A mechanism has been identified that could explain how chemical reactions essential to life could have preceded its appearance, providing a stepping stone to the first cells. As much as we have learned about the way natural selection can produce ever more complex species from the simplest self replicating units, big questions remain. Particularly significant is the question of how the organic compounds that make up RNA could have emerged from the oceans of the early Earth.
Our bodies, and those of other living things, use metabolic enzymes to cut and paste elements and compounds to produce the crucial letters out of which the book of life is written. These enzymes are in turn produced by RNA. However, this creates the original chicken and egg problem – where did the RNA come from, given its own complexity?
However, a Cambridge University team have revealed in Molecular Systems Biology that these same reactions can also be triggered by the chemicals believed to have existed in the Archean sea that existed 4-2.5 billion years ago.
“Our results demonstrate that the conditions and molecules found in the Earth’s ancient oceans assisted and accelerated the interconversion of metabolites that in modern organisms make up glycolysis and the pentose-phosphate pathways, two of the essential and most centrally placed reaction cascades of metabolism,” says Dr Markus Ralser, who heads the team that made the discovery.
“In our reconstructed version of the ancient Archean ocean, these metabolic reactions were particularly sensitive to the presence of ferrous iron that helped catalyze many of the chemical reactions that we observed,” Ralser continues. While in many contexts the word ferrous means all iron, in chemistry it refers to iron compounds with an oxidation number of 2+. Geoscientists contributing to the research concluded from studies of the earliest sediments that ferrous iron was common in the oceans before photosynthesis introduced free oxygen to the air and water. More here Metabolic Reactions Could Have Occurred Before The Formation Of Life