Final answer:
The plus end of a microtubule is terminated by a row of α-tubulin and β-tubulin dimers. These structures grow by adding tubulin subunits and play a critical role in cell division by forming the mitotic spindle that separates chromosomes.
Step-by-step explanation:
The plus end of a microtubule is terminated by a row of α-tubulin and β-tubulin dimers. Microtubules are essential components of the cell's cytoskeleton and provide structural support and a means of transportation within the cell. They are made of polymerized dimers of α-tubulin and β-tubulin, which comprise the hollow walls of the microtubule. Microtubules grow by adding tubulin subunits to their plus end and can rapidly disassemble and reassemble.
During cell division, particularly in mitosis and meiosis, microtubules form the mitotic spindle, which is crucial for the separation of chromosomes into daughter cells. This complex process involves the dynamic assembly and disassembly of microtubules at their plus and minus ends. The disassembly at the minus ends, which are usually anchored at microtubule-organizing centers such as centrosomes, helps in pulling the chromatids or daughter chromosomes apart.