Change the Textbooks: This eukaryote completely lacks mitochondria: Mitochondria are membrane-bound components within cells that are often described as the cells' powerhouses. They've long been considered as essential components for life in eukaryotes, the group including plants, fungi, animals, and unicellular protists, if for no other reason than that every known eukaryote had them. But researchers now challenges this notion. They've discovered a eukaryote that contains absolutely no trace of mitochondria at all.
