Final answer:
Microtubules are small hollow tubes made of α-tubulin and ß-tubulin proteins. They provide tracks for chromosome movement during cell division and resistance to compression. They have polarity, with a growing plus end and a disassembling minus end.
Step-by-step explanation:
Microtubules are small hollow tubes made of polymerized dimers of α-tubulin and ß-tubulin proteins. They have a diameter of about 25 nm and are the widest components of the cytoskeleton. Microtubules play a crucial role in cell division, acting as tracks along which replicated chromosomes are pulled to opposite ends of the cell. They also help the cell resist compression and provide a pathway for vesicles to move within the cell
Microtubules have polarity, meaning they have distinct plus and minus ends. The plus end is the growing end, where α/ß-tubulin dimers add to the microtubule, fueled by GTP hydrolysis. The minus end is the disassembling end, where microtubules disassemble. The polarity of microtubules is important for their function in cell division, as well as for the sliding of microtubules in processes like the separation of chromatids during mitosis.
The polarity of microtubules has been demonstrated in experiments where microtubules were shown to grow by addition at one end and disassemble at the opposite end. In addition, motor proteins like dynein are involved in sliding microtubules past one another in processes like cell division. The polarity of microtubules is essential for the proper organization and functioning of cells.