We’ve been spending these last weeks on cell membranes, but new research has discovered the origin of life before membranes. Life before cells, you ask? That’s exactly right. Recent findings suggests that there are such things as metabolisms without bodies. A graduate student at the University of Cambridge found, in his new media, pyruvate — the product of glycolysis — but there were no cells in his media to have produced this compound. He and his PI rushed over to the Earth Sciences department, where they confirmed that such metabolic processes, which produce ATP and are vital to all life on Earth, are indeed capable of operating independently from cells and our lipid membranes in the hot, metallic waters of Earth 4 billion years ago.
As we close this year, I thought that this finding nicely reminds us of what we’re really studying here. Following the evolution of life from the loose metabolic systems by the thermal vents of young Earth to the complex individuals we are today — with our complex emotions, symbiotic microbiota, and entrepreneurial capabilities — we truly appreciate how the biological processes we are studying grow up in this world. Starting with a free metabolic system, we can understand why lipid membranes would be more successful. In this amazing TED talk, Martin Hanczyc shows protocells whose lipid membranes (oil spots) trap simple, 5-chemical compound metabolisms to enable his protocells to move and even replicate (surprise!).
With the evolution of life, we are getting to see this amazing interplay developing between form and function, and between function and form. We see RNA, perhaps catalyzed by inorganic clay molecules, replicate before protein polymerases developed to assume this role more efficiently, membranes entrap metabolisms, and RNA introns (miRNA) take over regulatory roles. As we zoom into the present, we wonder at the intricateness of carbohydrate antigens marked by our immune systems and nucleic acids controlling whole organisms. Biochemistry — It’s Amazing!
Sources (from Prof. Arumainayagam’s CHEM 306):
http://www.newscientist.com/article/dn25471-spark-of-life-metabolism-app#.U2OrB61dXAg
http://www.ted.com/talks/martin_hanczyc_the_line_between_life_and_not_life