An anonymous reader writes: Scientists have found a eukaryote microbe that completely lacks mitochondria, which are the powerhouses inside eukaryotic cells, the type of cells that make up humans, animals, plants and fungi. All eukaryotic cells contain a nucleus, organelles and mitochondrion. Scientists believe they were once free-living bacteria that got engulfed by primitive, ancient cells that were evolving to become what they are today. Anna Karnkowska, a researcher in evolutionary biology at the University of British Columbia in Vancouver, found a gut microbe that contains no trace that it made any mitochondrial proteins at all. “That should theoretically kill the cell — it shouldn’t exist,” she said. The researchers learned that these cells use a kind of machinery that is different than relying on mitochondria to assemble iron-sulfur clusters, which is thought to be a mitochondrial function. Michael Gray, biochemist at Dalhousie University in Halifax, Nova Scotia, calls the discovery of a eukaryote without any vestige of mitochondrion, “unprecedented.” He adds, the results do not negate the idea that the acquisition of a mitochondrion was an important and perhaps defining event in the evolution of eukaryotic cells, because this organism’s ancestors had mitochondria that were then lost after the cells acquired their non-mitochondrial system for making iron-sulfur clusters.
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