What is the structural composition of DNA?

The structural composition of DNA is best described as two long chains of nucleotides that are twisted together to form a double helix. DNA, or deoxyribonucleic acid, consists of two strands that run in opposite directions (antiparallel) and are interconnected by base pairs formed between nitrogenous bases (adenine pairs with thymine, and cytosine pairs with guanine). This specific arrangement not only provides a stable structure but also enables the efficient storage and transmission of genetic information.

The double helical structure of DNA, first described by James Watson and Francis Crick in 1953, is crucial for its function in heredity and replication. This helical formation allows DNA to maintain its length while being packaged tightly within the nucleus of cells. Additionally, the specific pairing of bases facilitates accurate copying during cell division, ensuring that genetic information is reliably passed on.

In contrast, the other options present incorrect or unrelated concepts regarding DNA structure.