Deoxyribonucleic acid (DNA) is the primary source of genetic information in cells. Humans, plants, animals, and bacteria all contain DNA. DNA is physically passed from generation to generation to bestow certain traits of parents to their children. The reason why children have physical characteristics from each of their parents — a child may have their mother's eye color and father's hair color — is that they received half their DNA from each parent.

Each of our cells (with a few exceptions like red blood cells, eggs and sperm) contains all the DNA required to code for our genetic features. Individual regions of DNA that confer traits are called genes. Information in genes is relayed to the protein synthesis machinery within cells where it dictates the production of proteins. The DNA in each of our cells is present as 46 individual lengths of DNA called chromosomes. Chromosomes