Mitosis is a part of the cell cycle in which a single cell divides into two identical daughter cells, each with the same number of chromosomes as the original cell. It’s the process by which organisms grow and replace cells. The process of mitosis is divided into several stages:
- Prophase: The DNA, which was loose within the nucleus, condenses into the form of chromosomes. Each chromosome is made up of two sister chromatids, held together at a region called the centromere. The nuclear envelope begins to break down, and structures called centrioles start moving to opposite ends of the cell. Microtubules extending from these centrioles form the mitotic spindle.
- Metaphase: The chromosomes line up along the metaphase plate, an imaginary line in the middle of the cell. The centromeres of the chromosomes attach to the spindle fibers.
- Anaphase: The sister chromatids of each chromosome are pulled apart by the spindle fibers and move towards opposite poles of the cell.
- Telophase: The chromatids reach the opposite poles of the cell and begin to decondense back into loose DNA. A new nuclear envelope forms around each set of chromosomes.
- Cytokinesis: This is often considered a separate process from mitosis, but it takes place immediately afterwards. The cytoplasm of the cell divides into two, creating two new cells, each with its own nucleus. In animal cells, this occurs through a process called cleavage, while in plant cells, a cell plate forms between the two new nuclei.
These stages ensure that each new daughter cell will have a complete set of chromosomes identical to the parent cell, which is critical for maintaining the genetic stability of an organism. Errors in mitosis can lead to cells with an abnormal number of chromosomes, which can cause various diseases and disorders, including cancer.
