Final answer:
Microtubules are composed of 13 polymerized dimers of alpha-tubulin and beta-tubulin proteins, forming a hollow cylinder structure. They are the thickest components of the cytoskeleton and are involved in maintaining cell shape, organelle movement, and cell division.
Step-by-step explanation:
Microtubules are small hollow tubes composed of polymerized dimers of alpha-tubulin and beta-tubulin proteins. The walls of the microtubule consist of 13 polymerized dimers, which give it a hollow cylinder structure. These tubules form the thickest components of the cytoskeleton and play essential roles in cell shape, organelle movement, and cell division.