Formation of Polymers

You just learned about the formation of monomers. When monomers are joined together, they form polymers. Normally this occurs with enzymes, but 3.8 billion years ago, enzymes probably did not exist. To make it even more interesting, how can dilute monomers be concentrated so they could even possibly join together?

There are currently three hypotheses to explain how dilute monomers are brought together. The first hypothesis is that water containing monomers is splashed onto hot rocks and as the water evaporates, the monomers are slowly concentrated, especially if water with monomers is continuously added to the evaporating pool. Dr. Fox tested this hypothesis by dripping water with monomers onto heated lava rocks. When he analyzed the concentrate he found polypeptides. He called these abiotically formed polypeptides proteinoids. Add a little wave action and the polymers can be added to the sea. Since then other scientists created polypeptides by splashing dilute solutions onto hot sand and clay as well.

The second hypothesis is that clay particles played an important role in bringing monomers together. Clay particles are electrically charged as are monomers. Clay particles can concentrate monomers from a dilute solution. If the clay particle contains metals like zinc and iron, these metals catalyze the reaction to combine monomers into polymers. And the clay does not even have to be warm!

The third hypothesis is that fool's gold, or iron pyrite, may have catalyzed the formation of polymers. Iron pyrite, made up of iron and sulfur, provides a charged surface to attract monomers and the reaction between iron and sulfur could provide electrons to help bind organic molecules together.

• Of these three hypotheses, which one do you think has the most credibility in describing the early abiotic formation of organic molecules?
• Now that we have hypotheses for describing how organic polymers are formed, how do these polymers aggregate and interact to form higher levels of order?

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