CBSE · Class 12 · Biology · EvolutionDescribe the Miller-Urey Experiment. How did its observations support the theory of chemical evolution of life?

Miller-Urey Experiment

\nIn 1953, Stanley Miller and Harold Urey provided experimental proof for the Oparin-Haldane hypothesis of chemical evolution, which proposed that life originated abiotically from non-living organic molecules under reducing primitive atmospheric conditions.

Experimental Setup:

1. Apparatus: They created primitive Earth conditions in a sealed spark flask apparatus containing gases like Methane ($CH_4$), Ammonia ($NH_3$), Hydrogen ($H_2$), and Water Vapor ($H_2O$).
2. Energy Source: High-voltage electric sparks ($7500-10000\text{ V}$) were discharged using tungsten electrodes at $800^\circ\text{C}$ to simulate natural lightning.
3. Condenser: A liquid condenser was attached to cool down the gas mixture and collect condensed liquid products.

Observations and Conclusion:\nAfter running the apparatus for a week, the chemical analysis revealed the synthesis of simple organic molecules, including amino acids (such as glycine, alanine, and aspartic acid), organic acids, and sugars. This proved that essential biological macromolecules could form spontaneously from inorganic gases under pre-biotic Earth conditions.