Scientists have developed an interesting new theory to explain the origin of life on Earth.
Recent experiments done by researchers have demonstrated that the main chemical reactions needed for supporting life today could have been facilitated with ingredients that were likely found 4 billion years ago on the planet.
The study has been published in the journal Nature Communications on Jan. 8. It was carried out by a research team, which included members from The Scripps Research Institute, NASA Center for Chemical Evolution, and National Science Foundation.
"This was a black box for us," said study author Ramanarayanan Krishnamurthy. "But if you focus on the chemistry, the questions of origins of life become less daunting."
Citric Acid Cycle
The scientists studied arrays of chemical reactions that create a citric acid cycle. It is a cycle that every organism, which is aerobic in nature, relies on for releasing the energy stored in their cells.
In earlier studies, scientists took an approach where they assumed that early life needed the same molecules for the cycles of citric acid that life requires today. The drawback with that viewpoint, however, is that these biological molecules are weak. The chemical reactions needed in the cycle would not have been present in the primordial years of the planet as the ingredients did not exist yet.
A New Study
To conduct the new study, the researchers first started with the chemical reactions. They wrote a chemical recipe and then figured which molecules from a young Earth could have made the cut as ingredients.
The research shows how two cycles, non-biological in nature, called the malonate cycle and HKG could have come together to catalyze a crude form of the citric acid cycle. The two cycles utilize reactions, which work the same primary chemistry of a-ketoacids and b-ketoacids similar to the citric acid cycle.
The scientists discovered that they could generate a citric acid’s end products like amino acids as well as carbon dioxide. The research team thinks that the availability of biological molecules such as enzymes could have replaced the non-biological molecules in the primary reactions to make them more efficient and elaborate.
Krishnamurthy explained that just the molecules’ nature had changed but the chemistry could have stayed the same over billions of years. Biological needs over time shaped the evolution of the molecules to be more complicated.
The reactions are made more plausible with the presence of a molecule known as glyoxylate at the center of the reactions. It could have been present on a young Earth and plays a role in today’s citric acid cycle.