James Watson, Francis Crick, Maurice Wilkins,
and Rosalind Franklin
These four
scientists—Watson, Crick, Franklin, and Wilkins—codiscovered the double-helix
structure of DNA, which formed the basis for modern biotechnology.
At King’s College London, Rosalind Franklin obtained images of DNA using
X-ray crystallography, an idea first broached by Maurice Wilkins. Franklin’s
images allowed James Watson and Francis Crick to create their famous
two-strand, or double-helix, model.
In 1962 Watson (b. 1928), Crick (1916–2004), and Wilkins (1916–2004)
jointly received the Nobel Prize in Physiology or Medicine for their 1953
determination of the structure of deoxyribonucleic acid (DNA). Wilkins’s
colleague Franklin (1920–1958), who died from cancer at the age of 37, was not
so honored. The reasons for her exclusion have been debated and are still
unclear. There is a Nobel Prize stipulation that
states “in no case may a prize amount be divided between more than three
persons.” The fact she died before the prize was awarded may also have been a
factor, although the stipulation against posthumous awards was not instated
until 1974.
Discovering the Structure of DNA
The
molecule that is the basis for heredity, DNA, contains the patterns for
constructing proteins in the body, including the various enzymes. A new
understanding of heredity and hereditary disease was possible once it was
determined that DNA consists of two chains twisted around each other, or double
helixes, of alternating phosphate and sugar groups, and that the two chains are
held together by hydrogen bonds between pairs of organic bases—adenine (A) with
thymine (T), and guanine (G) with cytosine (C). Modern biotechnology also has
its basis in the structural knowledge of DNA—in this case the scientist’s
ability to modify the DNA of host cells that will then produce a desired
product, for example, insulin.
The
background for the work of the four scientists was formed by several scientific
breakthroughs: the progress made by X-ray crystallographers in studying organic
macromolecules; the growing evidence supplied by geneticists that it was DNA,
not protein, in chromosomes that was responsible for heredity; Erwin Chargaff’s
experimental finding that there are equal numbers of A and T bases and of G and
C bases in DNA; and Linus Pauling’s
discovery that the molecules of some proteins have helical shapes—arrived at
through the use of atomic models and a keen knowledge of the possible
disposition of various atoms.
Rosalind Franklin in Paris.
Vittorio Luzzati
Rosalind Franklin
Of
the four DNA researchers, only Rosalind Franklin had any degrees in chemistry.
She was born into a prominent London banking family, where all the
children—girls and boys—were encouraged to develop their individual aptitudes.
She attended Newnham College, one of the women’s colleges at Cambridge
University. She completed her degree in 1941 in the middle of World War II and
undertook graduate work at Cambridge with Ronald Norrish, a future Nobel
laureate. She resigned her research scholarship in just one year to contribute
to the war effort at the British Coal Utilization Research Association. There
she performed fundamental investigations on the properties of coal and
graphite. She returned briefly to Cambridge, where she presented a dissertation
based on this work and was granted a PhD in physical chemistry. After the war,
through a French friend, she gained an appointment at the Laboratoire Centrale
des Services Chimiques de l’Etat in Paris, where she was introduced to the
technique of X-ray crystallography (see video on this page) and rapidly became
a respected authority in this field. In 1951 she returned to England to King’s
College London, where her charge was to upgrade the X-ray crystallographic
laboratory there for work with DNA.
Maurice
Wilkins
Maurice
Wilkins with X-ray crystallographic equipment about 1954.
King’s
College London and Horace Freeland Judson
Already
at work at King’s College was Maurice Wilkins, a New Zealand–born but
Cambridge-educated physicist. As a new PhD he worked during World War II on the
improvement of cathode-ray tube screens for use in radar and then was shipped
out to the United States to work on the Manhattan Project. Like many other
nuclear physicists, he became disillusioned with his subject when it was
applied to the creation of the atomic bomb; he turned instead to biophysics, working
with his Cambridge mentor, John T. Randall—who had undergone a similar
conversion—first at the University of St. Andrews in Scotland and then at
King’s College London. It was Wilkins’s idea to study DNA by X-ray
crystallographic techniques, which he had already begun to implement when
Franklin was appointed by Randall. The relationship between Wilkins and
Franklin was unfortunately a poor one and probably slowed their progress.
