Rosalind Franklin: X-ray Crystallography and the Structure of DNA

Rosalind Elsie Franklin was born on July 25, 1920, in London, England. Her early education took place at St Paul's Girls' School in London, where she received a rigorous foundation in the sciences. She subsequently attended Newnham College, Cambridge, where she studied chemistry and graduated in 1941. Her undergraduate years coincided with the onset of World War II, a period that would shape the early direction of her scientific career.¹

After completing her undergraduate studies, Franklin worked at the British Coal Utilisation Research Association during World War II. This position allowed her to apply physical chemistry to a pressing national need: understanding the structure and behavior of coal. Her work on coal helped classify coals and understand their structure, a contribution that would later underpin her doctoral research. In 1945, she received her Ph.D. from Cambridge, with her coal work serving as the foundation for that degree.¹

In 1947, Franklin moved to Paris, where she worked at the Laboratoire Central des Services Chimiques de l'Etat until 1950. During this period, she learned X-ray diffraction techniques, a set of methods that would become central to her subsequent scientific achievements. Her time in Paris marked a decisive turn toward structural biology and the study of molecular architecture using physical methods. This training in X-ray diffraction positioned her for the groundbreaking work that lay ahead.²

In 1951, Rosalind Franklin joined King's College London as a research associate. She worked at King's College London from 1951 to 1953, situated within the Medical Research Council Biophysics Unit. At King's, she was assigned to work on DNA using X-ray diffraction, a project that would define her scientific legacy. Her colleague at King's was Maurice Wilkins, with whom she would share a fraught and difficult working relationship.³

At King's, Franklin used X-ray diffraction to study the structure of DNA, applying the techniques she had mastered in Paris. She discovered that DNA had two forms, A and B, a critical finding that clarified much of the confusion surrounding earlier diffraction studies. The B form was the hydrated form and gave clearer diffraction patterns, making it especially informative for structural analysis. Photo 51, the image that would become legendary, was of the B form of DNA.¹

Franklin's X-ray diffraction images are among the most famous in science, and her data indicated that DNA had a repeating structure. She measured the distances between repeating units in DNA, and her measurements were consistent with the double helix model that Watson and Crick would later propose. Her data indicated that the phosphate groups were on the outside of the DNA molecule, a key structural constraint. She determined that the DNA molecule was a helix with two strands.⁴

The working atmosphere at King's was not collaborative. Franklin and Wilkins had a difficult working relationship, a friction that has been extensively documented in historical accounts. Despite this, her time at King's produced some of the most consequential experimental data in the history of molecular biology. She left King's in 1953, but the data she generated there would continue to shape the field for decades. Her colleague Maurice Wilkins shared her data with Watson and Crick.¹

Photo 51 is an X-ray diffraction image of DNA taken by Raymond Gosling in May 1952, working as a PhD student under the supervision of Rosalind Franklin. The image was taken using X-ray crystallography and showed a distinctive X-shaped pattern. The X-shaped pattern indicated a helical structure, a conclusion that was central to the emerging understanding of DNA. The image was critical evidence for the helical structure of DNA.⁵

Franklin's data, including Photo 51, was shown to Watson and Crick without her knowledge or permission. Franklin's X-ray image Photo 51 was shown to Watson by Wilkins, an act of data sharing that has been the subject of extensive historical scrutiny. Watson immediately recognized the helical structure from the image, a moment that accelerated the race to solve DNA's structure. Franklin's data provided the crucial evidence for the double helix model.⁶

Franklin's X-ray diffraction images provided key information about the helical structure of DNA, and she independently deduced key features of DNA structure. Her data indicated that DNA had a repeating structure and that phosphate groups were on the outside of the molecule. These deductions were made independently, yet they converged with the model being built at Cambridge. Her work was essential to the discovery of the structure of DNA.⁷

Watson and Crick published their double helix model in Nature in 1953, the same year Franklin's DNA work appeared in a series of Nature papers. Franklin's paper in Nature provided evidence for the helical structure of DNA, and her paper appeared in the same issue as Watson and Crick's. Her paper provided experimental support for the double helix, complementing the model-building approach of the Cambridge group. Franklin's work on DNA was published in 1953, cementing her place in the historical record.⁸

Franklin's contributions to the discovery of the double helix were largely overlooked during her lifetime. She was not informed that her data was being used by Watson and Crick, and she was not aware that her data had been shared. Franklin's data was used by Watson and Crick without her consent, a fact that has fueled decades of debate about scientific ethics and credit. Her contribution to the discovery of the double helix was significant, yet recognition came slowly.⁶

The Nobel Prize in Physiology or Medicine 1962 was awarded to Francis Crick, James Watson and Maurice Wilkins. Rosalind Franklin was not awarded a Nobel Prize, and the Nobel Prize is not awarded posthumously, meaning that her death in 1958 rendered her ineligible. Franklin died of ovarian cancer at the age of 37, only four years before the prize was awarded. Her contribution was recognized posthumously, but not with the Nobel honor that went to her contemporaries.⁹

In the decades following her death, historians and scientists have reassessed Franklin's role. Franklin's contribution to the discovery of the double helix is now widely recognized, and she is often called the 'wronged heroine' of DNA. Her work on DNA was essential for the discovery of the double helix, a judgment that has become mainstream in histories of molecular biology. Franklin's data was crucial for Watson and Crick's model of DNA.¹⁰

