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Primordial Soup

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Primordial Soup
Selfish RNA
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The Primordial Soup Theory

Amino acids forming Proteinoids

(Out of the Slime)


The Primordial Soup Theory states that  Life began in a warm pond/ocean from a combination of chemicals that forms amino acids, which then make proteins. This is suppose to happen at least 3.8 billion to 3.55 billion years ago.

The Russian Chemist A.I. Oparin and English Geneticist J.B.S. Haldane first conceived of this idea. Both developed this theory independently in 1920.

In this theory, the basic building blocks of life came from simple molecule which formed in the atmosphere (w/o oxygen). This was then energized by lightning and the rain from the atmosphere created the "organic soup". The first organisms would have to be simple heterotrophs in order to survive by consuming other organisms for energy before means of photosynthesis. They would become autotrophs by mutation. Evidence now suggest the first organisms were autotrophs

Chemist Stanley Miller and physicist Harold Urey did a famous experiment in 1950 to test this theory. They mixed gases thought to be present on primitive earth:

Methane (CH4)

Ammonia (NH3)

Water (H2O)

Hydrogen (H2)

No Oxygen

 They then electrically sparked the mixture to signify lightning. The results were amino acids, the building blocks of proteins. It was later discovered that other energies also can excite gases and produce all 20 amino acids:


Ultraviolet light



Problems with theory

1.      Amino acids have to become protein

a.       1 protein = 100amino acids of 20 varieties

b.      10130 combinations of amino acids

c.       Hard to hit the right protein by accident

d.      Amino acids are building blocks, not the assembled structure

2.      Early atmosphere contain different gases than those used by Miller/Urey

a.       No ammonia and methane

b.      Not reduced (opposite of oxidized)

c.       Experiments with true atmospheric gases did not produce abundant amino acids

3.      2nd Law of Thermodynamics

a.       System becomes less and less organized over time

b.      Means amino acids cannot form protein spontaneously (more and more organized)

4.      Primordial soup too dilute to achieve anything

a.       Cannot spontaneously generate proteins

b.      No mechanism to concentrate and make protein


This theory emphasize metabolism because of the cooperative group of molecules and how they gain and use energy and molecules.

In an experiment by Sidney Fox, heated amino acids drove
out water as steam and made peptide chains. They were Proteinoids though, very different from real proteins.


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