- New cells for growth and repair.
- Human body cells are diploid (2 versions of each chromosome).
- When a cell divides, it makes 2 copies of the original cell : nucleus contains same number of chromosomes as original. (mitosis)
- In a cell that isn't dividing, DNA is spread out in long strings inside the cell.
- If the cell is told to divide, it has to duplicate it's DNA (One copy for each new cell).
- The DNA is copied and forms X shaped chromosomes. Each arm is identical (left arm has same DNA as right).
- The chromosomes line up in the centre of the cell and cell fibres pull them apart.
- The two arms of each chromosome go to opposite ends of the cell.
- Membranes form around each set of chromosomes.
- They become the nuclei of the 2 cells.
- Lastly the cytoplasm divides.
- There are now 2 new identical cells.