The best description of the structure of a DNA molecule is the "double helix." This iconic shape resembles a twisted ladder, where the "sides" of the ladder are made up of alternating units of deoxyribose (a sugar) and phosphate molecules, and the "rungs" of the ladder are made up of nitrogenous bases. These bases (adenine, thymine, cytosine, and guanine) pair up with each other through hydrogen bonds, forming the base pairs that code for genetic information. The double helix structure allows DNA to store, transmit, and replicate genetic information in a compact and efficient manner.