Born on July 25,
1920 in London, England, Rosalind Elise Franklin was a catalyst to
many other scientists in the field of genetics. Using coal and carbon
as subjects, Franklin discovered the double helix of DNA, the shape
that two linear strands of DNA assume when bonded together. In 1945,
Franklin received her Ph. D in physical chemistry from Cambridge
University. The next year she went to Paris and worked in the
Laboratoire Central des Services Chimiques de L?Etat until 1950 where
she concentrated her studies on x-ray diffraction methods.
Franklin returned to England to work as an associate to John Randall
at King?s College. While Maurice Wilkins, a scientist, was away,
Franklin was put in charge of his DNA project. Wilkins returned to
think that Franklin was a lowly technical assistant mainly because of
the discrimination against women at that time. During her studies,
Franklin took pictures of the DNA structure using her own technique
discovering a helical structure. Through this technique, Franklin
discovered that there were two types of DNA, dry A-form and wet
b-form. B-form being the DNA that exist within our bodies. She also
located the position of phosphate sugars in DNA. With this technique,
the locations of atoms can be precisely mapped by looking at the
crystal under an x-ray beam.
How X-Rays work
unlike with visible light, there is no known way to focus x-rays with
a lens. This causes an x-ray microscope to be impossible to use
unless someone finds a way of focusing x-rays. So it is necessary to
use crystals to diffract x-rays and create a diffraction pattern.
Crystals are important because by definition they have a repeated
unit cell within them. The x-ray diffraction from one unit cell would
not be significant. Fortunately, the repetition of unit cells within
a crystal amplifies the diffraction enough to give results that can
turn into a picture.
To perform x-ray
crystallography, it is necessary to grow crystals with edges around
0.1-0.3 mm. Crystals are formed as the conditions in a supersaturated
solution slowly change. There are three degrees of saturation in
solution, and crystallographers take advantage of these when growing
? Unsaturated –
where no crystals will form or grow.
supersaturated – where crystals will grow but no new ones will
supersaturated – where crystals will both form and grow.
Back to her life
Between 1951 and
1953, Franklin came close to discovering the structure of DNA but was
sabotaged by James Watson and Francis Crick, an American Biochemist
and British Biochemist, respectively. Without Franklin?s knowledge or
permission, the two published all her information and some of her
pictures. Among these pictures was one of Franklin?s crystallographic
photos of DNA. She later published the same information in a science
journal and published five other articles. Four years after her death
Crick and Francis were awarded the Nobel Prize for the Double Helix
model of DNA. During this time in the laboratory, Franklin produced
clear pictures of the helix that are still used in textbooks today.
In the spring of
1953, Franklin moved to J.D Beroznal?s laboratory at Birbeck College.
She worked on the tobacco mosaic virus and the polio virus. During
this time she was asked to speak at many conferences around the world
and published 17 papers in five years. Her research laid a foundation
for structural virology.
In the summer of
1956, Franklin became sick and was diagnosed by an American doctor
with ovarian cancer. She continued work over the next two years
through three operations, experimental chemotherapy and a 10-month
remission. She worked up to a few weeks before her death on April 16,
1958 in London at age 37.
After her death,
Anne Sayre, a friend, wrote the book Rosalind Franklin and DNA that
told the real story of Franklin?s role in DNA research. This book was
published in 1975. Because of this book, Franklin finally received
recognition for her discoveries.
Sir Aaron Klug,
1982 Nobel Laureate in Chemistry stated that ?Rosalind Franklin made
crucial contributions to the solution of the structure of DNA. She
discovered the B form, recognized that two states of the DNA molecule
existed and defined conditions for the transition. From early on, she
realized that any correct model must have the phosphate groups on the
outside of the molecule. She laid the basis for the quantitative
study of the diffraction patterns, and after the formation of the
Watson – Crick model she demonstrated that a double helix was
consistent with the X-ray patterns of both the A and B forms.? Sir
Aaron Klug is known for his development of crystallographic electron
microscopy and his structural elucidation of biologically important
nuclei acid-protein complexes.