flagellaliike

Flagellaliike refers to locomotion produced by flagella, slender cellular extensions that propel cells through liquids. The term covers both prokaryotic flagella and eukaryotic flagella, which differ in structure, energy source, and mode of motion.

In prokaryotes, flagella are external, helical filaments anchored in a basal motor embedded in the cell envelope. The motor uses energy from a proton motive force or, in some organisms, a sodium gradient to rotate the flagellum like a rotary propeller. The direction and speed of rotation produce distinct swimming patterns: runs, when the flagellum rotates in one direction, and tumbles, when rotation changes to reorient the cell. Flagellar arrangement varies, including monotrichous (single flagellum), lophotrichous (tufts at one end), amphitrichous (flagella at both ends), and peritrichous (distributed over the cell surface).

In eukaryotes, flagella are whip-like extensions built from a 9+2 arrangement of microtubules in the axoneme. They beat through coordinated bending motions driven by dynein motors that slide microtubules against each other, powered by ATP. Eukaryotic flagella are typically longer and fewer in number than bacterial flagella and include the tails of sperm cells as well as flagellated algae and some protozoa. This beating generates propulsion rather than simple rotation.

Flagellar motility is often integrated with sensing and navigation, enabling chemotaxis, phototaxis, or aerotaxis toward favorable conditions. Flagellin, the main protein of bacterial flagella, can also act as a pathogen-associated molecule recognized by host immune systems, linking flagellaliike to both ecology and health. Examples of flagellated organisms span bacteria such as Escherichia coli, archaea with archaella, and a variety of eukaryotes including sperm and algal cells.