What occurs during prophase in mitosis?

During prophase in mitosis, several crucial events occur that set the stage for proper cell division. First, the chromatin condenses into distinct chromosomes, making them visible under a microscope. Each chromosome, consisting of two sister chromatids, becomes tightly packed and organized for separation.

Additionally, the nuclear envelope, which encases the nucleus, begins to break down and eventually dissolves. This dissolution is vital because it allows the spindle fibers to access chromosomes. As prophase progresses, the spindle apparatus starts to form, which consists of microtubules that extend from the centrosomes. These structures play an essential role in guiding the movement of chromosomes in later phases of mitosis.

In summary, the events during prophase are foundational for the orderly distribution of genetic material to daughter cells, highlighting the importance of chromosome visibility, nuclear envelope breakdown, and spindle formation.