DNA Day is celebrated April 25.

On this date in 1953, James Watson's and Francis Crick's paper describing the structure of DNA was published in the journal Nature. With help from other scientists, Watson and Crick were the first to describe DNA as a double helix, or a twisted ladder shape. Notably, their model of DNA suggested how genetic information is stored and copied. DNA Day also marks the completion of the Human Genome Project, the 13-year international effort that identified the order, or sequence, of more than 3 billion building blocks (bases) in human DNA. The Human Genome Project was finished in 2003, 50 years after Watson and Crick described DNA as a double helix.

Please use the links below to learn more about DNA Day, the discovery of DNA's structure, and the Human Genome Project.

• The 1953 paper by Watson and Crick (Nature)
• Principal scientists behind the structure of DNA (The Chemical Heritage Foundation)
• The Francis Crick Papers (U.S. National Library of Medicine)
• James D. Watson Archives (Cold Spring Harbor Laboratory Archives)
• DNA activities and teaching tools (National Human Genome Research Institute)
• National DNA Day High School Essay Contest (American Society of Human Genetics)
• Build a DNA Molecule (Genetic Science Learning Center, University of Utah)
• The Human Genome Project and Genomic Research