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