Question

Why are both ends of a microtubule different structurally?

Answer 1

Microtubule:

1. The cytoskeleton of the cell is made up of tiny, alpha- and beta-tubulin-based hollow tubes called microtubules.
2. The two ends of a microtubule differ structurally because all the tubulin dimers in a filament are positioned in the same way.
3. One of the ends is an exposed b-tubulin plus end, while the other ends are an a-tubulin minus end.
4. Due to variations in the rate at which tubulin subunits connect or disassociate, microtubules have variable growth and shrinkage characteristics at their two ends.
5. The rate of tubulin attachment at the plus end is larger than that at the minus end, which is the most significant difference.
6. Therefore, in the presence of an abundance of free tubulin subunits, the plus end expands faster than the minus end.