What is the structure of DNA?

The correct answer emphasizes the iconic double-helix structure of DNA, which was first described by James Watson and Francis Crick. DNA consists of two long strands that are intertwined, resembling a twisted ladder. These strands are composed of alternating sugar and phosphate groups, giving DNA its backbone.

The nitrogen bases—adenine, thymine, cytosine, and guanine—are the rungs of the ladder. They are paired specifically (adenine with thymine, and cytosine with guanine) through hydrogen bonding, which facilitates the replication and transmission of genetic information. This specific pairing is essential for the accurate copying of DNA during cell division and serves as the foundation for heredity.

This structure is crucial because it allows DNA to store vast amounts of genetic information in a stable form, enabling the transmission of traits from parents to offspring. Additionally, the double-helix configuration provides the necessary stability while allowing the strands to separate during processes such as replication and transcription. Therefore, the description of DNA as a double helix with sugar, phosphate, and nitrogen bases captures the essential features that define its structure and function in living organisms.