Deoxyribonucleic acid (DNA) is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (nuclear DNA), but a small amount can also be found in the mitochondria (mitochondrial DNA). The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
