James Dewey Watson, KBE (hon.), ForMemRS, (born April 6, 1928) is an American molecular biologist, geneticist and zoologist, best known as a co-discoverer of the structure of DNA in 1953 with Francis Crick. Watson,
Francis Harry Compton Crick, OM, FRS (8 June 1916 – 28 July 2004) was an English molecular biologist, biophysicist, and neuroscientist, most noted for being a co-discoverer of the structure of the DNA molecule in 1953 with James Watson.
focus their education, talents, and skills on political, educational, and charitable forms of community service. It was thus surprising when young Rosalind expressed an early fascination with physics and chemistry classes at the academically rigorous St. Paul’s Girls’ School in London, and unusual that she earned a bachelor’s degree in natural sciences with a specialty in physical chemistry. The degree was earned at Newnham College, Cambridge in 1941.
From 1942 to 1946, Franklin did war-related graduate work with the British Coal Utilization Research Association. That work earned her a PhD from Cambridge in 1945, and an offer to join the Laboratoire Central des Services Chimiques de l’Etat in Paris. She worked there, from 1947 to 1950, with Jacques Mering and became proficient at
Rosalind Franklin was born 25 July 1920 to Muriel Waley Franklin and merchant banker Ellis Franklin, both members of educated and socially conscious Jewish families. They were a close immediate family, prone to lively discussion and vigorous debates at which the politically liberal, logical, and determined Rosalind excelled: She would even argue with her assertive, conservative father. Early in life, Rosalind manifested the creativity and drive characteristic of the Franklin women, and some of the Waley women, who were expected to
Franklin's work from another source. Her lab was funded by the Medical Research Council, which required grant recipients to report on their progress at the end of each year. All of the clues that Franklin had uncovered were summarized in that report. Such reports are supposed to be confidential, but Watson and Crick happened to know someone on the Medical Research Council who had a copy of the report and was willing to show it to them. When Crick saw the evidence in the report, he recognized the
While Watson and Crick went back to their model building, Franklin continued to work on DNA by making X-ray diffraction images and analyzing these results. She and Gosling focused on DNA A, producing many clear images and uncovering more clues to its structure: the size of the repeating units that made up the molecule and the symmetry of these units. DNA crystals, it turned out, look the same when they are turned upside down and backwards.
Each image took many hours of X-ray exposure to develop — sometimes up to 100 hours — so Franklin and Gosling occasionally exposed them overnight. On the morning of May 2nd, 1952, they returned to the lab to discover that the DNA had hydrated during the night and the image they had taken was actually of DNA B. It was unusually sharp — and illuminating. It showed an obvious x shape, a pattern that previous work associated with helical structures. The image also confirmed the idea that DNA's bases were stacked pancake-style, .34 nanometers apart, and suggested that 10 of these layers occurred in every twist of the helix. It even delineated the width of the diameter of the helix: 2 nanometers. Since it was the 51st image taken, they called it image B 51. They set it aside and decided to come back to it once they'd solved the structure of DNA A.
Notebook entries show that Rosalind Franklin (a) recognized that the B form of DNA was likely to have a two-chained helix; (b) was aware of the Chargaff ratios; (c) knew that most, if not all, of the nitrogenous bases in DNA were in the keto configuration (circles indicate the hydrogen positions that distinguish the keto from the enol form); and (d) determined that the backbone chains of A-form DNA are antiparallel. scitation.aip.org/content/aip/magazine/physicstoday/article/56/3/10.1063/1.1570771
Maurice Wilkins, the nuclear physicist, entered the race for DNA based on a stroke of luck. After his work with the Manhattan Project on atomic bombs was completed, he wanted to switch to a more peaceful line of work and was inspired to investigate the physical basis for life. He turned to the fast-growing field of biophysics, taking up a position at the University of London. Early in his career there, he happened to attend a conference where a biochemist gave away samples of high-quality DNA. Wilkins was lucky enough to get
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2. The discovery of the double helix structure of DNA.
3. Rosalind Franklin and Raymond Gosling. Without permission from Franklin, their lab director Maurice Wilkins showed it to James Watson and Francis Crick, who went on to win the 1962 Nobel Prize in Physiology or Medicine for "their" discovery.
