis that the flagellum evolved from a simpler bacterial secretion system. However, the true relationship could be the reverse: recent phylogenetic research strongly suggests the type three secretory system evolved from the flagellum through a series of gene deletions. [7]
Flagellins are a family of proteins present in flagellated bacteria [1] which arrange themselves in a hollow cylinder to form the filament in a bacterial flagellum. Flagellin has a mass on average of about 40,000 daltons. [2] [3] Flagellins are the principal component of bacterial flagella that have a crucial role in bacterial motility.
Flagella in eukaryotes are supported by microtubules in a characteristic arrangement, with nine fused pairs surrounding two central singlets. These arise from a basal body. In some flagellates, flagella direct food into a cytostome or mouth, where food is ingested. Flagella role in classifying eukaryotes.
Eukaryotic flagella are complex cellular projections that lash back and forth, rather than in a circular motion. Prokaryotic flagella use a rotary motor, and the eukaryotic flagella use a complex sliding filament system. Eukaryotic flagella are ATP-driven, while prokaryotic flagella can be ATP-driven (archaea) or proton-driven (bacteria). [22]
The bacterial flagellum is made of about 20 proteins, with approximately another 30 proteins required for its regulation and assembly. [146] The flagellum is a rotating structure driven by a reversible motor at the base that uses the electrochemical gradient across the membrane for power. [147]
The bacterial flagellum stretches from cytoplasm through the cell membrane(s) and extrudes through the cell wall. They are long and thick thread-like appendages, protein in nature. A different type of flagellum is found in archaea and a different type is found in eukaryotes.
Many bacteria, such as Vibrio, are monoflagellated and have a single flagellum at one pole of the cell. Their method of chemotaxis is different. Others possess a single flagellum that is kept inside the cell wall. These bacteria move by spinning the whole cell, which is shaped like a corkscrew. [25] [page needed]