Mitochondrial DNA (
mtDNA or
mDNA) is the
DNA located in
mitochondria, cellular organelles within
eukaryotic cells that convert chemical energy from food into a form that cells can use,
adenosine triphosphate (ATP). Mitochondrial DNA is only a small portion of the DNA in a eukaryotic cell; most of the DNA can be found in the
cell nucleus and, in plants, in the
chloroplast.