Comments from Our Readers
Search for "photograph x-ray" revealed a similar image, which then led to a "my hero" page about Rosalind Franklin, and also led to the photograph above, which led to a multi-page site about Cambridge and the Watson/Crick/Wilkins story which credited Ms. Franklin as being a major player in the discovery. Incidentally, the closest medical school to me (20 miles) is Rosalind Franklin University Medical School, which was renamed for her in 1987.
I immediately recognized this as an X-ray diffraction pattern; a Google search for "photograph x-ray" revealed a similar image, which then led to a "my hero" page about Rosalind Franklin, and also led to the photograph above, which led to a multi-page site about Cambridge and the Watson/Crick/Wilkins story which credited Ms. Franklin as being a major player in the discovery. It is only in the last 20 years or so that her contributions to the discovery process have been fully recognized. Incidentally, the closest medical school to me (20 miles) is Rosalind Franklin University Medical School, which was renamed for her in 1987.
Picture looked like an x ray projection of some kind, It looked like a structure, so I googled xray structure discovery and a picture with wet DNA appeared, took it from there.
At first I thought it was a picture of the inside of a human eyeball. It didn't look like my eyeball, but that was the only idea I had so I ran with it. After finding nothing in any of the texts I looked at, I clicked on the images link that kept coming up. There I found a very similar photo. Someone else must have thought it looked like an eyeball, too! It’s nice to know I wasn’t alone in my way of thinking, as twisted as it turned out to be.
This was not very difficult but required some creative thinking. I thought it might be of a three dimensional object. Clever.
Your friend is correct, after years of skirting the truth and possibly giving half truths, these men probably fully believe their lies. So, unfortunately, in their minds they are not lying at all.
This one was interesting and hit home. I know what you mean about trying to be accepted into what's considered a man's field. I was in banking and finance until retirement a few years ago. I had it a little easier than Rosalind but the sexism is still going on. Just look at the problems getting the military to take sexual assaults and harassment seriously.
I think time has taken care of giving Franklin credit one way or the other. Plus, Watson still deserves a lot of merit for having figured it out by just looking at Franklin's pictures when nobody else had
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a sample — though it might not have seemed that impressive at the time.
Coffee served in crucibles was a tradition in Jacques Mering’s Paris laboratory, where Rosalind Franklin worked from 1947 to 1950. Biographer Anne Sayre reports that the time Franklin spent working in Paris was the happiest period of her life. This candid photo was taken by Vittorio Luzzati. scitation.aip.org/content/aip
Raymond Gosling, a Ph.D. student in Wilkins' lab, suggested looking at the DNA with a new observational technique called X-ray diffraction, useful for imaging crystalline structures. Although the DNA didn't look very crystalline, Gosling wanted to try X-ray diffraction on the molecule anyway. Despite a few confusing blurry spots, the images hinted that DNA might come in the form of a twisted spiral — better known as a helix - though it was still not clear how the phosphates, sugars, and bases were arrayed within that helix.
James Watson was studying biochemistry at the Naples Marine Station — but decided to devote all his time and
energy to understanding the structure of DNA. At first, he wanted to join Wilkins' lab — but Wilkins didn't have any room. Instead, in the autumn of 1951, he joined another lab specializing in X-ray diffraction, at Cambridge University. There, he shared Wilkins' and Gosling's clue about DNA with someone who would soon join him in the race for the structure of DNA, Francis Crick.
Like Wilkins, Frances Crick had started out as a physicist. Like Wilkins, Crick had started out as a physicist. During World War II, he put his scientific training to work designing underwater mines. After the war, he got interested in studying the physical basis of life and joined a Cambridge biology lab. Watson's enthusiasm for DNA was contagious. He was convinced by the published results suggesting that genes were made of DNA. And though he did not yet know that a helical structure had been suggested for DNA, he had seen the evidence from Wilkins' presentation indicating that the structure of DNA was simple enough to solve. Watson shared this evidence with Crick — who eventually decided to join the race himself.
