DNA Structure (1953)

Watson and Crick's determination of DNA's double helix structure in April 1953 — using Rosalind Franklin's X-ray crystallography data without her full knowledge — is the most consequential biological discovery of the 20th century. Understanding DNA's structure explained how genetic information is stored and transmitted, launched the fields of molecular biology and genetic engineering, and made possible the biotech industry, genome sequencing, mRNA vaccines, and CRISPR gene editing.