Mitochondrial DNA (mtDNA) is a type of genetic material found in the mitochondria, which are the energy-producing structures within cells. Unlike the DNA found in the nucleus, mtDNA is inherited only from the mother and is passed down through generations. It plays a crucial role in producing proteins essential for the mitochondria's function and energy production. Mitochondrial DNA is relatively small and circular, containing 37 genes. These genes are involved in the processes that convert food into energy, making mtDNA vital for cellular metabolism. Scientists study mtDNA to understand evolutionary relationships and trace maternal lineage in various species, including humans.