DNA may be divided into two categories—mitochondrial DNA (mtDNA) and nuclear DNA (nDNA). Mitochondrial DNA is associated with the non-nuclear organelles called the mitochondria—the energy production plants of the cell, generating most of the cellular adenosine triphosphate (ATP). Nuclear DNA resides within the nucleus of eukaryotic organisms. In most organisms, mitochondrial DNA is associated with the maternal hereditary characteristics. Nuclear DNA carries more hereditary information, so it is the preferred choice for forensic investigations; however mtDNA is much more abundant, and may still be available in tissues such as hair, bones, or teeth when nDNA has degraded to the point it can no longer be used. Learn more from informed Bright Hub contributors.