By: Ivy Philips
Erwin Chargaff’s most notable discovery was finding out through
experimentation was that in DNA, Adenine bonds with Thymine, and Cytosine bonds
with Guanine. He discovered this because in DNA the amount of units for each one
was equal to the other (A=T, C=G) This proved his theory and debunked the commonly
accepted Tetranucleotide Hypothesis. This hypothesis stated that DNA was made of a
random reoccurrence of GATC. Chargaff’s Rules also said that the amount of base
pairs varied for different organisms. He stated that genetic material was carried by
DNA and not by nucleic acids, as had been previously thought. This was a
revolutionary breakthrough in science because he opened up new levels of science
nobody had ever thought to study before. This theory introduced the idea genetic
diversity. In 1952 Chargaff introduced his ideas to Francis Crick and James Watson.
These scientists took Chargaff’s idea and built a model off of it. This model is called
the Double Helix which was meant to display the way DNA is formed, and how the
base pairs connect. Chargaff’s research and experiments forever changed the way
scientists study and look at heredity and biology.
Francis Crick was a scientist from London, England. He worked on different project
involving x-ray diffraction, biochemistry, chemistry, and physics. He was skilled in all of
these subjects, but he most enjoyed the mysteries of genetic material and DNA. He was
working at Cavendish Laboratory at Cambridge. In that lab he and his colleges were
studying the structure of proteins using x-ray diffraction. While doing the lab he met
James Watson. He and Watson established a great relationship in the lab. They both
were interested in the same mysteries posed by DNA and genetics. Crick understood
that should scientists know more about DNA, a model of some sorts must be
established. This led his and Watson’s work on the double helix. They used x-ray
diffraction to see the actual DNA and actual evidence from other scientists about base
pairs and formed a reliable model. This model is know widely around the world and it is
the most dependable model. Crick and Watson won the Nobel Prize in
physiology/medicine in 1962. Even after his breakthrough findings and imminent
success, he still continued to study genetics and how genetic material is coded
throughout cells.
James Watson is a molecular biologist, geneticist, and zoologist. He is most
famous for his work with Francis Crick on the DNA double helix model. Before he
met Crick, though, he was working with the Phage Group. The Phage Group was a
group of scientists led by Max Delbruck and Salvador Luria. This group conducted
experiments on bacteriophages. Watson’s involvement in the Phage Group
jumpstarted his interests in the structure of DNA. He later broke away from the
Phage Group and began working with other scientists, but he frequently used
Phages in his studies. In 1953 James Watson began doing research at the
Cavendish Laboratory at Cambridge University. This is where he met Francis Crick.
Francis was interested in the same things he was, so a close relationship was
formed. They were both curious as to the shape of DNA and both believed that it
could be reviled through x-ray diffraction. They made a model of DNA using a
double helix. There findings were published and they later received a Nobel Prize
in Physiology and Medicine. He continued working in science for a very long time.
In 1990 he was appointed head of the Human Genome Project. He remained in
this position for two years until he resigned in 1992 to work on another project.
Hermann Muller was an American geneticist. He is most famous for his work
involving radioactive material and genes. 1926 marked an incredible
breakthrough in genetics and for Muller. Muller made a series of experiments
involving various amounts of x-rays and genes. In his research and
experiments there was a clear and defined connection between radiation
and deadly mutations. These findings unnerved the science community
because no findings of this nature had ever occurred before. After his
discovery people started to be a bit more cautious of what wastes they put
out and how radioactive material was handled. Muller was a very outspoken
activist for the elimination of nuclear war and nuclear testing. In 1946 he was
awarded the Nobel Prize in Physiology and Medicine for his discovery that
mutations can be induced by radioactivity. After the world saw the effects
the nuclear bombs had on Hiroshima and Nagasaki, they all listened to
Muller. Today many precautions are made when it comes to nuclear testing
and radioactive materials because of Hermann Muller’s findings.
Barbara McClintock is one of the world’s most renown cytogeneticists. A
cytogeneticist is a person that studies the structure and function of a
cell. In cytogenetics, chromosomes are thoroughly studied, too.
McClintock started her career studying maize, which is a type of corn.
Her main focus was to study the way maize cells reproduce. This allowed
people to see how chromosomes changed inside the cell using
microscopes. She discovered that in corn there are transposable
elements. For years people had thought of DNA and chromosomes as
‘junk elements’. Barbara proved them all wring with her research on
maize. Throughout her lengthy career she has been awarded numerous
medals and honors for her work. In 1983 she was awarded the Nobel
Prize in Physiology or Medicine.
1926
Hermann Muller
Mid 1940s
Chargaff’s rules
1940s
Barbara
McClintock
Early 1950s
James Watson
Early 1950s
Francis Crick
*Note: All of these scientists continued there work for a long time, so it is hard
to place their years of ‘most activity’ on a time line. This is when they began to
get recognition for their ideas/work or published them.