Final answer:
The αβ-tubulin heterodimer constructs the hollow tube structure of microtubules with distinct plus and minus ends, which are important for various cellular functions including vesicle transport and chromosome segregation.
Step-by-step explanation:
The αβ-tubulin heterodimer is a foundational structural unit with an plus end at one end and a minus end at the other end that have the same polarity. Microtubules are composed of 13 polymerized dimers of α-tubulin and β-tubulin, forming a hollow tube structure which is essential for various cellular functions. The plus end typically represents the growing end where tubulin dimers add on, while the minus end is more stable and less dynamic. This polarity is important for the directional movement of vesicles and organelles inside the cell, and for the proper segregation of chromosomes during cell division.