Nucleic acid double helix
![Two complementary regions of nucleic acid molecules will bind and form a double helical structure held together by base pairs.](/Images/godic/202501/09/DNA_orbit_animated_static_thumb0911.png")
![Base pair geometries](/Images/godic/202501/09/CCF10292011_000000911.jpg")
![The structures of A-, B-, and Z-DNA.](/Images/godic/202501/09/Dnaconformations0911.png")
![The helix axis of A-, B-, and Z-DNA.](/Images/godic/202501/09/B&Z&A_DNA_formula0911.jpg")
In molecular biology, the term double helix refers to the structure formed by double-stranded molecules of nucleic acids such as DNA. The double helical structure of a nucleic acid complex arises as a consequence of its secondary structure, and is a fundamental component in determining its tertiary structure. The term entered popular culture with the publication in 1968 of The Double Helix: A Personal Account of the Discovery of the Structure of DNA, by James Watson.