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round transparent blobs

Thermal proteins seen through a microscope

Around four billion years ago, some of the amino acid molecules that were on the planet Earth began to join together into bigger molecules with hundreds of atoms in them, called themal proteins. Probably this happened in places where the water in the oceans on Earth was heated up by underwater volcanoes, because heating amino acids is what makes them join together into proteinoids.

Thermal proteins are chains of amino acid molecules all stuck together. They’re not exactly one big molecule, but a bunch of individual molecules stuck together through a different kind of chemical bond. Instead of forming a solid clump, thermal proteins form a hollow sphere of molecules, with a space inside it (It looks like a circle in the picture because you are looking down at it from the top).

This is because some of the amino acids in the thermal protein chemically don’t like water (just the way oil tries to get away from water), and so they make a ball, all trying to get as far away from the water as they can.They can’t help doing that; it’s automatic. The whole thermal protein is about ten to fifteen microns in diameter, about the size of a small living cell (and much too small to see).

thermal proteins budding: three circles connected by little bridges

Thermal proteins making new thermal proteins through budding

Thermal proteins could do a lot of the same things that living cells do today. They could divide in half to make more thermal proteins like themselves, as these thermal proteins in the picture are doing. They could let some molecules pass through their wall, while keeping other molecules out (osmosis).

In many ways, thermal proteins were a lot like living cells, but they were not alive. In order to become alive, the thermal proteins had to combine with RNA or DNA to make living cells.

Learn by Doing – An experiment with oil and water
The next step to living things: cells

Bibliography and further reading about proteinoids:

Parts of a Cell
Biology Home