About 100 years ago F. Engels defined life as the “mode of motion of a albuminous substances”. Modern sciences succeeded in tracing the stages of the evolution of life from a barren, entirely inorganic earth through the formation of organic compounds, their polymerization to giant-chained molecules of proteins and nucleic acids, the formation of living cells and the whole process of Darwinian evolution to man.
Polymeric compounds are chemical substances composed of the same elements in the same proportion but with different molecular weights. They are liquid or gaseous substances with small molecules (C2H2 — acetylene, C6H6— benzine).
Scientists have found ways of joining the small molecules together into long chains thus forming a solid with various properties of polythene or other plastic.
A similar process of the formation of long-chain molecules from small ones goes on in living cells. Proteins and ammo-acids are the building bricks of the living matter. Living organisms produce proteins from the food they absorb.
There are several hundred proteins. They are made from about 20 simpler molecules called the amino-acids. The amino-acids are joined nose to tail as are the molecules in polythene. But the structure of the chains in proteins is much more complicated than in polythene. Each type of protein is made of a precise number of each kind of amino-acid. There is even precise order in which each simple molecule joins the chain. Chemists are unable to produce such polymers yet.
Still we are getting some insight into the structure of natural polymers. We are beginning to understand the structure of chromosomes — thread-like parts of the cell dictating the order in which the various smaller molecules join together to make the long-chain nucleic acids RNA and DNA. RNA and DNA carry the genetic code which plays a big role in the process of heredity. We can’t yet answer the question when life began. It must have started with the development of self-replicating polymers.