The Structure of DNA: A Double Helix: A DNA double helix structure, showcasing its intricate and complex nature. The strand is composed of two complementary strands twisted together in a spiral fashion, with the sugar-phosphate backbone on the outside and nitrogenous bases projecting inward from the backbone and pairing up with their counterparts on the opposing strand to form rungs. The image highlights the unique structure of DNA, which allows for its replication and transmission of genetic information from one generation to the next.