Who Discovered DNA?

Heather Kane




The discovery of deoxyribonucleic acid, more commonly known as DNA, has been the foundation for much scientific work. This fundamental discovery was credited to James Watson and Francis Crick. Many people believe that another person, Rosalind Franklin, also played a large role in the research. How much did she contribute to the discovery? Why is her name left unrecognized? This paper will discuss her part in the search and whether her name should appear next to Watson's and Crick's as the co-discoverer of DNA.

In the early 1950s, the race to find the structure of DNA was in full swing. The search was being conducted at three different colleges. At the California Institute of Technology, Linus Pauling, one of the best physical chemists at that time, proposed his first DNA model, which was based more on common sense rather than mathematical reasoning [Judson, 1986]. Although he was interested in DNA, he didn't seem to realize the importance of the "golden gene" [Watson, 1968]. He was behind scientists in England as a result of not being in close contact with them. At the Cavendish in Cambridge, England, Watson and Crick were studying together. Watson was doing postdoctoral work, and Crick was working toward his doctorate. Their assignment was finding the structure of hemoglobin, not DNA. At King's College in London, Maurice Wilkins was also trying to study the DNA molecule. His professor and he agreed that they needed an x-ray specialist to aid them in their search. Rosalind Franklin was the specialist whom they chose to bring to King's College because she could make excellent x-ray despite using poor equipment ["Tribute," 1987].

In 1951, Watson attended a lecture that Franklin was giving to her co-workers on her work thus far with DNA. There on an invitation from Wilkins, he "stared at her pop-eyed and wrote down nothing" [Judson, 1986]. Two weeks later, Watson and Crick announced that they had completed a model of DNA. Franklin and a group of her colleagues traveled to Cambridge to see this model. When Franklin saw it, she all but laughed out loud. Watson had based this model on a value that he had remembered from her lecture along with his and Crick's previous knowledge of DNA, but the value of that he "remembered" was wrong. Watson's lapse of memory resulted in an impossible model that caused a great deal of embarrassment to Watson, Crick, and the rest of their staff. After this incident, the professor at Cavendish told Watson and Crick to drop the search for the DNA structure because the search belonged to the scientists at King's.

To the south, things were not going well at King's. Maurice Wilkins and Rosalind Franklin had been arguing since the day she arrived there. According to an article in Science Digest by Horace Freeland Judson [1986], "Wilkins told her that the strong cross suggested that the molecule was helix. She told him that he was jumping to conclusions." Eventually, Franklin simply shut Wilkins out of her work and she worked alone. Although she didn't realize it then, this inability to get along with Wilkins was a major factor in Watson and Crick's success.

Wilkins took his frustrations to an old friend, Francis Crick. He soon became good friends with Watson, too. They became so close that Wilkins was eventually passing on Franklin's information to Watson [Judson, 1986]. In one such case, Watson was visiting King's and had a confrontation with Franklin. When he started to lecture her on helical structures, she became very upset. A serious argument was about to break out when Wilkins walked in and escorted Watson out of the room. Wilkins took Watson down the hall and led him into another room where he showed Waston a copy of Franklin's latest and best x-ray of DNA. Franklin had no idea that this transaction, in which a vital piece of information was given away, ever took place.

Franklin inadvertently gave away other information. Not long before her run-in with Watson, all of the people at King's were required to do a short essay detailing the work that they had done so far on their projects. Franklin and her new lab assistant, Raymond Gossling, wrote five paragraphs on their studies. This paper, which was never confidential, was distributed throughout the lab. Eventually this document made its way to Cavendish and to Watson and Crick. Watson and Crick were now armed with the major accomplishments of Franklin's data.

Watson and Crick had just as much information as Franklin did without performing any experiments. They were working on finding the structures of other molecules, such as hemoglobin. Although they didn't experiment on DNA, what they did do was talk. The combination of these intellectual conversations along with their work on molecules with similar structures kept them ahead of the others [Hall, 1993]. They were also not as stubborn as Franklin and were willing to jump to the conclusions faster.

