Carnitine and coenzyme Q10 both work in the mitochondria of our cells. The mitochondria are tiny, cucumber-shaped "factories" that are responsible for turning the raw food materials that we eat into ATP, the universal energy currency of the cell.

Let's take a guided tour into one of your mitochondria to see carnitine and coQ10 in action.

The mitochondrial factory has two main compartments: the outer compartment, called the intermembrane space, and the inner compartment, or matrix. The intermembrane space functions as a "shipping and receiving" area for raw food materials, while the matrix is the main "factory floor" where the serious industrial activity takes place.

To begin the tour, we first enter the intermembrane space. Here, hundreds of different molecules (shown here in red) directly descended from the sugars and fats that you ate yesterday are milling around waiting to be routed onto the factory floor for further processing.

The smaller fatty acids (a type of fat molecule) are able to pass through the door to the matrix with no problem. Bulkier fatty acids, known as "long-chain fatty acids," however, require some extra help to get into the matrix. It's the responsibility of carnitine (the little blue guy at the door) to haul these oversize and reluctant long-chain fatty acids (like the big yellow one) into the matrix through special gateways. Carnitine also escorts extra fatty acids and fatty acid derivatives out of the cell for elimination in the urine.

If we were to sneak through the gate behind carnitine and its load of long-chain fatty acids, we'd find ourselves on the bustling factory floor of the mitochondrion. Here carnitine drops off its load of fatty acid and returns to the intermembrane space to pick up the next load.

In the matrix, fatty acids are disassembled into smaller units and fed into a giant hopper where their electrons (E-) are stripped. These processes are known as "beta oxidation" and the "tricarboxylic acid cycle." Electrons extracted from raw materials then travel along an assembly line made up of four large protein complexes called the "electron transport chain" or "respiratory chain."

Enter coQ10, our electron transport line man (the guys in lavender). It is the job of coQ10 to see that electrons are transferred smoothly from one protein complex in the respiratory chain to the next. CoQ10 also works the night shift to clean up hazardous free radicals that are a by-product of the respiratory chain.

The potential energy of the electrons being harvested is eventually used to make ATP (green). ATP is a molecule that contains stored energy, much like a battery. The ATP created in the mitochondria is shipped out to the far corners of the cell to power such things as muscle fiber contraction and many other cellular processes.

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