mitogenome

Mitogenome, short for mitochondrial genome, is the genetic material contained within mitochondria, the organelles that generate most cellular energy. In most animals the mitogenome is a compact circular double-stranded DNA molecule of about 16,000–17,000 base pairs. It typically encodes 37 genes: 13 protein-coding genes that participate in oxidative phosphorylation, 22 transfer RNA genes, and 2 ribosomal RNA genes. The remainder consists of noncoding regions, including control regions such as the displacement loop (D-loop) that regulate replication and transcription. Plant, fungal, and many protist mitochondrial genomes are more variable in size and structure, often larger and sometimes multipartite, with more introns and occasional gene transfers from the nucleus or chloroplasts.

Inheritance and evolution: In most animals, mtDNA is transmitted maternally and exhibits a relatively fast rate of sequence evolution compared with nuclear DNA, making it useful for phylogenetics and population genetics. Recombination is rare in animal mitochondria but is more common in plants, contributing to rearrangements and size variation. Some lineages show paternal leakage or heteroplasmy, in which more than one mitogenome is present in a cell.

Applications and analysis: Complete mitogenome sequences are widely used for species identification, phylogenetic analyses, population genetics, and forensic genetics. Analyses focus on gene content and order, control-region variation, and overall base composition; annotation must account for genetic-code differences among lineages.