Final answer:
The +end (plus end) of microtubules is oriented away from the centrosome, where the tubulin dimers add to the growing microtubule, whereas the -end (minus end) is typically anchored at the centrosome or MTOC.
Step-by-step explanation:
When microtubules grow out of a centrosome, the end oriented away from the centrosome is known as the +end (plus end). Microtubules are composed of a-α-tubulin and β-tubulin dimers that assemble into filamentous structures with inherent polarity; they grow by adding these dimers to the +end, which is fueled by GTP hydrolysis. Conversely, the opposite end of the microtubule, known as the -end (minus end), is typically anchored at the centrosome or microtubule-organizing center (MTOC) and may disassemble during the cell cycle or other cellular processes. This arrangement is critical for various cellular activities, including the proper separation and movement of chromatids during mitosis or meiosis, as well as the formation of the mitotic spindle that separates chromosomes during cell division.