Mitochondria are some of the Wise Ape Tribe's best friends. They literally power our high performance, productivity and health. Mitochondria are at the center of many biohacks which is why you may have seen them mentioned on the blog before. It is no exaggeration to say that when your mitochondria are off their game, then you’re off your game. Consider the last time you exercised but didn’t really have the gusto you wanted. Or the last time your brain was foggy, maybe you couldn’t remember where you put your car keys. Performance dips like this link back to the performance of your mitochondria. So what are they and why are they so important? It’s time we get introduced.
Mitochondria are cellular machines, or organelles, that create energy from food. Often they get the nickname cellular power plants. Discovered in 1856 and later named, like so many organelles, for how they appeared under the microscope. Mitochondria comes from the greek words for ‘thread’ and ‘granule’. This is also why the plural form is mitochondria and the singular is mitochondrion (like criteria and criterion).
Mitochondria are not your average, everyday cellular machines. They are special. Divas you might say. They have a double outer membrane and their own genetic material, which is unique. This is because mitochondria were prokaryotic proteobacteria (early bacteria) living in the ancient oceans. But then, and this is cool part, the mitochondrion found new living arrangements by renting space inside eukaryotic cells. Cells that would later evolve into animals. This living arrangement benefited both parties and is called endosymbiosis. The mitochondria benefited with sweet new digs and paid the eukaryotic landlords by producing adenosine triphosphate or ATP. ATP is the energy needed for all cellular processes. If cells were businesses, ATP would be the money. If cells were smartphones, ATP would be the electricity. If cells were cars, ATP would be the gas. If cells were...you get the idea.
This partnership allowed eukaryotic cells to liberate more energy from their food and powered their evolution to more and more complex multicellular organisms. All the way to Wise Apes! Your brain, liver, and muscles are high energy tissues, and so they all have very dense concentrations of mitochondria. Which means they are sensitive to poor mitochondrial performance. As a bonus, mitochondria do more than just create usable energy, they also produce chemicals needed for various cellular functions.
Mitochondria are submarine shaped structures with, as mentioned, a double layered outerwall but there is also a highly folded inner membrane. This is important to know. All this membrane business has implications for health. The membranes are made of lipids (fats) and are sensitive to damage from toxins (such as from the environment or food) or from consuming damaged fats (think fried and processed foods). That inner membrane is key. It’s where the ATP magic happens. For you biochemistry wonks this is where electron carriers NADH and FADH2, from the tricarboxylic acid cycle, enter into the electron transport chain (ETC). Here, at the inner membrane, electrons are shuttled through a series of reactions until paired with oxygen. ATP is produced in the process. The enzymes for all these reactions are embedded within the inner mitochondrial membrane. Unfortunately the ETC can and does leak damaging reactive oxygen species (ROS). Some leakage is a normal part of cell functions, but if the mitochondrial membranes are in rough shape, a result of being overstressed or exposed to toxins or because they were built with shoddy fats, then leakage of ROS can increase. More ROS leakage means more damage to the machinery of your cell, including DNA. If the damage is great enough the mitochondria may activate the cell’s self-destruct sequence.
If you have too few or work them too hard, your mitochondria will become stressed and leak more ROS. In the long term this is bad news. One way to guard against an overload of damaging ROS is to build more and bigger mitochondria. To do this we need to stress the mitochondria in the short term. This is what we are doing when we exercise and we ask our muscles to keep working in low energy conditions (muscle burn anyone?). Mitochondria are stimulated by this lack of cellular energy to grow bigger and divide, becoming more numerous. A process called mitochondrial biogenesis.
Said simply we can’t be mighty unless our ancient bacterial houseguests are mighty first.
Giezen, M. V. (2011). Mitochondria and the Rise of Eukaryotes. BioScience,61(8), 594-601. doi:10.1525/bio.2011.61.8.5
Marín-García, J. (2012). Cell-Death Pathways and Mitochondria. Mitochondria and Their Role in Cardiovascular Disease, 225-241. doi:10.1007/978-1-4614-4599-9_11