Cell motility is the capacity of a cell to generate its own directed movement, distinguished from passive displacement by bulk fluid transport, and it is essential to embryonic tissue formation and to immune function in the adult organism. Human cells achieve motility by mechanistically distinct means: flagellar propulsion, in which a tail built of polymerized microtubule monomers is bent by dynein cross-linking proteins to whip and drive the cell forward; and crawling, for which two competing models are proposed — the cytoskeletal model, where rapid actin polymerization extends a leading edge while microtubules serve alternately as steering rudder or immobilizing anchor depending on whether they are in a dynamic or fixed state, and the membrane flow model, where membrane is endocytosed from around the cell and re-exocytosed at the front, with integrin-bearing vesicles depositing adhesive anchor points that let the cell pull itself forward. The concept belongs to cell biology and cytoskeletal biophysics, and it illustrates the discipline's principle that directed motion emerges from spatially asymmetric assembly and adhesion rather than from any single motor structure.
Cell motility is the capacity of a cell to generate its own directed movement, distinguished from passive displacement by bulk fluid transport, and it is essential to embryonic tissue formation and t…