Mitosis: Early Phases
Before a cell divides, it goes through Interphase, which has three important stages. During G₁ Phase, the cell grows larger. In S Phase, the cell makes an exact copy of all its DNA. Finally, in G₂ Phase, the cell checks for mistakes before committing to division.
When mitosis officially begins, Prophase kicks things into high gear. Chromosomes condense from their loose, spaghetti-like form into compact, organized structures. This happens when DNA wraps tightly around proteins called histones. The nuclear envelope (the membrane around the cell's nucleus) breaks down, while centrioles move to opposite ends of the cell and form spindle fibers.
In Metaphase, all chromosomes line up precisely along the middle of the cell at what's called the metaphase plate. Think of this as the cell's equator. Spindle fibers fully attach to each sister chromatid (the duplicated chromosome copies), preparing them for separation.
Fun Fact: If you could stretch out all the DNA from just one of your cells, it would be about 6 feet long! Condensing it into chromosomes during prophase is like neatly packing a 6-foot string into a tiny space smaller than a dust particle.
