Intermediate filaments are the most skeletal in nature, giving the cytoplasm mechanical strength.
Actin filaments and microtubules are dynamic, turning over many times during their functional lifetimes. These polymers also are polar, in the sense of having different biochemical properties at each end. Their dynamic behavior and polarity are enhanced by free energy from the hydrolysis of nucleoside triphosphates. The biochemical properties of cytoskeletal polymers themselves appear to be widely conserved among eukaryotes. The different functions of the cytoskeleton are mediated by various accessory proteins, which assemble, disassemble, bundle, sever, cap, cross-link, or move the polymers.