A Brief Introduction to the Unsung Architect of Modern Biology
A short paper published in the scientific journal Nature in April 1953 changed humanity’s understanding of biology forever. The double-helix model of DNA was developed by James Watson and Francis Crick. Nobel Prize-winning discoveries in 1962 led them to unlock the molecular code of heredity.
Despite this triumphant breakthrough, modern science cannot ignore one of its most controversial chapters. Their discovery was made possible by a brilliant physical chemist named Rosalind Franklin, who took a precise X-ray diffraction photograph of DNA. As a result of her meticulous experimentation, the double-helix model could be constructed based on the critical mathematical measurements.
A tragic event occurred when Franklin’s famous photograph and experimental data were shown to Watson and Crick without her knowledge or consent. It took her four years before she was awarded the Nobel Prize for ovarian cancer in 1958, when she was 37.
You’re in the right place if you’ve ever wondered how someone else’s work can be used to make a groundbreaking scientific discovery without proper credit. Franklin’s early scientific training, her groundbreaking experimental achievements, the crucial data leak, and the ongoing efforts to restore her rightful place in history are discussed in this article.
Physical Chemistry in Early Childhood: Developing Precision
The Cambridge University Academic Excellence Award
Her parents were wealthy and politically active British Jews who lived in London in the 1920s. She showed an exceptional aptitude for science and mathematics at an early age, choosing her career path even while still in secondary school.
As a student of chemistry and physical chemistry, she enrolled at Newnham College, Cambridge, in 1938. At the time, Cambridge was a rigorous testing ground, particularly for women scientists who weren’t yet granted university degree status on an equal footing with men.
The limitations of her educational environment did not prevent Franklin from earning first-class honors on her final examinations in 1941. As a result of her academic success, she developed a career that was characterized by absolute precision, experimental rigor, and empirical evidence.
Understanding coal and carbon structure
Franklin contributed directly to the war effort during World War II by researching coal and charcoal’s physical structure. As a researcher for the British Coal Utilisation Research Association, she studied how micropores affect carbon fuel density and burn efficiency.
A Cambridge doctorate and a number of foundational papers were the results of her research. A more important lesson was how to measure amorphous substances’ invisible internal geometry.
Jacques Mering mentored Franklin at Laboratoire Central des Services Chimiques du Etat in 1947. X-ray diffraction, which maps the atomic arrangement of crystalline molecules by using X-ray beams directed at crystalline molecules, was a specialty of Mering’s.
It was during Franklin’s four years in Paris that she perfected X-ray crystallography. As a result, she was able to orient delicate fibers, control the humidity level in the environment, and interpret intricate mathematical patterns in diffraction photographs. Her colleagues recalled her as an experimentalist with a passion for precision and a refusal to speculate on theories without evidence.
King’s College London’s DNA Challenge
Join the Biophysics Unit
Rosalind Franklin returned to England in January 1951 to join the Medical Research Council Biophysics Unit at King’s College London. A laboratory directed by John Randall recruited Franklin specifically for her experience in X-ray diffraction of biological fibers, including DNA.
In those days, scientists knew DNA was a vital component of cell nuclei, but its three-dimensional structure remained a mystery. Scientists considered resolving the structure one of the holy grails of mid-century science, since it would reveal how genetic information is stored and copied.
Upon arriving at King’s College, Franklin thought she would lead the X-ray investigation of DNA independently, assisted by a graduate student named Raymond Gosling.
Maurice Wilkins and friction and miscommunication
Within the laboratory, friction was immediately caused by a major organizational misunderstanding. When Franklin joined the department, Maurice Wilkins, a senior biophysicist at King’s College who had worked on DNA before Franklin, was away.
Upon his return, Wilkins assumed Franklin had been hired as an assistant to work under his supervision. He treated Wilkins more like a colleague than as a supervisor, having grown up in a Paris laboratory that valued professional equality and open intellectual discourse.
A deep professional and personal rift resulted from this miscommunication. The two scientists had starkly different personalities. Franklin was direct, intensely focused, and insisted on strict empirical boundaries before making conclusions, while Wilkins was quiet, deliberate, and preferred speculative ideas.
