Mitochondrial-DNA.jpg

illustration of a cell with tiny oval-shaped mitochonria, and even tinier round DNA

National Institutes of Health, National Human Genome Research Institute, Talking Glossary of Genetic Terms, Mitochondrial DNA. / Public domain

Mitochondrial DNA is the small circular chromosome found inside mitochondria. The mitochondria are organelles found in cells that are the sites of energy production. The mitochondria, and thus mitochondrial DNA, are passed from mother to offspring.