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A mitochondrial genome is a collection of genetic information carried in the mitochondria, organelles found in the cells of eukaryotic organisms like humans and other complex animals. This DNA is separate from that carried in the chromosomes at the cell’s nucleus, which make up the bulk of the organism’s overall genome. Researchers exploring genetic inheritance have sequenced the mitochondrial genome of a number of organisms, including humans, to collect information on this rather unique aspect of genetics.
Several features set the mitochondrial genome apart from other genetic material in the body. First of all, it is inherited solely through the mother, which can have useful implications for tracking generational changes, relationship, and inheritance. Additionally, it has an unusually high mutation rate when compared to the chromosomal genome. Furthermore, it is believed to be the traces of DNA from organisms which were once wholly independent, and later absorbed by early living cells to provide symbiotic benefits.
37 genes are carried in the mitochondrial genome. They carry information the mitochondria use to perform their primary function, which is the generation of energy for cellular activities. The mitochondria can produce several key proteins, transfer RNA, and ribosomal RNA using the blueprints found in their DNA. Sequencing the mitochondrial genome can provide useful clues into inheritance not just within species, but throughout evolutionary history. Researchers have, for example, used this DNA to track groups of people to single common female ancestors.
Studies can also be important for understanding mitochondrial disorders. These conditions can be caused by errors in the mitochondrial DNA that erode the function of these important organelles. Without functioning mitochondria, the cells may not be able to perform key tasks. In people with Leber’s hereditary optic neuropathy, for example, vision loss occurs in childhood to early adulthood because of malfunctioning mitochondria. Women can pass the condition on to their children, but men will not, because the mitochondrial genome is only carried in the eggs, not the sperm.
Public databases provide information on mitochondrial DNA from an assortment of organisms. These databases can help researchers identify individual genes, and allow them to compare genes from healthy and diseased organisms to look for the specific errors in DNA that lead to genetic conditions. Researchers in fields like gene therapy can use this information to determine if it is possible to repair DNA to restore functionality, and can use it for embryonic diagnosis and screening to check for signs of common genetic disorders.