Lesson 5: Meiosis
To grow tissue and renew cells, existing cells divide by mitosis. The steps of mitosis are:
- 1.Growth in cell size
- DNA replication. The chromosomes duplicate themselves so that instead of two copies of every gene per cell (the normal diploid condition), there are 4 copies of every gene.
- The cell's nucleus dissolves, and the chromosomes distribute themselves into two identical diploid sets at opposite sides of the cell.
- Two new nuclei form around the sets of chromosomes.
- The cell splits into two cells, each with its own nucleus and each with a diploid set of chromosomes.
Mitosis produces genetically identical cells. Cells in the human body divide by mitosis. The only exception occurs during the production of sperm and egg cells. These cells are produced by meiosis.
