What describes the structure of DNA?

The structure of DNA is best described as a double helix composed of nucleotides. This unique configuration consists of two long strands of nucleotides that twist around each other, resembling a ladder or spiral staircase. Each nucleotide is made up of three components: a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine).

The specific pairing of the nitrogenous bases – adenine with thymine and cytosine with guanine – forms the rungs of the helix, while the sugar-phosphate backbone constitutes the sides of the ladder. This structure is critical for DNA's function in storing and transmitting genetic information, as it allows for the precise replication and encoding of genetic material during cell division.

The other choices do not accurately represent the structure of DNA. For instance, stating that DNA is a single strand of nucleotides ignores the essential double-stranded nature of its molecular architecture. The idea of a linear arrangement of amino acids reflects protein structures rather than nucleic acids. Lastly, describing DNA as two parallel strands of sugars misrepresents its true composition, which involves nucleotides with phosphate and nitrogenous bases as well,