Researchers say that only 99% of DNA is contained within your chromosomes and the genes (letters spelling out words, phrases, and sentences). Where is the remaining 1%? Turns out it is in your mitochondria: tiny rod-shaped organelles—power generators (energy factories) inside the cell—that convert oxygen and nutrients into adenosine triphosphate (ATP). This is the chemical energy "currency" of the cell that powers all its metabolic processes. If it stops working properly you are out of energy. Period. Unlike chromosomal DNA that is inherited from both parents, you get all your mitochondrial DNA from your mother. What happens when mitochondrial DNA mutates? More next time.