In 1953, Stanley L Miller and Harold C. Urey of the University of Chicago conducted an experiment that is now considered to be the classic experiment concerning the origin of life. It simulated conditions (hypothetically) present on the primitive Earth and it proved the occurrence of chemical evolution. It was based on Oparin and Haldane’s hypothesis that chemical reactions that could synthesize organic compounds from inorganic components were favored on the early Earth.
In a nutshell, the experiment proved that amino acids could be created from exposing inorganic molecules to electricity. But it seems that this was not all to Miller’s experiments. Two other experiments, neither published, have been conducted. The vials containing products from those experiments have been recently recovered and they have been analyzed using today’s technology.
The new results, published in this week’s edition of Science, prove that the better experiment remained in the shadow for 55 years. The experiment that got Miller the Nobel prize was not the one that produced the wider variety of organic molecules. His second experiment was basically an upgrade of his first : an additional device was used to increase air flow trough an air-tight device.It seems that increasing the air flow works towards creating a better environment for chemical reactions.
The leader of the report, Adam Johnson stated : “The apparatus Stanley Miller paid the least attention to gave the most exciting results,”"We suspect part of the reason for this was that he did not have the analytical tools we have today, so he would have missed a lot.”
Due to the fact that identifiying organic compounds at that time was possible only if they were present in high levels, when Miller published his results in the May 15, 1953 edition of Science, he identified only 5 amino acids : two types of alanine,alpha-amino-butyric acid, glycine and aspartic acid. He later identified additional compounds like hidroxy and carboxylic acids. A team of chemists and biologists from the Scrips Institution of Oceanography, National Autonomous University of Mexico, Carnegie Institution of Washington and NASA Goddard Space Flight Center analyzed the vials from Miller’s experiments in the 1950’s, and the results were interesting at least. It seems that Miller’s initial experiment contained 14 amino acids, compared to only 5 that Miller thought. But his “upgraded” experiment, yielded22 amino acids and the same five amines present in the original experiment.
Jeffrey Bada, principal investigator for Science stated : “We believed there was more to be learned from Miller’s original experiment,” Bada said. “We found that in comparison to his design everyone is familiar with from textbooks, the volcanic apparatus produces a wider variety of compounds.” “Many of these other amino acids have hydroxyl groups attached to them, meaning they’d be more reactive and more likely to create totally new molecules, given enough time.”
Researchers believe that Miller opted to publish his simpler experiment given the fact that at the time the results seemed identical. But the air flow was removing new molecules from the spark before other reactions turned them into basic compounds again. ”
It seems scientists get closer and closer towards understanding how life arose on Earth.
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