Mitochondria: To most people, they’re little more than a ghostly memory fragment from middle school biology. However, these tiny “powerhouse(s) of the cell” are much more than they seem.
They’re actually the shape-shifting descendants of ancient bacteria that were eaten by a larger archaebacterium billions of years ago. . (If you want to know more about that theory, check out my recent Lateral magazine piece on the scientist who developed that theory.) Mitochondria have complex relationships with other organelles, swim around in our neurons, and make up 1/3rd of the mass of heart cells. In the past year, scientists have learned how to add and remove them with cellular surgeries and how to manipulate them directly.
Mitochondria live in every cell in your body and are essential for human life. As University of California post doc Samantha Lewis pointed out to me: “There’s mitochondrial involvement in almost every disease.”
Yet, we rarely hear or think about our cells’ powerhouses.
Here are seven facts you probably haven’t heard about mitochondria:
1: Mitochondria are interconnected shape-shifters.
[A bone cancer cell with stringy mitochondria highlighted in yellow. Photo by NICHD via Flickr & CC 2.0 License.]
We say “Mitochondria is the powerhouse of the cell” as if mitochondria is a singular word, but actually it’s plural. (The singular of mitochondria is mitochondrion.) However, in most cells mitochondria act as a collective, passing electrons and genetic information from mitochondrion to mitochondrion.
“They’re [descended from] bacteria that divide in a binary fashion,” explained UC Davis cell biologist and mitochondria specialist Jodi Nunnari. “During the course of evolution [the mitochondrial] genome has been greatly reduced. As a consequence of that and the fact that they were reproducing in a new environment, a few of those do mitochondrial fusion.” Mitochondria’s habit of merging sets them apart from all known bacteria. “Bacteria divide, but they don’t fuse,” Nunnari added.
In fact, mitochondria are so tightly connected that many scientists think of them as a membrane network rather than a series of jelly-bean shaped organelles.