In which cellular phase does chromosome condensation occur?

Chromosome condensation occurs during prophase, which is the first stage of mitosis. During this phase, the chromatin, which is a relaxed form of DNA, begins to coil and condense into distinct, visible chromosomes. This condensation is crucial because it allows the chromosomes to be moved and separated accurately during cell division. Each chromosome consists of two sister chromatids, which are joined at a region called the centromere. This visible structure is essential for the proper alignment and segregation of chromosomes in the subsequent phases of mitosis.

In prophase, the nuclear envelope also begins to break down, and the spindle fibers start to form, further preparing the cell for division. This preparation phase is critical for ensuring that each daughter cell receives an identical set of chromosomes. As a result, the condensation of chromosomes in prophase is a key event that facilitates the orderly progression of cell division.