Race to Solve the Mystery:
together at the University of Cambridge in England, James Watson,
an American scientist, and Francis Crick, a British researcher,
made a major scientific breakthrough when they discovered the
helix" -- the structure of DNA, the molecule of life.
the April 25, 1953, issue of the science journal Nature, Watson
and Crick wrote: ""We wish to suggest a structure for the salt
of deoxyribose nucleic acid (DNA). This structure has novel features
which are of considerable biological interest."
modest words were an understatement. Nine years later,
in 1962, they received the Nobel Prize for answering one of science's
long-pondered mysteries, advancing the emerging field of molecular biology
in the process.
and Crick's quest helps illustrate how collaboration,
creativity, hard work, and serendipity often conspire on the
path to scientific achievement.
A Eureka Moment
acid (DNA) was first isolated in
1869 by the Swiss scientist Friedrich Miescher. He called the
white, slightly acidic chemical that he found in cells
"nuclein." By the late 1940s, scientists knew what
DNA contained -- phosphate, sugar, and four nitrogen-containing
adenine (A), thymine (T), guanine (G), and cytosine (C). But
no one had figured out what the DNA molecule looked like.
1953, Linus Pauling, the great American chemist, claimed to
have discovered the structure of the DNA molecule, but when Watson
saw Pauling's research paper (which had not yet been published)
on January 28, 1953, he knew it was wrong. A few days later at
King's College in London, Watson was shown an X-ray diffraction
photograph (see left) of
the DNA crystal taken by scientist Rosalind Franklin.
"The instant I saw the picture, my mouth fell open and my pulse began to race," wrote Watson in his book The Double Helix (1968). The photo convinced him that the DNA molecule must consist of two chains arranged in a paired
helix, which resembles a spiral staircase or ladder.
DNA molecule resembles a spiral staircase or ladder. The
sides of the ladder are made up of alternating molecules
of phosphate and the sugar deoxyribose, while each rung is
composed of a pair of nitrogen-containing chemical bases
connected in the middle. DNA has four bases - Adenine, Thymine,
Cytosine, and Guanine. These bases always join up with the
same partners - A with T, and C with G. Graphic courtesy
Craig Venter Institute.
and Crick set about developing a stick-and-ball model of DNA's
possible structure. The sides of the ladder were made up of alternating
molecules of phosphate and the sugar deoxyribose, while each
rung on the ladder was composed of a pair of nitrogen-containing
bases connected in the middle.
At first, the scientists were uncertain how DNA's four bases -- A, T, C, and
G -- link up with each other. Then thanks to a suggestion from
a colleague, they realized that the bases always join up with
the same partners - A with T, and C with G.
March 7, 1953, Watson and Crick finished their model, which reached
6 feet tall. "A Structure for Deoxyribose Nucleic Acid" was
published in Nature on April 25, 1953.
By the late 1950s, their work had been widely accepted by the
1962, Watson and Crick received the Nobel Prize for Physiology
or Medicine with Maurice Wilkins. He had published important
crystallography work relating to DNA at the same time as Watson
and Crick. Rosalind Franklin, whose photograph provided "a Eureka
moment" for Watson,
died in 1958 of cancer. Scientists wonder if she would have been
honored with the award as well, had she lived.
their discovery, Watson and Crick stayed in touch, but took different
paths in science. Watson joined the faculty of Harvard University
in 1955, focusing his research on the role of ribonucleic acid
(RNA) in protein synthesis. In 1968, he became director of Cold
Spring Harbor Laboratory on Long Island, New York. It conducts
research on cancer, plant molecular biology, cell biochemistry,
and neuroscience. In 1989, he was appointed director of the National
Center for Human Genome Research at the National Institutes of
Health and launched a worldwide effort to map and sequence the
human genome. In 1994, he became president of Cold Spring Harbor
was made a Fellow of the Royal Society in England in 1959. Working
with Sydney Brenner, he sought to "unravel the genetic
by determining how the sequence of DNA bases would specify
the amino acid sequence in proteins. By 1961, they had shown
that this translation involves a three-nucleotide code, or codon,
which opened the door to new biotechnology research ranging from
genetic fingerprinting to screening for inherited diseases. In
1976, Crick joined the Salk Institute for Biological Studies
in San Diego, California, where he became
involved in studies of neurons and how the brain functions.
He served the institute as both a distinguished research scientist
and former president. Crick died on July 28, 2004, at the age
Nobel Prize: http://nobelprize.org/medicine/laureates/1962/index.html
a Genome: http://www.genomenewsnetwork.org/resources/whats_a_genome/Chp1_1_1.shtml
Science Photo Library: http://www.sciencephotogallery.co.uk/articles/DNA_50yearsArticle.php
Biography of James Watson: http://www.cshl.org/public/SCIENCE/Watson.html
Biography of Francis Crick: http://www.wellcome.ac.uk/en/genome/geneticsandsociety/hg13b001.html