Final answer:
Actin filaments, microtubules, and virus capsids are all constructed from assemblages of identical proteins that are essential for cell structure and function.
Step-by-step explanation:
Actin filaments, microtubules, and the spherical shells of certain virus particles are all structures built from assemblages of identical proteins. Microtubules are made up of α- and β-tubulin protein monomers, and microfilaments are composed of actin protein monomers. Considering virus particles, they are typically composed of repeating protein subunits that form a capsid, contributing to their spherical shape. These proteins allow for the various functions within the cell, such as determining cell shape and enabling motility.