Cell Division - Mitosis.
In order to survive and grow our cells and DNA have to be able to divide.
Mitosis Makes New Cells for Growth and Repair.
Body cells normally have two copies of each chromosome - one from the organisms mother and the one from it's father. So humans have two copies of chromosome 1 and chromosome 2, etc.
This diagram shows 23 pairs of chromosomes from a human cell. The 23rd one is a bit different but that's for another section.
When a body cell divides it needs to make new cells identical to the original cell - with the same number of chromosomes.
This type of cell division is called mitosis. It's used when plants and animals want to grow or to replace cells that have been damaged.