Melvin Calvin
Born 8 Apr 1911; died 8 Jan 1997
Melvin Calvin was born in St. Paul, Minnesota, USA. His parents were
Russian immigrants. He went straight from his first science degree to
a doctorate and then on to a career in scientific research. He began
his most famous work on photosynthesis at the end of the Second World
War. The story is that on the day the Japanese surrendered after the
dropping of the two atom bombs, Earnest Lawrence told the 34 year old
Calvin that it was 'time to do something useful' with all the radioactive
carbon-14 he had discovered how to make during the war years. Calvin
set up a team of young scientists - at 34 he was about the oldest -
and for the first time he got together biologists, chemists and physicists
who all worked together contributing different skills to the research.
Calvin decided to use carbon-14 isotope as a tracer in the reactions
of photosynthesis. It was a very difficult process, because the reactions
had to be carried out in living cells. The radioactive tracer in the
form of labelled carbon dioxide was given to the plants for a brief
time. The plant cells were then killed at various intervals after the
labelled gas was given and the labelled chemicals identified. It took
years, but eventually Calvin and his team mapped the complete route
that carbon travels through a plant during photosynthesis, starting
from its absorption as atmospheric carbon dioxide to its conversion
into carbohydrates and other organic compounds. The sequence of reactions
are called the Calvin Cycle.
The Calvin group showed that sunlight acts on the chlorophyll in a
plant to fuel the manufacturing of organic compounds, rather than on
carbon dioxide as was previously believed. They also demonstrated the
"dark reactions" of photosynthesis which occur through the
night turning carbon dioxide into sugar. Melvin Calvin won 1961 Nobel
Prize for Chemistry for his discovery of the chemical pathways of photosynthesis.
Charles Bonnet
Joseph Priestley
The Photosynthesis Story
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