Mitochondrial DNA is DNA that is present inside the mitochondria of a cell. Mitochondrial DNA is not part of the DNA found in cellular chromosomes.
Mitochondrial DNA has 37 genes essential for normal function. Thirteen of these genes are involved in oxidative phosphorylation. The rest of the genes are involved in making transfer RNA and ribosomal RNA molecules. These RNA molecules are chemically related to DNA and help construct amino acids, or protein building blocks, into functioning proteins.
Mitochondria, located in the cytoplasm of a cell, convert energy from food into a substance that cells can use. The energy-producing process is called oxidative phosphorylation, and it creates adenosine triphosphate, which is a cell’s main energy source. Cells contain from hundreds to thousands of mitochondria.