Final answer:
Cells without centrosomes rely on alternative mechanisms like MTOCs for mitotic spindle assembly or utilize the nuclear envelope and motor proteins to organize microtubules, ensuring proper chromosome separation during cell division.
Step-by-step explanation:
Cells without centrosomes can still assemble a functional bipolar mitotic spindle because they have an alternative mechanism for spindle assembly. While animal cells rely on the presence of centrosomes for mitotic spindle formation, plant cells and certain other eukaryotic cells use structures known as Microtubule Organizing Centers (MTOCs) to perform a similar function. In the absence of centrioles, these MTOCs facilitate the nucleation of microtubules and provide the structural framework necessary for the assembly of the mitotic spindle, ensuring the proper separation of chromosomes during cell division.
The specific mechanisms may vary among different organisms and cell types. For instance, in cells where the nuclear envelope remains intact throughout mitosis, such as yeast, the spindle formation occurs within the confines of the nucleus, with the nuclear envelope playing a supporting role. In others, like certain animal cells lacking centrosomes, microtubules can self-organize via the action of motor proteins and the chromosomes themselves, which can serve as platforms for microtubule nucleation.