A harmonic balancer sounds like a crucial part on a spaceship in some pulpy 1950s sci-fi story, or something you need so you can play music with hobos when you're ridin' the rails. However, it's actually an important part on your engine that helps your crankshaft last as long as possible.
U.S. National Library of Medicine (5.00 / 1 vote) Rate this definition: Mitochondria. Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae.
Mitochondria (illustration) are structures within cells that convert the energy from food into a form that cells can use. Each cell contains hundreds to thousands of mitochondria, which are located in the fluid that surrounds the nucleus (the cytoplasm).