The forming of complex organic molecules, or polymers, from simpler building-block molecules may have been inevitable on the primitive Earth. H and OH groups are removed from the monomers. H2O is produced as a by-product. Dilute solutions of organic monomers are dripped onto hot sand, clay, or rock. Water vaporizes and concentrates the monomers on the substrate.
Monomers bind to charged sites in clay, concentrating amino acids and other monomers.
The binding sites on clay could have brought many monomers close together and assisted in forming polymers. It has a charged surface and electrons freed during its formation could support bonding between molecules. D. Protobionts can form by self-assembly Living cells may have been preceded by protobionts. Aggregates of abiotically produced molecules able to maintain an internal environment different from their surroundings and exhibiting some life properties such as metabolism and excitability. When mixed with cool water, proteinoids self-assemble into microspheres surrounded by a selectively permeable protein membrane.