James Watson and Francis Crick
Meanwhile,
in 1951, 23-year-old James Watson, a Chicago-born American, arrived at the
Cavendish Laboratory in Cambridge. Watson had two degrees in zoology: a
bachelor’s degree from the University of Chicago and a doctorate from Indiana
University, where he became interested in genetics. He had worked under
Salvador E. Luria at Indiana on bacteriophages, the viruses that invade
bacteria in order to reproduce—a topic for which Luria received a Nobel Prize
in Physiology or Medicine in 1969. Watson went to Denmark for postdoctoral
work, to continue studying viruses and to remedy his relative ignorance of
chemistry. At a conference in the spring of 1951 at the Zoological Station at
Naples, Watson heard Wilkins talk on the molecular structure of DNA and saw his
recent X-ray crystallographic photographs of DNA. He was hooked.
James
Watson and Francis Crick with their DNA model at the Cavendish Laboratories in
1953. To request permission to use this photo, please visit the Science
Photo Library website at www.photoresearchers.com.
©
A. Barrington Brown.
Watson
soon moved to the Cavendish Laboratory, where several important X-ray
crystallographic projects were in progress. Under the leadership of William
Lawrence Bragg, Max Perutz was
investigating hemoglobin and John Kendrew was studying myoglobin, a protein in
muscle tissue that stores oxygen. (Perutz and Kendrew received the Nobel Prize
in Chemistry for their work in the same year that the prize was awarded to the
DNA researchers—1962.) Working under Perutz was Francis Crick, who had earned a
bachelor’s degree in physics from University College London and had helped
develop radar and magnetic mines during World War II. Crick, another physicist
in biology, was supposed to be writing a dissertation on the X-ray
crystallography of hemoglobin when Watson arrived, eager to recruit a colleague
for work on DNA. Inspired by Pauling’s success in working with molecular
models, Watson and Crick rapidly put together several models of DNA and
attempted to incorporate all the evidence they could gather. Franklin’s
excellent X-ray photographs, to which they had gained access without her
permission, were critical to the correct solution. The four scientists
announced the structure of DNA in articles that appeared together in the same
issue of Nature.
Separate
Career Paths
Then
they moved off in different directions. Franklin went to Birkbeck College,
London, to work in J. D. Bernal’s laboratory, a much more congenial setting for
her than King’s College. Before her untimely death from cancer she made
important contributions to the X-ray crystallographic analysis of the structure
of the tobacco mosaic virus, a landmark in the field. By the end of her life
she had become friends with Francis Crick and his wife and had moved her
laboratory to Cambridge, where she undertook dangerous work on the poliovirus.
Wilkins applied X-ray techniques to the structural determination of nerve cell
membranes and of ribonucleic acid (RNA)—a molecule that is associated with
chemical synthesis in the living cell—while rising in rank and responsibility
at King’s College. Watson’s subsequent career eventually took him to the Cold
Spring Harbor Laboratory (CSHL) of Quantitative Biology on Long Island, New
York, where as director from 1968 onward he led it to new heights as a center
of research in molecular biology. From 1988 to 1992 he headed the National
Center for Human Genome Research at the National Institutes of Health.
Afterward he returned to CSHL, from which he retired in 2007. During Crick’s
long tenure at Cambridge, he made fundamental contributions to unlocking the
genetic code. He and Sydney Brenner demonstrated that each group of three
adjacent bases on a single DNA strand codes for one specific amino acid. He
also correctly hypothesized the existence of “transfer” RNA, which mediates
between “messenger” RNA and amino acids. After 20 years at Cambridge, with
several visiting professorships in the United States, Crick joined the Salk
Institute for Biological Studies in La Jolla, California.
Further Recognition
In
2005 James Watson was honored with the Othmer Gold Medal from
the Chemical Heritage Foundation, now the Science History Institute, for his
scientific talent, which has given the world a new intellectual understanding
of the nature of life, making possible modern biotechnology and a better life
for all mankind.
The information contained in this biography was last updated on December
4, 2017
With affection,
Ruben.