Instead of collaborating smoothly, they divided the work. While Franklin studied DNA fibers using advanced X-ray equipment that she helped design, Wilkins studied structural biology.
Photo 51: The Experimental Breakthrough
The discovery of DNA forms A and B
Franklin made a significant discovery that had eluded previous researchers shortly after beginning her work at King’s College. According to her research, DNA exists in two different structural forms depending on the relative humidity of the environment in which the sample was obtained.
DNA fibers assumed a compact form when dry, which she called the A-form. The molecule absorbed water, elongated, and converted into a distinct structure that she termed B-form when hydrated.
As a result of capturing both forms simultaneously, previous researchers produced blurry, inconclusive X-ray images. Franklin isolated pure samples of both the A-form and B-form by carefully controlling the humidity inside her camera chamber.
Take the definitive picture
A remarkable X-ray diffraction photograph of DNA’s hydrated B-form was captured by Franklin and her graduate student Raymond Gosling in May 1952. A custom-built chamber filled with hydrogen gas was used to minimize scattering over a period of over 100 hours.
The resulting photograph was titled Photo 51.
The experimental techniques used in Photo 51 were masterpieces to a trained crystallographer. In the center of the dark X-pattern, a helical structure can be clearly seen. Using the spacing and intensity of the diffraction spots, direct mathematical measurements could be made.
- Helix width was approximately 2 nanometers.
- A complete turn of the helix takes 3.4 nanometers.
- Each turn had 10 bases, since the distance between adjacent molecular bases was 0.34 nanometers.
- The sugar-phosphate backbone of the molecule had to be on the outside of the structure in order to interact with the surrounding water molecules.
She documented these measurements in her laboratory notebooks, methodically working through the mathematical transformations required to prove the helical parameters.
What Data Traveled to Cambridge: Unfettered Access
Unauthorized Display of Photo 51
At the Cavendish Laboratory at Cambridge University, Franklin was quietly finalizing her DNA structure analysis while working at King’s College. On the basis of theoretical chemistry and public data, James Watson and Francis Crick attempted to build physical scale models of DNA.
Model building had been stymied by incorrect assumptions in the early stages. During a public lecture given by Franklin in late 1951, Watson remembered her measurements incorrectly, which led Crick to construct an embarrassing triple-helix model with the phosphates on the inside. They were ordered to cease building DNA models by their department head after Franklin publicly criticized their model at Cambridge.
American chemist Linus Pauling published a paper proposing a three-stranded model for DNA in late 1952 or early 1953, which led to increasing urgency.
In January 1953, Maurice Wilkins showed Photo 51 to James Watson at King’s College. A competing research team was unaware that Franklin’s photograph was being shown.
When Watson saw Photo 51 for the first time, he immediately became shocked and his pulse accelerated: “A clear X-shape stood out on the film, revealing a helix,” he wrote in his 1968 memoir The Double Helix. The pattern was much simpler than those obtained previously.
Leak of Medical Research Council report
For Watson and Crick to build an accurate model, Franklin’s precise quantitative calculations were still needed.
A formal administrative channel was used to obtain that missing data shortly thereafter. Cavendish Laboratory researcher Max Perutz served on a Medical Research Council committee that evaluated the performance of government-funded research units.
Her unpublished experimental results, unit cell dimensions, and symmetry calculations for DNA’s B-form were detailed in Franklin’s December 1952 progress report to the committee.
This committee report was presented to Francis Crick by Perutz in 1953. Perutz assumed the report was common knowledge among the researchers because it was not marked confidential.
As a result of Franklin’s precise spatial coordinates and symmetry measurements, Crick discovered that the two chains of the helix ran in opposite, anti-parallel directions. Watson and Crick completed their iconic double helix model within weeks, which incorporated complementary base pairings on either side of a sugar-phosphate backbone.
Publication and erasure of contributions
Nature Papers, April 1953
During April 1953, Nature published three articles on nucleic acid structure back-to-back:
- In this paper, Watson and Crick present the model of the double helix.
- A supporting paper by Wilkins and his colleagues discussing X-ray evidence in general.
- Rosalind Franklin and Raymond Gosling present Photo 51 and quantitative analysis supporting the B-form helix.
