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
Neuronal cell cycle neurons, which are able to replicate their DNA without neuronal death (Smith et al., 2000). Neurons that are Rb deficient have also been found to re-enter the cell cycle and survive in a 4C DNA state (Lipinski et al., 2001). Duplication of DNA can lead to neuronal diversification in vertebrates, as seen in observations in the developing chick retina. These neurons re-enter the cell cycle as they travel to the ganglion cell layer when they are activated by p75NTR. These neurons are unable to enter mitosis and are stuck in a 4C DNA content state. Cell cycle re-entry by p75NTR