While Francis Crick and James Watson were joining forces
Crick and Watson
at Cambridge, things were changing back in Wilkins' lab at the University of London too. The preliminary findings were exciting — they knew that DNA had a regular structure — but they still had to figure out what that structure was. Expert help was needed to improve and interpret the X-ray results. Luckily, Rosalind Franklin, a scientist who specialized in X-ray diffraction, had just joined the lab. Franklin was used to working with messy materials that came from living things — she had just finished an important study applying X-ray diffraction to coal, the compressed remains of ancient swamp plants. She was asked to lend her expertise to the DNA project, and it soon caught her imagination.
Franklin began working with Raymond Gosling, the graduate student who had encouraged Wilkins to try X-ray diffraction on his DNA sample. Over the summer of 1951, she taught Gosling the exacting X-ray diffraction techniques she'd developed. They exposed the special high-quality DNA sample to a range of different humidities, from wet to dry. In the dry atmosphere, the strands appeared to thicken, and the X-ray patterns turned into a sharp scatter with many distinct spots. As they added moisture to the atmosphere, the strands stretched, and the X-ray pattern changed to a clear x shape.
The two different patterns demonstrated that DNA existed in two
forms: the dry A form, which held less water, and the wet B form, in which water molecules cling to the DNA, causing it to stretch out. The first X-ray images of DNA taken by Wilkins and Gosling had been sharp, but they had contained a few confusing blurry spots. Franklin and Gosling's new images explained why: the previous images were based on a blend of the two forms mixed together.
The University of London group had now uncovered several important clues to DNA's structure: it was crystalline, at least one of its forms took the shape of a helix, and many water molecules could cling to it. Franklin took things one step further, fitting together a few of the existing puzzle pieces. Based on the ease with which DNA took up water, she reasoned that the phosphates (which attract water) must be on the outside of the helix.
Crick and Watson wanted to work on DNA's structure, but they couldn't approach it as
Wilkins and Franklin were — through X-ray diffraction. First, Crick was a friend of Wilkins and didn't want to step on his toes. Second, Watson and Crick didn't have the high-quality DNA samples necessary for X-ray diffraction. But Watson and Crick had another way of working — they could form hypotheses about
X-ray diffraction patterns for the two forms of DNA; at left, form A, at right, form B.
DNA's structure by building a physical model of how its atoms fit together.
In order to try model building, Crick and Watson still needed data on DNA as a starting point. As soon as they heard that Franklin was going to share her findings in a talk at the University of London, Watson made plans to go. At the presentation, Franklin showed X-ray diffraction patterns produced by DNA A and B, and discussed how the two forms seemed to be produced by surrounding the DNA molecules with different amounts of water. She also described the spacing between the atoms in DNA, based on the patterns in her diffraction images. Watson listened with interest. Yet the next day, his memory failed him when he met up with Crick to discuss the evidence Franklin had shared. In particular, he couldn't seem to remember how much water Franklin had said surrounded the molecule. Nonetheless, Crick had experience in X-ray diffraction and thought he could put the pieces together. They decided that they had enough evidence to build a model of DNA's structure.
In their model, three long twists of the sugar-phosphate chain were held together by magnesium ions, and the bases flopped outward from this central backbone. Watson and Crick excitedly invited Wilkins, Franklin, and Gosling to come see the model. When Franklin arrived, she quickly saw that Watson had remembered several things incorrectly — in particular, he had forgotten the amount of water that surrounded each strand. DNA crystals contained at least ten times as much water as their model allowed for, and there was no evidence that DNA contained any magnesium at all. If it did, all that water would cling to the magnesium ions, tearing the molecule apart. It was clear that the hypothesis Watson and Crick had formulated using their metal-and-wire models didn't fit the available evidence on DNA. It would have to be rejected.
Watson and Crick's model erroneously placed the bases on the outside of the DNA molecule with the phosphates, bound by magnesium or calcium ions, inside.
