Reconstructed Ancient Ocean Reveals Metabolism Existed Before The Evolution Of First Organisms
Scientists recreate ancient oceans and find chemical reactions that mimic our current metabolism.
Another puzzle piece to the origins of the first organisms on earth has been discovered after scientists reconstructed the earth's ancient oceans. Scientists observed metabolism-like reactions that indicate these same reactions could have occurred naturally in our early oceans before the first organisms even evolved.
Researchers at the University of Cambridge recreated the chemical make-up of what they knew to be the earth's earliest ocean right inside their laboratory. What they found were spontaneous chemical reactions used by our modern-day cells to synthesize many of our metabolism's crucial molecules.
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"These results indicate that the basic architecture of the modern metabolic network could have originated from the chemical and physical constraints that existed on the prebiotic Earth," says Dr. Markus Ralser at the Department of Biochemistry at the University of Cambridge and the National Institute for Medical Research, who led the study.
This gave scientists a window into the past on how primitive cells may have learned to synthesize molecules that form RNA, lipids and amino acids, which are all essential to our body's metabolism. These chemical reactions found in the replica ultimately suggest that the metabolism our body currently uses predates the originals of first life.
"In the presence of iron and other compounds found in the oceanic sediments, 29 metabolism-like chemical reactions were observed, including those that produce some of the essential chemicals of metabolism, for example precursors to the building blocks of proteins or RNA," says Ralser.
The discovery indicates that our metabolism may not have been a product of shaped by evolution, but instead the chemical environment that existed in our earth's ancient oceans.
Scientists chose to replicate the Archean Eon, which is the earlier of the two records of Earth's primitive atmosphere and oceans. It is believe that the oxygen content in today's atmosphere slowly developed from the Archean time period.
Before Cambridge University researchers observed the chemical reactions in their mock ocean environment, it was assumed that our metabolic pathways, which are complex metabolic reaction sequences, needed enzymes to work. Enzymes are made from 100 to 1,000 amino acids, which are strung together in a very specific and unique order that only evolution could have designed. They are responsible for all the work being done inside any modern cell in our body and are especially necessary for our metabolism to function. Enzymes are so complex that they were thought to have developed out of the evolutionary process, but the research team's discovery shows quite a different story.
"Our results show that reaction sequences that resemble two essential reaction cascades of metabolism, glycolysis and the pentose-phosphate pathways, could have occurred spontaneously in the earth's ancient oceans," says Ralser.
The Archean ocean's facilitated series of chemical reactions between iron and other metals, which are similar to the core cellular metabolism. Four-billion years ago, Earth's oceans were rich in iron and the atmosphere was bereft of any oxygen, which made iron a more soluble metal and enabled it to act as a catalyst in the absence of enzymes.
Some of the observed reactions could have also taken place in water because they were accelerated by the presence of the metals that researchers used as catalysts. These catalysts sped up the artificially constructed process that otherwise would have taken years to reveal.
"In our reconstructed version of the ancient Archean ocean, these metabolic reactions were particularly sensitive to the presence of ferrous iron which was abundant in the early oceans, and accelerated many of the chemical reactions that we observe," says Ralser. "We were surprised by how specific these reactions were."
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