Final answer:
The nucleation of microtubules is more difficult than the nucleation of actin filaments due to their structural and functional differences. This difficulty is reflected in the organization of the microtubule network, which plays a crucial role in cell division and the movement of genetic material.
Step-by-step explanation:
Microtubules are larger and more complex structures, made up of tubulin protein subunits that assemble into hollow cylinders. Actin filaments, on the other hand, are thinner and composed of actin protein chains twisted together. This structural complexity makes it more challenging for microtubules to nucleate and form.
This difficulty in nucleation is reflected in the organization of the microtubule network. Microtubules tend to radiate from centrioles in non-dividing animal cells, without forming discrete structures. However, during cell division, microtubules reorganize and form spindle fibers. This reorganization is nucleated from centrioles in animal cells. The complex organization and arrangement of microtubules play a crucial role in cell division and the movement of genetic material during mitosis or meiosis.