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The molecular structure of DNA is a cornerstone of modern biology, revealing how genetic information is stored and transmitted within living organisms. The double helix, a twisted ladder-like formation, consists of two complementary strands held together by hydrogen bonds between nitrogenous base pairs, a design first elucidated by Watson and Crick. This article provides an in-depth look at the components of the DNA double helix, including the sugar-phosphate backbone, base pairs, and individual nucleotides, using a detailed medical diagram to illustrate these critical elements.