With Franklin and Gosling gathering additional evidence, and Crick and Watson concentrating on generating new hypotheses, the puzzle of DNA seemed close to being solved. But a personal conflict would soon change the course of this discovery. From the time that Franklin started working in the lab, she and Wilkins had argued about which of them would get to work on DNA. Initially, their boss had asked Wilkins to hand the project over to Franklin — so Wilkins gave her all of the high- quality DNA sample. Later, he decided he wanted to keep working on the problem anyway, but Franklin had already gotten started and didn't want to be pushed out. The resulting tension made both of them unhappy, and shortly after image B 51 was taken, Franklin notified her boss that she wanted to leave the lab. This left Gosling, her student, upset and without a Ph.D. supervisor. He decided to seek advice from Wilkins — and when he did, he took a critical piece of evidence with him: image B 51.
Wilkins had always been more interested in DNA B anyway, and he took special notice
of the clear, informative image. Later that month, Watson came to London for another lab colloquium. After the talk, Wilkins had dinner with Watson and showed him the beautiful image of DNA B produced by Franklin. Because Crick had helped Watson learn how to interpret the X-ray patterns produced by helices, Watson immediately recognized the tell-tale evidence of a helix — which he had suspected all along — as well as other clues that would help Watson and Crick put all the puzzle pieces together. Determined not to make the same mistake as before, Watson asked Wilkins for more details, and this time, he wrote everything down.
Bottles containing the high quality DNA samples that Franklin obtained from Wilkins.
When he returned to Cambridge, Watson shared the new results with Crick and they applied the information to their ball-and-stick models. Watson wanted to try making a model in which just two phosphate-sugar-base chains were linked together. He thought it made sense for genes to come in pairs, partly because most organisms have two parents. Watson and Crick also decided to try orienting the bases towards the center of the pair. Watson later recounted that they tried this approach simply because it was something they hadn't yet tried, though Franklin had previously given them good reason to think that the bases should be on the inside and phosphates on the outside of the molecule where they could attract water. Both of them were surprised by how well the new two-strand, bases-in model fit the clues Watson had scribbled down during his dinner with Wilkins. But Watson and Crick weren't the only ones thinking about a double helix — Rosalind Franklin's notes from February 10th show that she started wondering if DNA B might be a two-chain helix around the same time.
Of course, because she had produced the results, Franklin was the only one with all the data — and Watson and Crick needed more information to keep working. In science, researchers regularly share their findings with other scientists through journal publications, but Franklin's results were so new that they hadn't been thoroughly peer- reviewed and published. However, Watson and Crick were able to find out more about
type of crystal symmetry Franklin described, and realized something that she hadn't. If DNA crystals could be flipped upside down and backwards, and still look the same, the strands of the backbone must be identical, and they must run in opposite directions.
By this time, Franklin had also concluded that DNA was a two-chain helix, composed of two intertwined sugar-phosphate backbones. Figuring out the shape of the backbones, though, still left the bases an open question. She knew from details in her X- ray images that the phosphates were on the outside of the helix, which meant that the bases must point toward the center. But how did they fit together? Each base is a slightly different size, but the smooth twists of the sugar-phosphate chain never varied. How could the bases fit inside the chains without touching and repelling one another? She was sure there was a clue in DNA's unique base ratios — one of the puzzle pieces discovered before Franklin had even begun to study DNA — but she still wasn't sure exactly what that clue meant. By February 23rd, her notes show that she realized that if A were physically interchangeable with G, and C with T, then the amount of A would have to equal T, and likewise for C and G. She was getting close. Meanwhile, back in Cambridge, Watson and Crick were working on the same problem …
Watson and Crick were also stuck on what to do with the bases. At first, Watson thought they paired together A-A, C-C, T-T, G-G — but because of the different sizes of the bases, the hypothesis had to be discarded. It would have required a sugar- phosphate backbone that wiggled in and out, rather than winding around in smooth twists. Then, Watson and Crick got a key piece of evidence about the shapes of the bases from a visiting American chemist, Jerry Donohue. At that time, most chemistry
textbooks reported a particular placement of hydrogen on the bases. That placement made it impossible to match A to T, or G to C — they just didn't fit. Donohue told Watson that the textbooks were outdated. More was now known about the shapes these bases might take: one of the hydrogen atoms could be attached to the base in another location. In fact, based on a few different lines of evidence, Donohue thought that the bases likely took shapes that Watson had not yet tried.
