Mitochondrial DNA Mitochondrial DNA 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 and algae, also in plastids such as chloroplasts. In humans, the 16,569 base pairs of mitochondrial DNA encode for only 37 genes. Human mitochondrial DNA was the first significant part of the human genome to be sequenced. In
Nuclear DNA prophase, metaphase, anaphase, and telophase. A key difference, however, is that during meiosis, each of these phases occurs twice — once during the first round of division, called meiosis I, and again during the second round of division, called meiosis II. Prior to cell division, the DNA material in the original cell must be duplicated so that after cell division, each new cell contains the full amount of DNA material. The process of DNA duplication is usually called replication. The replication is termed semiconservative since each new cell contains one strand of original DNA and one newly synthesized strand of