What is the first phase of mitosis called?

The first phase of mitosis is called prophase. During prophase, several key events occur that set the stage for the subsequent steps in cell division. The chromatin, which is the relaxed form of DNA found in the nucleus during interphase, condenses into visible chromosomes. Each chromosome is made up of two sister chromatids joined at a region known as the centromere.

Additionally, during prophase, the nuclear envelope begins to break down, and the mitotic spindle forms, which is an essential structure for separating chromosomes. The spindle fibers emerge from the centrosomes as they move toward opposite poles of the cell. Together, these changes prepare the cell for the alignment of chromosomes that will occur in the next phase, metaphase. Understanding prophase is crucial, as it marks the transformation from a non-dividing state to the active process of mitosis where the genetic material is organized and prepared for distribution into daughter cells.