Rosalind Franklin was a British chemist and X-ray crystallographer whose work was central to discovering the double-helix structure of DNA. She is best known for “Photograph 51,” an X-ray diffraction image of DNA that provided critical evidence for the structure proposed by James Watson and Francis Crick in 1953. But DNA was only part of her story. Franklin made foundational contributions to understanding coal, carbon, and virus structures in a career cut short by her death at age 37.
Photograph 51 and the Structure of DNA
Franklin arrived at King’s College London in 1951, where she was tasked with using X-ray crystallography to study DNA fibers. This technique works by firing X-rays at a substance and capturing the pattern they make as they bounce off atoms, revealing the arrangement of molecules inside. Franklin refined the method with extraordinary precision, exposing high-quality DNA samples to carefully controlled humidity levels. She discovered that in wet conditions, the DNA strands stretched and produced a distinctive X-shaped pattern, while dry strands thickened and scattered X-rays into many distinct spots. These two forms of DNA had never been clearly separated before.
From these images, Franklin calculated that DNA had ten stacked bases per turn of its helix. She deduced that the phosphate groups (the backbone of the molecule) sat on the outside, with the bases tucked on the inside. She even worked out that the two chains of the double helix were offset from each other by three-eighths of a full turn, a detail she inferred from a missing spot in the diffraction pattern. By early 1953, she had drafted a manuscript proposing that DNA most likely formed a double helix.
That manuscript never made the splash it should have. Watson and Crick, working at Cambridge, gained access to Franklin’s unpublished data without her knowledge. Some of it reached them through internal documents not meant for outside distribution; some came from her colleague Maurice Wilkins, who shared her findings during conversations with Watson. Armed with this information, Watson and Crick built their famous model and published it in April 1953. Franklin’s own paper appeared in the same issue of Nature, presented as supporting evidence rather than the foundation it actually was.
Why She Was Left Out of the Nobel Prize
In 1962, Watson, Crick, and Wilkins received the Nobel Prize in Physiology or Medicine for determining the structure of DNA. Franklin was not included. The most straightforward reason is that she had died of ovarian cancer on April 16, 1958, at age 37, and the Nobel Prize is not awarded posthumously. But the deeper issue is how her contributions were minimized even while she was alive. Watson’s own memoir, published years later, described her dismissively, and for decades her role was either downplayed or omitted from popular accounts of the discovery.
As early as November 1951, Franklin had given a seminar (which Watson attended) where she concluded that DNA formed “a big helix in several chains, phosphates on the outside.” When Watson and Crick then built a triple-helix model with the backbone on the inside, Franklin immediately pointed out that it contradicted the X-ray data. She was right. It took them another year, and access to her more refined measurements, to get the structure correct.
Her Earlier Work on Coal and Carbon
Before DNA, Franklin spent several years studying the molecular structure of coal and carbon, first at the British Coal Utilisation Research Association during World War II and then at a government laboratory in Paris. This work was far from obscure. She established a classification system for carbon materials that is still used today, dividing coals and other solid organic materials (including certain plastics) into two categories: those that convert readily into graphite when heated, and those that yield “non-graphitizing” carbons, which are low-density, highly porous, and extremely hard. This distinction proved important for industrial applications ranging from fuel technology to materials science.
Pioneering Research on Viruses
After leaving King’s College in 1953, Franklin moved to Birkbeck College in London and turned her crystallographic skills to viruses. She spent the next five years producing some of the most detailed structural studies of viruses ever completed at that time.
Her primary focus was the tobacco mosaic virus, a rod-shaped virus that infects plants. Franklin confirmed that the virus’s protein coat forms a spiral hollow tube, with the genetic material (RNA, not DNA) wrapped around the protein rather than running through the center. She also demonstrated that the viral RNA was a single strand, unlike the double helix of DNA. These findings were significant for understanding how viruses assemble themselves and how their genetic material is packaged.
In 1956, a visit to the University of California, Berkeley, inspired her to take on polio virus research. The work was funded by the U.S. National Institutes of Health, though conducted in London. Franklin handled live strands of the virus in her lab, much to the alarm of her colleagues. Her research team ultimately determined that the polio virus has icosahedral symmetry, meaning its protein shell has 60 faces arranged like a soccer ball. Franklin continued this work through 1957 even as she was being treated for cancer, but she did not live to see the results published.
Her Legacy Beyond the Lab
Recognition of Franklin’s contributions has grown steadily since her death. The European Space Agency named its ExoMars rover “Rosalind Franklin,” a mission designed to search for signs of past life on Mars. Universities, research buildings, and scientific prizes around the world bear her name. Perhaps most importantly, her story reshaped how the scientific community talks about credit and collaboration, serving as one of the most prominent examples of a woman scientist whose work was used by others without proper acknowledgment. The data she gathered, the techniques she refined, and the structures she solved would have been landmark achievements for any scientist. That she accomplished all of it in roughly 15 working years makes the record even more striking.