Watson tried to fit the new shapes into the two-chain model he and Crick had developed. On February 28th, he was playing with paper cutouts of each base when he suddenly saw the answer. The A fit with T, and G fit with C. Plus, the A-T pair had the exact same molecular length as the G-C pair! Bonded together like this, the bases wouldn't bump and repel one another. Crick realized that if the bases paired up like this, it would explain the mysterious base ratios: A=T, G=C. Suddenly, it made perfect sense that the base pairs must be in the center of the molecule, and that the two sugar-phosphate strands wound around them. It even suggested how one strand could be used to copy the other. Because each base always matches up with the same partner, the order of bases on one strand could determine the exact order of bases on a new strand. Within a week, Watson and
Given the correct forms for the bases, Watson was able to figure out how adenine- thymine and guanine- cytosine pairs matched up, and formed weak hydrogen bonds with one another. Watson and Crick originally suggested that there were two bonds between guanine and cytosine but later it was found that a third existed.
Crick had worked out the details of their hypothesis about the molecular structure of DNA.
Watson and Crick published their proposed structure for DNA in April 1953 in the journal Nature.3 In the same issue, Wilkins, Franklin, Gosling, and their colleagues presented the evidence they'd collected, which supported Watson and Crick's two-chain helix hypothesis.4 In this way, the evidence and hypothesis relating to the structure of DNA entered the scientific literature and became available for other researchers to build on.
But not everything that went into these papers came from freely available sources. Scientists often use others' data and ideas, but they are expected to give credit to their
In The Double Helix, Watson bases his account of Franklin on recollections of their three brief meetings between 1951 and 1953, and on repeated complaints about her from Wilkins. The “Rosy” that Watson describes is a caricature based on the more difficult aspects of Franklin’s personality. His portrayal—a far cry from the competent scientist described by her colleagues or the fascinating person described by her friends—is an effective device for promoting the idea that Watson and Crick had to rescue DNA data from—as Watson’s book puts it— this “belligerent” woman who could not “keep her emotions under control” and who did not know how to interpret her own data. Watson falsely depicts Franklin as Wilkins’s assistant, incapable and unworthy of Nobel Prize- caliber work. His book was published against the vehement protest of key DNA participants, who were upset about its numerous inaccuracies. scitation.aip.org/content/aip
sources. This allows science to grow by building on existing ideas, while rewarding individual scientists for their contributions. Crick and Watson's paper did give credit for much of the evidence they'd collected during their investigation of the structure of DNA. However, data inspiring some of their key insights came from Franklin's 1952 report to the Medical Research Council — which was supposed to be confidential information. Franklin never gave Watson and Crick permission to use that work, and in their paper — the scientific record of this discovery — they do not credit Franklin for supplying this evidence or for image B 51, which was so critical to their discovery. Retrospectively, both Crick and Watson acknowledged their debt. According to Crick, "all the really relevant experimental work on the X-ray diffraction patterns of DNA" came from Franklin's lab, and Watson later claimed that their discovery would not have been possible without the data collected by Franklin.
The failure to give full credit to important evidence is considered a serious infringement of scientific ethics. Crick and Watson have both had highly successful scientific careers, but the issue of whether or not they acted fairly has continued to follow them. In interviews and public appearances, they were — and are — frequently questioned about their choices and about Franklin's role in their most famous discovery, and have had to endure the scrutiny and judgment of the scientific community.
It's also worth noting that Franklin was a pioneer in terms of women's presence in the sciences. At the time Franklin was working on DNA, less than five percent of Ph.D.s in the physical sciences were awarded to women.5 Franklin never reported specific examples of discrimination (aside from not being allowed to eat with her male colleagues in the senior common room), but she did worry that her work might not be taken seriously because of her gender. Though we can never know for sure, it's certainly possible that the discovery of DNA's structure — and the credit given for it — would have played out differently, had the social environment for women scientists been fairer.
