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MILLER

Stanley Miller 1930-2007

 Automatic translationAutomatic translation Category: biography
Updated June 01, 2013

Stanley Lloyd Miller was born March 7, 1930 in Oakland, California. It is an American biologist considered the father of the chemistry of the origins of life on Earth, largely thanks to the famous experiment, called the Miller-Urey Experiment.
At the age of 23 years working as a researcher Stanley Miller at the University of Chicago when he realizes in 1953, experience that made him famous.
This experience allows him to quickly publish his doctoral thesis in 1954.
He became known for his experimental work on the origins of life and recreating in the laboratory the conditions of the primordial soup. Stanley Miller has published more than sixty scientific papers.
In the early 1950s, he worked in the laboratory of Professor Harold Urey, Nobel Prize in Chemistry in 1934 for the discovery of heavy hydrogen, deuterium. Early in his studies, Stanley Miller is interested in the primitive chemistry that is at the origin of life on Earth.
He tries to create conditions which would enable the emergence of the first molecules in a prebiotic Earth. Harold Urey was convinced that existed on early Earth atmosphere containing the necessary chemical structures of living things.
In 1953, to check the relevance of this theory, imagine a Stanley Miller experiment physicochemical. The apparatus is filled with an atmosphere of methane, ammonia and hydrogen.
A water balloon simulates a primitive ocean (the water is heated by a resistance, which contributes to enriching the atmosphere with water vapor).
Two electrodes, which are used to produce lightning, provide energy to the system.

 

After a week of operation, various organic compounds including amino acids 2% primitive rush to the bottom of the flask. Amino acids are the basis of all links in the protein chains that exist on Earth.
These results were confirmed later by other experiments but in the meantime, the concept of original soup of life, a great success.
Almost immediately the amount of critical conditions of the experiment. Miller and Urey used a reducing atmosphere rich in hydrogen (CH4, NH3, H2, H2O) and not an oxidizing atmosphere.
The primitive atmosphere rather prefer a non-reducing atmosphere, composed mainly of CO2, or the experience of Stanley Miller does not work in this type of atmosphere. Under reductive atmosphere (carbon dioxide CO2, N2, H2O) that comes from volcanic gives very poor yields. But Miller's experiment is an interesting step in the gradual evolution towards complexity.
He placed in front of the stage, organic chemistry in water and has a large number of experiments have exploited this vein.
Today, many models are created to solve the problem of the appearance of organic molecules. Scientists are able to produce many small organic molecules (amino acids, sugars, nucleic bases) in pre-biotic conditions in laboratories. Miller experiments and models derived provide no explanation of the steps that ultimately lead to living cells.
Stanley Lloyd Miller died of a heart attack, May 20, 2007 without ever having received the Nobel Prize.

 Stanley Miller

Image: Stanley Lloyd Miller Nobel Prize in Chemistry in 1934 for the discovery of heavy hydrogen, deuterium. Noncommercial, educational use only.

Life is no longer a privilege landowner

    

Life is perhaps more privileged landowner. In 1865, German Hermann Richter believes that we erred in seeking the origins of life on our planet.
Life could come from the depths of space and Earth would easily have been seeded with particles of heavenly beings swarming the cosmozoaires.
Buried in the heart of meteorites, they could cross the Earth's atmosphere without damage. This theory is considered seriously by most scientists.
This theory, which states that life comes from the cosmos, is known as panspermia.
As attractive as it is, panspermia does, however, that push the mystery of the origins of life, moving from Earth to space.
If life is born at the same time that the universe has always existed and that this explains its presence on Earth, without solving the problem of its occurrence in the Universe.
However the synthesis of organic molecules appears to be very common in space.
In the interstellar void, scientists have identified some 120 organic molecules containing between 2 to 13 carbon atoms.
Many alien bodies, comets and meteorites also contain a variety of organic molecules of varying complexity.

 

The man now asks the universal nature of the couple carbon / water. This combination has resulted in the formation of living beings, is certainly not the only one that nature has at its disposal.
Ammonia, consisting of a nitrogen atom connected to three atoms of hydrogen (NH3), has physical properties similar to that of water but unlike the latter, the ammonia is liquid between -78 ° C to -33 ° C.
Chemical reactions can take place in this solvent are much slower than those taking place in water (reaction rates decrease with temperature).
Following a similar reasoning, the exobiologists have speculated on the existence of life forms built not on carbon but on an atom with similar properties, silicon just below carbon in the periodic table of Mendeleev, silicon is also tetravalent (i.e. it can form four bonds with other atoms, like carbon).
But these bonds are too strong and require too much energy to be broken and thus allow the many reactions essential to life.
The universe does not seem to have fun with silicon.

 The experience of Stanley Miller

Image: The experience of Stanley Miller.
The apparatus is filled with an atmosphere of methane, ammonia and hydrogen. A water balloon simulates a primitive ocean (the water is heated by a resistance, which contributes to enriching the atmosphere with water vapor). Two electrodes, which are used to produce lightning, provide energy to the system. After a week of operation, various organic compounds including amino acids precipitate at the bottom of the ball.

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