During which phase of mitosis do the chromatin form visible chromosomes?

During prophase, the chromatin, which is in a loosely packed and less visible form during interphase, begins to condense into distinct structures known as chromosomes. This is a critical step in mitosis, as the condensation of chromatin allows the chromosomes to become more compact and manageable as they prepare for the eventual separation into daughter cells.

In this phase, the nuclear envelope begins to break down, and the mitotic spindle starts to form. The chromosomes appear as two sister chromatids joined at the centromere, making them very visible under a microscope. Understanding this process is essential, as the proper formation and alignment of chromosomes during mitosis are crucial for accurate cell division and genetic stability in the resulting daughter cells.

In contrast, during metaphase, the chromosomes are already visible and align along the metaphase plate but do not form new visible chromosomes. Telophase is characterized by the reformation of the nuclear envelope around separated chromosomes, which are de-condensing back into chromatin. Interphase is the preparatory phase before mitosis, where DNA is replicated, but chromosomes are not yet visible.