Mitochondria Primer 2 - The Electron Transport Chain

October 01, 2018

References: Mitochondria and the Future of Medicine, Youtube, ATP-Synthase on Youtube

 This is heavy science, so hang in with me here. I'll try to give you the simplest analogy that allows you to understand what is happening in your mitochondria. It sounds arcane, but this is the nugget of how long you live, what diseases you have when you die. All those little details, which may be of interest to you.  In essence, they extract the energy inherent in high energy hydrogens that are attached to carbon atoms (what we call food: fat or carbs), and reattach the hydrogen atoms to oxygen and extract that high level of energy into activated ATP molecules. That makes water and carbon dioxide as end products. It's as though the hydrogen atoms are spinning faster around carbon atoms and have more momentum. When they get attached to oxygen to make water, they are spinning slower and have lower momentum, or less energy. 

The extraction of that energy is very elegant as it transfers the latent energy that plants made by capturing light rays from the sun and storing energy in the form of carbs, fats or proteins. Animals can then extract that latent "momentum" energy back into usable fuel. The molecule ATP, adenosine-tri-phosphate has 3 phosphate atoms on it which pick up that latent energy and use it as the universal currency of energy in your cell. Whew. If you got that, you're good.  The extraction process happens by separating the electrons of hydrogen from their protons and moving the protons across the inner membrane of the mitochondria, thereby building up a pool of high energy protons in a reservoir that then cascades downward, activating ATP-synthase as they do so. 

 The concept of a "pool" or "reservoir" requires the sequestration of the high energy protons on one side of the membrane. Think of it like a dam. Your mitochondria pump "water" up into the reservoir and then extract the energy like a dam with spinning turbines extracting electricity. The downhill cascade of protons makes ATP with the energy from the electron transport chain. It has 4 "Complexes" of proteins. The first two "Complexes" called Complex I and II pass off their electrons via CoQ10 to Complex III that then passes them on cytochrome C, and then to Complex IV to then make water. 

Here is the critical rub. Electrons are odd creatures. They are sometimes waves, and sometimes particles. The poor electron transport chain has to deal with these slippery critters and doesn't always get it right. About 2% of them slip away and wander around, attaching themselves to other molecules. High energy electrons are dangerous. They attach to oxygen and make oxygen radicals that damage and destroy other proteins. Alarm, alarm. This is a big problem. We've had a time figuring all this out. You see, Complex I is actually 46 smaller proteins all assembled together. It pulls out the first 4 electrons to pump upstream and is the primary site of electron escape. 

This is exactly where CoQ10 either captures or mops up those loose electrons. But that's enough for you to know. We need to know that electrons can get away, that they aren't universally captured by the proteins assigned to process them, that CoQ10 is a critical compound and that ATP is made by all of this process. From there we can understand the problems with an illness that happens when those processes don't happen smoothly. That will be next week. 

 www.what will work for me. I've spent my career combating carbon monoxide poisoning in the ER. Every winter as furnaces go on, various combinations of folks come to the ER with headaches and lethargy. Carbon monoxide plugs up the electron transport chain so that the mitochondria are literally plugged up. Electrons can't go downhill. The mitochondria die if the CO isn't forced back out with high-pressure hyperbaric oxygen. Same problem with cyanide. It blocks the final steps. If your mitochondria die, you follow shortly thereafter. For starters, keep your mitochondria safe by making sure you have a carbon monoxide monitor in your home.   

Pop Quiz

  1. Carbs and fats, made by plants have latent energy in them captured from sunlight. T or F   Answer: True. The essence of life on earth is given by the sun.
  2. That potential latent energy can be captured by sequestering it on one side of the mitochondrial inner membrane, like pumping water up into a holding tank or reservoir? T or F Answer: Precisely. Capturing the energy in reverse to be used in a form of "energy currency" inside our cells.
  3. The name of that energy currency is ADP. T or F                      Answer. False. Ok, I'm being mean. Close. It's ATP. ATP is Adenosine TRI Phosphate. That's the energy currency. When it gives one Phosphate away, it becomes ADP or Adenosine DI Phosphate. The mitochondria remake ADP into ATP all day long. Each molecule of ATP leaves the mitochondria, activates something somewhere in the cell, and comes back into the mitochondria 10,000 times a day. Round and round.
  4. The Electron Transport Chain is the mechanical means by which the energy of the electrons is extracted. T or F                                    Answer: that's it. The smallest machine.
  5. It's a perfect machine. T or F. Answer:                           False. Electrons are "uncertain" - sometimes waves and sometimes particles (Heisenberg uncertainty principle). That makes them slightly unpredictable. They slip out the cracks. Then all hell breaks loose because high-energy electrons in the wrong places cause damage. Oxidants. Reactive oxygen species. Etc. Like spilling gasoline. One match from disaster.