Franklin was hung up for nine months on the fact that she had photographed two different forms of DNA and was convinced that she had two different structures. The A form had been photographed after the DNA molecule had dehydrated and already started to break down. The B form had been photographed in a humid environment and was much more like its form while in a human being [Judson, 1986]. Franklin was sure that at least the A form wasn't a helical structure. After the nine months, she sat down and in only a few hours figured out what had stumped her for so long. She did the math, considered the helix as a possible structure, and quickly realized that it was the only possible structure for both the A and B forms. Shortly after receiving Franklin's superb x-ray photograph, Watson and Crick once again assembled everyone at Cambridge to display their model of DNA. According to the same article by Judson [1986], Franklin's reaction was as follows:

Franklin immediately recognized the essential facts of the structure. They are few. The two backbones are on the outside, coiled up and down around a common axis. The double helix is 20 angstrom units in diameter (79 billionths of an inch). The backbones hook themselves together again and again, across the middle, by joining molecular units called bases. The pair of bases are 3.4 angstroms apart, and the helix makes a complete turn in 10 pairs, 34 angstroms.

Franklin came very close to realizing this structure. In fact, she had already started to document her work, convinced of the structure; however, there were two key things that she missed. These two things were things she failed to see in her own data, but that Watson and Crick picked up on. The first of the two, which Crick noticed, was the fact that the two strands of DNA run in opposite direction of one another: One goes up and the other goes down. Franklin would have put both strands running in the same direction. Crick picked up on this point from a technical similarity in DNA and the hemoglobin that he was working on [Judson, 1986]. The second point, which Watson discovered, was the unique pairing of the bases in DNA. They are set up such that each strand is complementary to the other and if the two were to be separated, each half could be used to form the other strand. The four elements of the gene are placed such that adenine was paired only with thymine and cytosine only with guanine [Hall, 1993].

When it came time to hand out credit to assisting scientists, Watson and Crick were somewhat stingy. In their letter to the periodical Nature in April of 1953, their last sentence states, "We have also been stimulated by a knowledge of the general nature of the unpublished results and ideas of Dr. M. H. F. Wilkins, Dr. R. E. Franklin, and their co-workers at King's College, London" [Judson, 1986].

Now, however, Watson and Crick don't deny the fact that Franklin did play a large role in their discovery. In an article by Stephen Hall in 1993 about the fortieth anniversary of the discovery of DNA, Watson was quoted as saying, "[Franklin] would have been famous for having found DNA if she'd just talked to Francis [Crick] for an hour." The fact that Franklin didn't talk to anyone, her unwillingness to build models, and her stubborness in sticking to classical mathematics held her back immensely [Judson, 1986].

After everything was said and done, Franklin was surpirsingly not bitter. She and Crick became good friends professionally and personally [Judson, 1986]. She was offered the chance to be a senior member of the Cambridge unit's scientific staff, but she had recently learned that she had cancer and was too ill to accept. She spent her last recuperation with Crick and his family and died in April of 1958 at the age of thirty-seven. Four years after her death, in 1962, the Nobel Prize in Physiology and Medicine was given to Watson, Crick, and Wilkins. Since the Nobel Prize is never awarded to anyone after his or her death, it can never be known if Franklin could or would have gotten this honor. Many people believe that she should have. Are they right?

Several articles have been written on this very question. Some of them basically state that had she been alive, Franklin would have received the Nobel Prize. They also say that she was "ripped off" and that Watson and Crick were "data pirates." Many articles address the possibility that Franklin was sexually discriminated against because she was a woman in a man's world. All of these articles have one thing in common. They all assert that Rosalind Franklin was an extraordinary scientist and experimentalist and that she didn't receive the appropriate credit for her work.

An article on the Internet about Rosalind Franklin said that she "gave experimental backing for the double helix of DNA" ["Rosalind," 1995]. It also tells how the Nobel Prize was given to Watson, Crick, and Wilkins, "giving no credit to Franklin for her invaluable work" ["Rosalind," 1995]. In her book, Rosalind Franklin and DNA, Ann Sayre [1975] describes Franklin's work with DNA this way:

When Rosalind was confronted with DNA--an amorphous substance, difficult to handle experimentally, tiresomely recalcitrant from a crystallographer's view, requiring acute perceptiveness, if the scanty data it provided were to be interpreted at all--she was neither experienced, nor lacking in the needed arts and instincts. And it was DNA that she encountered when she went to King's College.
Another article describes her as a "gifted experimental crystallographer who was an unwitting participant in the most famous competition in 20th century science" ["Tribute," 1987]. This information suggests that similar to great artists, Franklin's value wasn't truly realized until after her death and by people who didn't personally know her. She was not always thought of quite so highly during her life. One of her co-workers at King's College said that she "didn't seem to want to mix...Her manner and speech was rather brusque and everyone automatically switched-off, clammed-up and obviously never got to know her" [Judson, 1986]. In his book The Double Helix, Waston [1968] says this of her:

By choice she did not emphasize her feminine qualities. Though her features were strong, she was not unattractive and might have been stunning had she taken even a mild interest in clothes. This she did not. There was never lipstick to contrast with her straight black hair, while at the age of thirty-one her dresses showed all the imagination of English blue-stocking adolescents.
Watson also implies that Franklin's scientifical thinking was completely wrong. It's quotes like this one that lead people to believe that "Rosy," as Watson, Crick, and Wilkins referred to her from a distance, was sexually discriminated against.

Another article in 1987 ["Tribute," 1987] bluntly states that women were unwelcome at King's College, Judson's article [1986] refutes this argument almost completely. In his research, he found that of the thirty-one scientists at King's, ten were women. Two had died by the time the article was written, Franklin being one of them. Of the other eight, Judson was able to track down and correspond with seven. All seven agreed that women were treated equitably in the lab. The senior biological advisor, Dame Honor Fell, said that she never saw a sign of sex discrimination, although Franklin and Wilkins were both rather difficult characters. Fell is sure, though, that if there were any signs of discrimination, she would have seen them. Another member of the staff, Mary Fraser, wrote that each person was accepted as a scientist, regardless of his or her sex. Still another woman claimed that the unit was completely non-biased. Perhaps Franklin was accepted as a person at King's, but Watson seemed to be more concerned about her absence of feminine qualities than her qualifications as a scientist. Although good and bad things were said about Franklin, the truth comes down to this: Rosalind Franklin was denied the Nobel Prize not because she was a woman, but because she was no longer living.

Does Franklin deserve the credit for finding the structure of DNA? Could she have gotten it first? Watson was working with a photograph shown to him on a breach of faith and with other information that Franklin didn't know he had. Would she have worked harder and faster if she had known how close her competition was? Even if she had, would she have gotten the right structure? She was unable to perceive that the strands run in opposite directions. She waited much too long to accept the helix as the structure and hadn't begun to understand how to pair the bases. She was already documenting her work, not including these vital facts. It took Watson and Crick to find these fine points in the structure.

Franklin's name wasn't omitted completely from the documents of Watson and Crick. She was mentioned, but not nearly to the extent that I feel she deserved. Considering that it was her data that they used to base their structure on. she should have at least been pointed out specifically for the excellent x-ray photograph of the B form of DNA. Instead, her name is merely an afterthought at the end of their document. She cannot be given full credit for this discovery because she didn't correctly interpret her own data. Her idea of what the structure was like was not perfect. Watson and Crick's idea already was. A discovery can't be credited to whoever came in a close second. But Rosalind Franklin did have the experimental back-up for Watson and Crick's model, and this substantial contribution to modern science should never be forgotten.


References

Hall, Stephen, "Old School Ties: Watson, Crick, and 40 Years of DNA," Science , vol.259 (March 1993), pp1532-3.

Judson, Horace Freeland, "The Legend of Rosalind Franklin," Science Digest , vol.94 (January 1986), pp. 56-59+.

"Rosalind Franklin (1920-1958)," http://curie.che.virginia.edu/layout.html (October 1995).

Sayre, Anne, Rosalind Franklin and DNA (New York: W.W. Norton &Co., 1975).

"Tribute to a Forgotten Pioneer," New Scientist, vol.115 (September 1987), pp. 71-72.

Watson, James D., The Double Helix (New York: Atheneum Publishers, 1968).


Author's Note: Heather Kane is a sophomore in chemical engineering at the University of Wisconsin at Madison. This essay arose from her EPD 155 class. (Back to Beginning)