Final answer:
Microtubules are polar structures composed of polymerized dimers of a-tubulin and ß-tubulin proteins. They have a distinct plus and minus end. The structure of a microtubule consists of 13 polymerized dimers of a-tubulin and ß-tubulin proteins.
Step-by-step explanation:
Microtubules are small hollow tubes made up of polymerized dimers of a-tubulin and ß-tubulin proteins. They have a diameter of about 25 nm and are the widest components of the cytoskeleton. Microtubules are polar, meaning they have distinct plus (+) and minus (-) ends. The plus end grows by adding more tubulin subunits, while the minus end disassembles.
The structure of a microtubule consists of 13 polymerized dimers of a-tubulin and ß-tubulin proteins. These proteins form the walls of the hollow tube. The microtubules serve various functions in the cell, such as providing structural support, acting as tracks for transport within the cell, and aiding in the movement of chromosomes during cell division.