What best describes the structure of DNA?

The structure of DNA is best described as a double helix with a phosphate-sugar backbone. This means that DNA consists of two long strands that twist around each other resembling a spiral staircase. Each strand is made up of a sequence of nucleotides, which include a phosphate group, a deoxyribose sugar, and one of four nitrogenous bases (adenine, thymine, cytosine, or guanine). The unique pairing of these bases (adenine with thymine and cytosine with guanine) creates the rungs of the helical ladder, while the phosphate and sugar molecules form the sides of the ladder.

The double helix structure is critical for DNA’s function in storing genetic information, as it allows for precise replication during cell division and the encoding of instructions for building proteins. This organized yet flexible structure is vital for the stability of genetic information and the processes of transcription and translation within cells.