Mitochondrialencoded

Mitochondrialencoded refers to genetic material that is encoded by the mitochondrial genome rather than by the nuclear genome. In most eukaryotes, mitochondria carry their own small, circular DNA molecule that is inherited maternally and exists in multiple copies per cell. In humans, this mitochondrial genome is about 16.5 kilobases and contains 37 genes: 13 protein-coding genes, 22 transfer RNA genes, and 2 ribosomal RNA genes.

The 13 protein-coding genes in the mitochondrial genome encode essential components of the mitochondrial respiratory chain and ATP synthesis. These include subunits of NADH dehydrogenase (complex I), cytochrome c oxidase (complex IV), cytochrome b (complex III), and ATP synthase (complex V). The encoded proteins are synthesized within the mitochondrion using a small set of mitochondrial tRNAs and ribosomes, which differ from their cytoplasmic counterparts. In addition to protein-coding genes, the mitochondrial genome also carries tRNA and rRNA genes that support mitochondrial translation.

Most mitochondrial proteins, however, are encoded by the nuclear genome, translated in the cytosol, and imported into mitochondria. The term mitochondrialencoded is therefore often used to distinguish genes and functions that originate in the mitochondrion itself from those that rely on nuclear-encoded mitochondrial components. The mitochondrial genome is a common focus in studies of evolution, forensic science, population genetics, and human disease, particularly because of its matrilineal inheritance and relatively high mutation rate.