Final answer:
The microtubule assembly in neurons disassembles when tau protein becomes hyper-phosphorylated or when ATP is added to reconstituted microtubule doublets, leading to tau protein tangles and microtubule separation.
Step-by-step explanation:
The microtubule assembly in neurons will fall apart when certain factors disrupt their stability. For example, in neurons, the Microtubule-Associated Protein Tau (MAP-T) binds to and helps stabilize microtubules. However, when tau becomes hyper-phosphorylated, it changes conformation, the microtubules disassemble, and the deformed tau proteins form neurofibrillary tangles. Similarly, the addition of ATP to reconstituted microtubule doublets can lead to microtubules separating as ATP is hydrolyzed. In cell division contexts, microtubules disassemble at the centrioles, contributing to the separation and movement of chromatids during mitosis or meiosis.