Final answer:
Intermediate filaments are composed of tetramers that associate linearly to form variable-length filaments, providing mechanical support and elasticity to cells, adapting to changes in cell shape through dynamic assembly.
Step-by-step explanation:
Eight tetramers associate with one another in a linear arrangement to form a filament that is variable in length. This association occurs in intermediate filaments, which are made of proteins that exhibit a common structure. These structures have monomers with globular domains separated by coiled rod regions, which give the filaments their elasticity and stretchability.
Unlike microtubules and actin filaments, intermediate filaments do not have 'plus' and 'minus' ends and can stretch, providing mechanical support to cells. Intermediate filaments can also disassemble and reassemble as needed, allowing cells to change shape without losing integrity.