Mitochondrial DNA (mtDNA) is a type of DNA located outside the nucleus in the liquid portion of the cell (cytoplasm) and inside cellular organelles called mitochondria. Mitochondria are found in all complex or eukaryotic cells, including plant, animal, fungi, and single celled protists, which contain their own mtDNA genome.
In 1987 Rebecca Louise Cann, Mark Stoneking, and Allan Charles Wilson published "Mitochondrial DNA and Human Evolution" in the journal Nature. The authors compared mitochondrial DNA from different human populations worldwide, and from those comparisons they argued that all human populations had a common ancestor in Africa around 200,000 years ago.
James M. Cummins published "The Role of Maternal Mitochondria during Oogenesis, Fertilization and Embryogenesis" 30 January 2002 in the journal Reproductive BioMedicine Online. In the article, Cummins examines the role of the energy producing cytoplasmic particles, organelles called mitochondria.
Mitochondrial diseases in humans result when the small organelles called mitochondria, which exist in all human cells, fail to function normally. The mitochondria contain their own mitochondrial DNA (mtDNA) separate from the cell's nuclear DNA (nDNA). The main function of mitochondria is to produce energy for the cell.