What occurs during prophase in cell division?

During prophase in cell division, the nuclear envelope begins to disappear, marking a significant phase in the process of mitosis or meiosis. This step is crucial because it allows the spindle fibers to access the chromosomes, which are becoming increasingly condensed and visible.

As prophase progresses, the chromatin fibers—loose DNA strands—condense into distinct chromosomes, each consisting of two sister chromatids joined at a region called the centromere. The breakdown of the nuclear envelope signifies the transition from the interphase preparation stage to the active chromosome manipulation stage of mitosis or meiosis, facilitating the separation and movement of chromosomes to opposite poles of the cell in subsequent phases.

The other processes listed, such as aligning chromosomes along the metaphase plate, the separation of chromatids, and the formation of daughter cells, occur in later stages of cell division. Therefore, the disappearance of the nuclear envelope is a defining feature of prophase.