DNA is a large molecule that contains two intertwined, complementary strands of deoxyribonucleotides that form a double helix shape. Also included is a backbone of a 5-carbon sugar (deoxyribose) and phosphate groups. Within DNA are four different chemical bases. The four bases are: adenine (A), guanine (G), thymine (T), and cytosine (C). Certain bases can bond with each other, and these complementary bases can form hydrogen bonds. Adenine bonds only with thymine, while guanine bonds with cytosine. The configuration of these nitrogenous bases is key as it determines the characteristics that are created by DNA (DiscoveryEducation).