Final answer:
The structure of DNA was determined by Watson and Crick in 1953, building on Chargaff's rule and X-ray crystallography data.
Step-by-step explanation:
The general structure of nucleic acids, specifically DNA, was discovered in 1953 by James Watson and Francis Crick. They concluded that DNA has a double helix structure. This discovery was supported by the previous work of Erwin Chargaff and the X-ray crystallography photographs taken by Rosalind Franklin and Maurice Wilkins. Chargaff's rule noted that adenine (A) always pairs with thymine (T) and guanine (G) with cytosine (C), which was critical in deducing the DNA structure. The discovery of the nucleic acid structure was a monumental step in understanding the molecular basis of heredity and genetic coding.