Aging and Disease as Caused by Mitochondria

Mitochondria are the powerhouse of the cell. Their sole responsibility is to provide energy for the cell. They do this by synthesizing a molecule known as ATP, which the cell uses as energy. Mitochondria are different from the rest of the cell organelles because they contain their own DNA outside the nucleus.
Mutations in this DNA have been found to be linked to Alzheimer”s and other neurodegenerative diseases. Mutations in the DNA cause the mitochondria to function in other ways than it usually does. Generally, these mutations cause the mitochondria to produce ATP less efficiently. Nuclear DNA is a lot less prone to these mutations because it has things that check and fix problems when they occur.
Mutations are passed from cell to cell randomly. When a cell divides it can pass both normal mitochondria and mutated ones in any ratio to the two daughter cells. These mutations can only be inherited through your mother since she is the one that provides all the mitochondria at conception.
In the process of making ATP oxygen free radicals are produced. These free radicals are very harmful and destructive causing breakdowns in mitochondria and more mutations in its DNA. The mutations are believed to produce free oxygen radicals. Mitochondria after long periods of time are able to produce less and fewer amounts ATP because of the free radicals deteriorating them. This for most of the cells is usually not that much of a problem because cells make excess ATP. But in mutated cells that are big ATP consumers, like brain and muscle cells, these cells can sometimes lack enough ATP to function and die because of it.
Work was done at the University of California, San Francisco to prove that oxygen radicals breakdown mitochondria. They used mice that lacked an enzyme (Manganese superoxide dismutase) that neutralizes free radicals during oxygen metabolism. The mice died within 10 days and samples taken of mitochondria from the heart tissue of the mice revealed the mice died because of problems with the mitochondria.