What happens during prophase in mitosis?

During prophase in mitosis, the chromosomes condense and the mitotic spindle begins to form.

Prophase is the first stage of mitosis, the process by which a cell divides its genetic material equally between two new cells. During prophase, the cell's chromatin condenses into a highly ordered structure called chromosomes, which are the genetic blueprints for the new cells. Each chromosome is duplicated and consists of two identical sister chromatids, which are joined at a point called the centromere.

At the same time, the mitotic spindle begins to form. The mitotic spindle is a structure made of microtubules, which are protein strands that extend from one end of the cell to the other. The spindle fibres will eventually attach to the chromosomes and move them to the middle of the cell during the next stage of mitosis, metaphase.

In addition to these changes, the nucleolus, a small structure within the nucleus where ribosome production occurs, disappears. The nuclear envelope, which encloses the nucleus, also begins to break down. This allows the chromosomes to move freely within the cell, ready for the next stages of mitosis.

Prophase is a critical stage in cell division as it prepares the cell for the accurate segregation of chromosomes. It is a complex and highly regulated process, ensuring that each new cell receives an exact copy of the genetic material. This is crucial for maintaining the integrity of the organism's genetic information from one generation of cells to the next.