First published, Watson and Crick’s paper gave the impression that Franklin’s supporting data confirmed their theoretical model, rather than building on it.
In addition, Watson and Crick only acknowledged Franklin and Wilkins in a footnote, stating they had been “stimulated by a general knowledge” of their research at King’s College. Her diffraction photograph and detailed Medical Research Council report were not disclosed.
Pioneering virus research at Birkbeck
The unwelcoming work environment at King’s College London had already led Franklin to leave before the Nature papers appeared. Her research fellowship was transferred to Birkbeck College under the direction of renowned physicist J.D. Bernal.
King’s told her to cease working on DNA altogether before she left, leaving her data behind.
Franklin turned her crystallographic expertise to plant viruses, including the Tobacco Mosaic Virus and Poliovirus. During the next five years, she established an international reputation for her work on virus structure.
The Birkbeck team demonstrated that the Tobacco Mosaic Virus is a hollow tube wrapped in a helical coat of protein RNA, setting a new benchmark for structural virology. A productive laboratory manager, she mentored young scientists like Aaron Klug, and presented her research internationally.
The 1962 Nobel Prize and a tragic death
A Life Cut Short
Franklin began experiencing severe abdominal pain while on a research trip in the United States in 1956. The diagnosis of terminal ovarian cancer was made once she returned to England.
Despite undergoing multiple surgeries and chemotherapy treatments, she worked in her laboratory until she died. During her illness, she published 13 papers on virus structures, secured research funding, and supported her team.
At the age of 37, Rosalind Franklin passed away on April 16, 1958.
Exclusion from the Nobel Prize
In 1962, James Watson, Francis Crick, and Maurice Wilkins were jointly awarded the Nobel Prize in Physiology or Medicine for their discoveries about nucleic acids’ molecular structure.
Nobel Prizes are not awarded posthumously under the official statutes of the Nobel Foundation. The award could not be given to Franklin because she had passed away four years earlier.
Watson’s 1968 memoir, however, dominated the public narrative of the discovery, portraying Franklin in a patronizing light, referring to her by the nickname “Rosy” and underplaying her own experimental findings.
Her original laboratory notebooks and correspondence were examined only decades later by historians, biographers, and fellow scientists, revealing the extent of her contributions.
Bringing Rosalind Franklin back into the historical spotlight
Observations based on the historical record
Historical analysis of Franklin’s laboratory notes reveals several facts that challenge early caricatures:
- In fact, Franklin was not anti-helical; she knew the B-form of DNA was a double helix before Watson and Crick created their model.
- In her calculations, she correctly determined that the phosphate groups must be situated on the outside of the molecule, which Watson and Crick had failed to realize.
- Crick deduced the anti-parallel nature of the two strands from her mathematical calculations regarding the crystalline space group.
- The double helix would not have been discovered without her experimental mastery in producing Photo 51.
Her memory has been honored by scientific institutions worldwide in recognition of her pivotal contributions. A life sciences building was named after her at King’s College London, the Rosalind Franklin Award was established by the Royal Society, and the Rosalind Franklin Mars rover was named after her by the European Space Agency.
The key takeaways for science and ethics
Rosalind Franklin’s contributions to chemistry and biology go beyond her structural contributions. The story of her professional persistence, institutional recognition, and ethical behavior is an enduring lesson in scientific ethics:
- Data Integrity and Attribution: The advancement of science is dependent on transparency of attribution. The scientific community does not trust unpublished experimental data that has not been explicitly consented to or credited.
- A theoretical model is only as valid as the empirical data it is based upon. Biochemical models were based on Franklin’s dedication to high-quality data collection.
- Achieving Professional Excellence: Franklin maintained high standards of professional excellence despite systemic barriers against female researchers.
- A Broad Scientific Legacy: Franklin was far more than a contributor to DNA discovery; her foundational work on coals, carbons, and virus structures made lasting contributions to physical chemistry and structural virology.
Despite her tragically short life, Roselind Franklin made a lasting contribution to modern science. The discovery of DNA’s structural secrets led to the advent of modern genetics, forever changing human understanding of life.
