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Definition of Mitochondrial DNA

  • Medical Author:
    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Mitochondrial DNA: The DNA of the mitochondria. Abbreviated mtDNA. There are 2 to 10 copies of the mtDNA genome in each mitochondrion. The mtDNA molecule is double-stranded and circular. It is very small compared to the chromosomes in the nucleus, and so it contains only a limited number of genes. It is specialized in the information it carries, and it encodes a number of the subunits in the mitochondrial respiratory-chain complex that the cell needs in order to respire. It also contains genes for some ribosomal RNAs and transfer RNAs. Mutations in mtDNA can cause disease. These mutations often impair the function of oxidative-phosphorylation enzymes in the respiratory chain. This is especially manifest in tissues with a high energy expenditure, such as those of the brain and muscle. All mtDNA comes from the oocyte at fertilization. Therefore, inherited mtDNA mutations are transmitted from the mother to both male and female offspring.

Reviewed on 12/27/2018

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