BBC Science The Theory of (nearly) Everything 2019

(Martin Jones) #1
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WILLIAM ASTBURY
(1898-1961) was a
British molecular
biologist and physicist
who spent much
of his working life
in Leeds. His work
focused originally
on the structure of
proteins in textiles but,
along with his PhD
student Florence Bell,
he took the first X-ray
photographs of DNA
in 1937.

FRANCIS CRICK
(1916-2004) was born
near Northampton to
the owner of a shoe
factory and became a
British biophysicist and
molecular biologist.
After co-discovering
the structure of DNA,
he went on to
determine how DNA
codes for proteins,
before venturing
into neuroscience.

JAMES WATSON
(1928-) is an
American geneticist
and molecular
biologist born in
Chicago, who gained
his PhD at just 22. After
co-discovering DNA’s
structure in Cambridge
in 1953, he worked at
Harvard University and
then the Cold Spring
Harbor Laboratory
until he retired in 2007.

ROSALIND FRANKLIN
(1920-1958) was born
in London to a rich
Jewish family. The
X-ray crystallographer
and biophysicist
provided much of the
experimental evidence
for the structure of
DNA before switching
her focus to viruses.
She died of cancer
at the age of 37.

MAURICE WILKINS
(1916-2004) was a
British physicist and
molecular biologist
who was born in New
Zealand. As well as
his DNA research,
he worked in fields
such as radar and
microscopy. He
remained at King’s
College until his
retirement in 1981.

5 so reinforced the idea that proteins
must be t he heredita r y agent.
Revealing DNA’s hidden complexity
was going to require a closer look.
While Levene was unravelling the
complexities of DNA in New York,
across the Atlantic a father-and-son
team was establishing a technique
that would prove crucial to
determining DNA’s structure.
William Henry Bragg, a physicist at
the University of Leeds, and his son
William Lawrence Bragg, a researcher
at the Cavendish Laboratory in
Cambridge, laid the foundations for
the field of X-ray crystallography
between 1912 and 1914. They were
inspired by the work of Max von
Laue, who discovered in 1912 that
X-rays bend when they pass through
crystals, substances with highly
ordered structures.
The younger Bragg reasoned that,
because they have ordered patterns of
atoms, the way that the X-rays bend
through crystals would reveal
something about their structure. His
more practically minded fat her built
the first X-ray spectrometer – a device
for shooting a narrow beam of X-rays at
substances – and together they tested
the theory on salt crystals.

Bragg’s Law
In these experiments, the Braggs
placed a photographic plate behind
the crystal, onto which the scattered
X-rays would produce a characteristic
pattern. William Lawrence Bragg
ca me up wit h a n equation, k now n
as Bragg’s Law, that allowed them to
work backwards from the patterns to
deduce the crystal’s structure. The
pair won a Nobel Prize in 1915.
One of the first groups to apply this
technique to biological molecules was
headed by William Astbury, who
began working at the University of
Leeds in 1928, having studied under
William Henry Bragg at the Royal
Institution. In 1937, Astbury was sent
samples of calf DNA by Swedish
researcher Torbjörn Caspersson. A few
years previously, Caspersson had
shown that DNA is a polymer – a long
chain of nucleotides – rather than the
short lengths Levene had suggested.

It took the efforts of these science greats to
finally realise the structure of DNA

CAST OF CHARACTERS


THE FUNDAMENTALS OF LIFE

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