Vertebrate Mitochondrial DNA

Abstract

The mitochondria of eukaryotes contain a genome of their own, the mitochondrial DNA (mtDNA). The mitochondrial genome of metazoans is a covalently closed circular molecule with a size of about 16 kilonucleotide pairs (kntp). Considerable length differences exist between organism groups (e.g. ciliata > 40 kntp, fungi 17–176 kntp, higher plants 200–800 kntp). In vertebrates, the genome encodes 2 rRNAs, 22 tRNAs, and 13 proteins involved in oxidative phosphorylation. This is a multicopy genome with a predominantly maternal inheritance, and in vertebrates, a high substitution rate. A number of mtDNA mutations in humans have been associated with muscular or neurological disease, and the accumulation of mutations in this genome may result in premature aging and contribute to the natural aging process. MtDNA has been one of the main tools used in studies of human evolution and has provided some of the strongest evidence for an African origin of modern humans. This review is biased toward the vertebrate genome due to the wealth of information available from this group. A number of unique characteristics set vertebrate mitochondrial DNA apart from the mtDNA in other organisms, justifying this focus.