The recognition of Franklin's contributions has also brought attention to the structural nature of scientific collaboration and competition. Franklin's work was not fully acknowledged until after her death, a delay that has been attributed to a combination of institutional dynamics, gender bias, and the informal sharing of data. She played a critical role in the discovery of the DNA double helix, a role that is now taught in textbooks and celebrated in biographies. Her legacy is honored by numerous institutions and awards.¹

After leaving King's, Franklin worked at Birkbeck College, London, from 1953 until her death in 1958. At Birkbeck, she studied the structure of viruses, including tobacco mosaic virus, shifting her focus from DNA to the broader field of structural virology. Her work on the tobacco mosaic virus revealed its helical structure, and she showed that the virus's protein coat was helical. This work laid the foundation for structural virology.²

Franklin collaborated with Aaron Klug on virus structure, a partnership that would prove scientifically fruitful. Aaron Klug later won a Nobel Prize in Chemistry in 1982, a testament to the quality of the research environment Franklin fostered and contributed to. Franklin's work on viruses contributed to the understanding of their structure, and her virus work laid the foundation for structural virology. Her transition from DNA to viruses demonstrated her versatility as a structural biologist.¹

Franklin's early work on coal had already established her as a meticulous and innovative scientist. Her work on coal helped classify coals and understand their structure, and she published a paper on the structure of coal in 1950. She was a pioneer in the use of X-ray crystallography to study biological molecules, a methodological approach that she applied across coal, DNA, and viruses. Her career arc reflects a consistent commitment to applying physical techniques to biological problems.¹

Rosalind Franklin died on April 16, 1958, in London, at the age of 37. She died of ovarian cancer at the age of 37, a disease that cut short a career that was still in its most productive phase. Her death came only four years before the Nobel Prize in Physiology or Medicine was awarded to Crick, Watson, and Wilkins. The timing of her death has been a point of poignant reflection in the history of science.¹

Franklin's final years at Birkbeck were marked by intense scientific productivity despite her declining health. She continued to work on virus structure, collaborating with Aaron Klug and others, and her contributions to the understanding of tobacco mosaic virus were substantial. Her death in 1958 removed from the scientific community one of its most skilled crystallographers. The full significance of her DNA work would only become widely appreciated in subsequent decades.¹

Franklin's legacy is honored by numerous institutions and awards, reflecting a growing recognition of her scientific contributions. The Royal Society established the Rosalind Franklin Award in 2003, and the award supports women in science, technology, engineering, and mathematics. The Royal Society's Rosalind Franklin Award was first given in 2003, marking a formal institutional commitment to recognizing her and supporting others in her field. King's College London named the Rosalind Franklin Building in her honor.³

The Rosalind Franklin University of Medicine and Science in North Chicago, Illinois, is named after her, extending her legacy into medical education in the United States. The Rosalind Franklin Award is given annually by the Royal Society, and it continues to support women in STEM fields. These honors represent a broad institutional acknowledgment of her scientific importance. Her legacy is honored by many institutions and awards, a pattern that continues to expand.¹

Franklin's story has been told in books such as 'The Dark Lady of DNA' by Brenda Maddox, which brought her life and work to a wide popular audience. A play, 'Photograph 51', by Anna Ziegler, portrays Franklin's life, focusing on her time at King's and the events surrounding Photo 51. Franklin was portrayed by Nicole Kidman in the London production of 'Photograph 51', bringing her story to the stage with a high-profile cast. These cultural works have helped cement her place in public memory.¹

While Franklin is best known for her DNA work, her scientific contributions extended across multiple fields. Her work on coal helped classify coals and understand their structure, and she published a paper on the structure of coal in 1950. Her coal research was not merely a prelude to her later work but a substantive contribution in its own right. She was an expert in X-ray crystallography, a skill she applied to coal, DNA, and viruses with equal rigor.¹

In virology, Franklin's work on the tobacco mosaic virus revealed its helical structure, and she showed that the virus's protein coat was helical. This finding was a significant advance in understanding the architecture of viruses. Her work on viruses contributed to the understanding of their structure, and her virus work laid the foundation for structural virology. The techniques she developed and refined at Birkbeck influenced a generation of structural biologists.²

Franklin's X-ray diffraction images are among the most famous in science, and her data indicated that DNA had a repeating structure. She measured the distances between repeating units in DNA, and her measurements were consistent with the double helix model. Her rigor in measurement and her careful interpretation of diffraction patterns set a standard for the field. She was a pioneer in the use of X-ray crystallography to study biological molecules.³

The Rosalind Franklin Papers are held at the National Library of Medicine, ensuring that primary sources documenting her work remain accessible to historians and scientists. Her paper in Nature appeared in the same issue as Watson and Crick's, a coincidence of publication that has been analyzed extensively. Franklin's paper in Nature provided evidence for the helical structure of DNA, and her work on DNA was published in a series of papers in Nature in 1953. The archival record allows for a detailed reconstruction of her scientific contributions.¹¹

Franklin's contribution to the discovery of the double helix was significant, and her data was crucial for Watson and Crick's model of DNA. She played a critical role in the discovery of the DNA double helix, a role that has been increasingly recognized in scholarly and popular accounts. Her data was used by Watson and Crick without her consent, a fact that has raised enduring questions about attribution and ethics in science. Franklin's early death meant that she could not participate in the later celebrations or defend her priority.¹²

Franklin was not elected a Fellow of the Royal Society; she died before such recognition could be conferred. The Royal Society later established the Rosalind Franklin Award in 2003, a form of posthumous institutional recognition. Franklin's legacy is honored by numerous institutions and awards, and the Rosalind Franklin Award is given annually by the Royal Society. These honors reflect a broader reassessment of her place in the history of molecular biology.¹³