From the Elements to Life
The Periodic Table of the Elements might seem like a surprising place to begin searching for clues to life’s origin, but this is exactly where some scientists begin.
Six Elements Form The Basis Of Life.
Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur
These elements have been present on Earth since its birth about 4.6 billion years ago. Bonding chemically in various combinations, they form the four kinds of molecules that constitute the building blocks of life—sugars, lipids, amino acids, and nucleobases.
But the Periodic Table contains close to 100 natural occurring elements. Life is not just a product of carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Biochemists have long known that trace amounts of Elements 21-30 also play crucial roles in living processes.
Origin of life researchers have noticed they these “transition metals,” which include iron, copper, and nickel, can attach themselves to small molecules (which then become known as “ligands”) and form catalysts for the synthesis of metabolites—essential parts in the network of components that constitute life. This has led some to scientists to hypothesize that transition metal ligand complexes could have served as catalysts in the earliest biochemical pathways.
An RNA World?
RNA is a key player not only in the transfer of genetic information, but also in the manufacture of enzymes, the complex molecules used by cells as catalysts today.
The discovery suggests to some that early in the history of life, RNA could have performed other crucial functions, including filling the role of catalysts themselves before there were enzymes.
This is part of the concept of an “RNA World” in which, among other things, RNA is the bridge between the hypothesized transition metal-based catalysts and enzymes.