After unraveling the structure of DNA, all four researchers continued to study genetics and molecular biology, although along their separate paths. Wilkins, Watson, and Crick went on to collect additional evidence on DNA's structure, examine how DNA copies itself, and investigate the genetic code inherent in the DNA molecule. Sadly, Franklin's research was cut short when she died of cancer — just five years after the landmark Nature publication. This also meant that Franklin missed out on many of the honors awarded for their discovery, including the possibility of a Nobel Prize — which cannot be awarded posthumously.
Despite her early death, Franklin's work, along with that of the others, has earned a permanent place in our accumulated scientific knowledge. Genetic researchers today still build on the foundation laid by these half-century old ideas and findings. If we trace the roots of today's cutting-edge technologies like DNA fingerprinting, genetic engineering, and genome sequencing back in time, we will
find ourselves once again in the X-ray diffraction lab at the University of London and tinkering with models at Cambridge. And continuing even further back in time, we'll encounter the community of researchers who set the stage for this discovery by developing X-ray diffraction techniques and by uncovering those first puzzle pieces that inspired Wilkins, Franklin, Watson, and Crick to join the race and chase down the double helix. With many open questions involving DNA, its structure will continue to be a key piece of evidence in many new discoveries yet to come.
applying x-ray diffraction techniques to imperfectly crystalline matter such as coal. In the period 1946– 49, she published five landmark coal-related papers, still cited today, on graphitizing and nongraphitizing carbons. By 1957, she had published an additional dozen articles on carbons other than coals. Her papers changed the way physical chemists view
The Tuscan landscape forms the background of this photograph of Rosalind Franklin, taken in the spring of 1950 by her friend Vittorio Luzzati. scitation.aip.org/content
the microstructure of coals and related substances.
Franklin made many friends in the Paris laboratory and often hiked with them on weekends. She preferred to live on her own modest salary and frustrated her parents by continually refusing to accept money from them. She excelled at speaking French and at French cooking and soon became more comfortable with intellectual and egalitarian “French ways” than with conventional English middle- class customs. Consequently, she did not fit in well at King’s College, where she worked on DNA from 1951 to 1953. Franklin chose to leave King’s and, in the spring of 1953, moved to Birkbeck College. Many of the students there were evening students who worked during the day, and Franklin was impressed with their dedication. After the move to Birkbeck, she began her celebrated work with J. Desmond Bernal on RNA viruses like tobacco mosaic virus (TMV). She was a cautious scientist who began to trust her intuition more as she matured (see box 1 on page 45). She published 14 papers about viruses between 1955 and 1958, and completed the research for three others that colleague Aaron Klug submitted for publication after her death.
In his obituary for Franklin, Bernal described her as a “recognized authority in industrial physico-chemistry.” In conclusion, he wrote, “As a scientist, Miss Franklin was distinguished by extreme clarity and perfection in everything she undertook. Her photographs are among the most beautiful of any substances ever taken.”
In mid-1956, while on a work-related trip to the United States, Franklin first began to suspect a health problem. An operation in
September of the same year revealed two tumours in her abdomen. After this period and other periods of hospitalization, Franklin spent time convalescing with various friends and family members. These included Anne Sayre, Francis Crick, his wife Odile, with whom Franklin had formed a strong friendship, and finally with the Roland and Nina Franklin family where Rosalind's nieces and nephews bolstered her spirits.
Franklin chose not to stay with her parents because her mother's uncontrollable grief and crying upset her too much. Even while undergoing cancer treatment, Franklin continued to work, and her group continued to produce results – seven papers in 1956 and six more in 1957. In 1957, the group was also working on the polio virus and had obtained funding from the Public Health Service of the National Institutes of Health in the United States for this.
At the end of 1957, Franklin again fell ill and she was admitted to the Royal Marsden Hospital. She returned to work in January 1958, and she was given a promotion to Research Associate in Biophysics.She fell ill again on March 30, and she died on April 16, 1958, in Chelsea, London, of bronchopneumonia, secondary carcinomatosis, and ovarian cancer. Exposure to X-ray radiation is sometimes considered to be a possible factor in her illness.Other members of her family have died of cancer, and the incidence of gynaecological cancer is known to be disproportionately high among Ashkenazi Jews.
Her death certificate read: A Research Scientist, Spinster, Daughter of Ellis Arthur Franklin, a Banker.