Miller-Urey Experiment — Setup and Significance — Notes | NoteTube

Cue Column | Notes Column

What gases? | CH4 (methane) + NH3 (ammonia) + H2 (hydrogen) + H2O (water vapour). No free O2.

Energy source? | Electric sparks = simulated lightning.

Apparatus? | Closed glass system with a boiling flask (simulating ocean) connected to a discharge chamber.

Result after 1 week? | Amino acids (glycine, alanine) and other organic molecules accumulated in the condenser/trap.

Year and scientists? | 1953, Stanley Miller and Harold Urey.

What did it prove? | Amino acids can form abiogenically under conditions resembling early Earth's reducing atmosphere — supporting Oparin-Haldane hypothesis.

Why no O2? | Free oxygen would oxidize (destroy) organic molecules as they formed. Early Earth's atmosphere was reducing, not oxidizing.

Miller-Urey Apparatus Wikimedia Commons: Miller-Urey experimental apparatus diagram

Summary Box

Miller-Urey (1953) = CH4 + NH3 + H2 + H2O + electric spark (no O2) → amino acids. This is experimental support for abiogenic origin of organic molecules, not proof of life itself.

NEET Trap

Students confuse Miller-Urey (amino acid synthesis) with Griffith (transformation in bacteria) or Hershey-Chase (DNA as genetic material). Each experiment belongs to a completely different topic.