Mitochondrial genetics and inheritance have the following properties:
• Mitochondria have their own small circular genome called mitochondrial DNA or mtDNA. It contains 37 genes that encode proteins involved in mitochondrial function and energy production.
•mtDNA is inherited maternally. Egg cells contain many mitochondria, while sperm cells typically have few to none. So mtDNA is passed down from mothers to their children.
• There is no recombination of mtDNA. All the mtDNA comes from the maternal lineage, so there is a direct genetic trail from maternal ancestors to their descendants.
• mtDNA mutates at a higher rate than nuclear DNA. This higher mutation rate makes mtDNA useful for evolutionary studies and for tracing human maternal ancestry and migration patterns.
• mtDNA shows high sequence diversity across the human population. There are many lineages and haplogroups that can be used to trace shared maternal ancestry.
• Diseases caused by mutations in mitochondrial genes often show maternal inheritance patterns. Mitochondrial diseases can affect energy production and many other cellular functions.
• An individual's mitochondria may contain a mixture of mtDNA sequences (a phenomenon called heteroplasmy). However, a bottleneck effect during transmission to the next generation can result in only one of the types being passed on (homoplasmy).
• Mitochondrial replacement therapy can be used to prevent transmission of mitochondrial diseases caused by mutations in mtDNA. Donor mitochondria with normal mtDNA are used to replace the prospective mother's mitochondria in egg cells or zygotes.
That covers some of the key properties of mitochondrial genetics and mitochondrial inheritance.