What occurs during the prophase stage of mitosis?

During the prophase stage of mitosis, chromosomes condense and become visible under a microscope. This is a crucial step in the process of cell division, as it allows for the individual chromosomes, each comprised of two sister chromatids, to be clearly distinguished. As the chromatin fibers, which are loosely organized DNA and protein, coil and fold more tightly, they form the characteristic structures we observe as chromosomes.

Furthermore, prophase marks the beginning of the mitotic phase, setting the stage for subsequent steps such as the breakdown of the nuclear envelope and the alignment of chromosomes. The visibility of chromosomes at this stage is essential for ensuring that they can be accurately separated during later phases of mitosis, which is vital for achieving proper genetic distribution to daughter cells.