Our cells reproduce so that we can grow and regenerate. For example, cells are constantly doubling so that our nails and hair continue to grow. The process by which a cell divides into two genetically identical copies is called mitosis. To accomplish this, the cell must first make a second copy of all the DNA in its nucleus. The DNA then condenses into rod-like structures known as chromosomes.
Both copies of the chromosomes are glued together in the middle, so they look like an X under the microscope. Once the nuclear membrane is ruptured, the chromosomes line up in an orderly row in the center of the cell. The chromosome pairs then divide and move to opposite poles of the cell before it divides into two genetically identical daughter cells. When the sex cells, the sperm and the egg, are involved, cell division takes place to a completely different level! The process is called meiosis.
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