Origin of life – Miller–Urey experiment, spontaneous generation and protocells
BiologyEvolutionAges 17–18Virtual lab
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Four screens on the origin of life. Spontaneous generation: repeat Redi's meat jars, Needham's and Spallanzani's boiled broths and Pasteur's swan-neck flasks to see that living things come only from living things. Miller–Urey: choose the gas mixture (CH₄, NH₃, H₂, H₂O or a CO₂/N₂ atmosphere), the spark energy and the run time, then read the yields of glycine, alanine and other amino acids in a table and on a paper chromatogram. Hypotheses: the early Earth at four times, with Oparin–Haldane's primordial soup, hydrothermal vents, warm little ponds and material from space. Protocells: fatty acids assembling into vesicles, a ribozyme copying RNA, and the features all life shares from LUCA.
Lesson: Origin of life: chemical evolution, prebiotic evolution, spontaneous generation and biogenesis
What it shows
How did life begin? Experiments by Redi, Spallanzani and Pasteur showed that maggots and microbes do not arise from non-living matter, so living things come from living things. Oparin and Haldane proposed that the first life formed through chemical evolution: simple molecules in the early atmosphere, given energy from lightning and ultraviolet light, formed organic compounds. In 1953 Miller and Urey made amino acids this way in the lab. Other hypotheses place the start at hydrothermal vents, in warm ponds or on material from space; fatty acid vesicles and self-copying RNA suggest how the first protocells could have formed.
How to use
Choose a screen with the tabs. Miller–Urey: pick the Gas mixture, Spark energy and Run time, press Run, then compare the runs in the table. Spontaneous generation: choose an Experiment and press Run; with Pasteur, try Tilt flask 1. Hypotheses: tap the numbers on the picture and change the Time. Protocells: choose Fatty acid vesicles, RNA world or LUCA.
Parameters you can change
- Screen Spontaneous generation?, Miller–Urey, Hypotheses, Protocells
- Experiment Redi (1668): meat jars, Needham and Spallanzani (1748, 1768): broth, Pasteur (1859–1862): swan-neck flasks
- Gas mixture CH₄ + NH₃ + H₂ + H₂O (Miller 1953), CO₂ + N₂ + H₂ + H₂O, CO₂ + N₂ + H₂O, CH₄ + H₂ + H₂O (no nitrogen)
- Spark energy (compared with Miller's) 0–200 %
- Run time 1–14 days
- Time 4.5 billion years ago, 4.0 billion years ago, 3.5 billion years ago, 2.4 billion years ago
- Part Fatty acid vesicles, RNA world, LUCA
- Fatty acid concentration 0–4 × CVC
- Montmorillonite clay
- Sea water (much Mg²⁺, Ca²⁺)
- Error rate per nucleotide 0.1–10 %
- RNA length 20–200 nt
Questions to explore
- Why did Pasteur's swan-neck flask stay clear even though air could reach the broth?
- Why does Miller's mixture give far more amino acids than CO₂, N₂ and water?
- Why does copying fail when each copy has, on average, more than one error?
