Cytoskeleton Structure



protein found in all eukaryotic cells. Its monomeric form is the subunit of actin filaments.

actin filament

polymer made of actin monomer subunits with a diameter of about 7 nm. Actin filaments play a major role in muscle contraction, cell movement, and cell shape.

cell cortex

network of actin filaments beneath the plasma membrane


one of a perpendicular pair of barrel-shaped structures in the centrosome, composed of nine triplets of microtubules arranged in a cylinder


structure in the cytoplasm of animal cells that coordinates the formation of microtubules, which allows cell division to proceed during reproduction

cilium (plural, cilia)

small, hairlike projection from cells that can be used for motility or to filter air in the respiratory system


network of filaments that gives the cell its shape and forms the support network for cell functions, such as cell division


motor protein that moves from the plus end to the minus end of microtubules

flagellum (plural, flagella)

threadlike tail that allows some cells to move. Structure differs between prokaryotes and eukaryotes.

intermediate filament

ropelike cytoskeletal filament 8–12 nm in diameter that functions primarily as a structural protein in eukaryotic cells


two-headed ATPase motor protein that moves materials from the minus end of microtubules toward the plus end


long tubulin filament that plays a role in cell structure, organization, mitosis, and movement

microtubule organizing center (MTOC)

general term for a place in the cell from which microtubules grow

motor protein

protein, such as dynein or kinesin, that uses the energy released by the hydrolysis of ATP to move along a cytoskeletal filament


group of protein monomers that polymerize into protofilaments, which in turn form microtubules