Miller - Urey Experiments
In 1953, two scientists, Stanley Miller and his tutor Harold Urey, working for the University of Chicago, recreated the hypothetical conditions of early earth, in order to attempt the formation of organic compounds. The pair worked using the hypothesis of two earlier scientists. Oparin and Haldane suggested that under the strongly reducing conditions theorised to have been present in the atmosphere of the early earth (between 4.0 and 3.5 billion years ago), inorganic molecules would spontaneously form organic molecules (simple sugars and amino acids). Miller and Urey tested this hypothesis, and so became the Miller-Urey experiment.
1. The Experiment
To test whether it was possible for complex organic molecules could be formed through slow spontaneous reactions, Urey and Miller needed to simulate hypothetical conditions of primitive Earth. To represent the atmosphere Urey and Miller used the chemicals methane (CH4), ammonia (NH3), hydrogen (H2) and water (H2O). This combination was sealed in sterile flasks, with the water in a separate flask in liquid form. The flasks were looped together and one flask contained a pair of electrodes to create a similar form of energy to lightening. The water was heated to induce evaporation, sparks were fired through the ‘atmosphere’ and water vapor to simulate lightening, and then to condense the water the atmosphere was cooled so that it would trickle back into the first flask, and the cycle would rebegin.
The tests were carried on for one week until the end where they were taken up from the collection trap for laboratory testing and analysis. The results showed that 4% of the carbon, once chemically bonded to form methane, had now formed amino acids. In this experiment and the successive ones, it was found that the twenty amino acids that are commonly found in organisms could be created. These compounds included nucleic acids, sugars, lipids and adenine, and it was also possible for ATP to be...