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In humans, mitochondrial DNA (mtDNA) forms closed circular molecules that contain 16,569 [4] [5] DNA base pairs, [6] with each such molecule normally containing a full set of the mitochondrial genes. Each human mitochondrion contains, on average, approximately 5 such mtDNA molecules, with the quantity ranging between 1 and 15. [ 6 ]
Mitochondrial DNA is a small portion of the DNA contained in a eukaryotic cell; most of the DNA is in the cell nucleus, and, in plants and algae, the DNA also is found in plastids, such as chloroplasts. [3] Human mitochondrial DNA was the first significant part of the human genome to be sequenced. [4]
Sexual reproduction, where offspring result from the fusion of gametes from two parents, is the most common form of biparental inheritance. While less common, cases of biparental inheritance in extranuclear genes have been documented, such as biparental inheritance of mitochondrial DNA, or chloroplast DNA in plants. [1]
We previously thought mitochondrial DNA could only be passed on by mothers. Skip to main content. 24/7 Help. For premium support please call: 800-290-4726 more ways to reach us ...
[2] [3] [4] In testing 172 sheep, "The Mitochondrial DNA from three lambs in two half-sib families were found to show paternal inheritance." [5] An instance of paternal leakage resulted in a study on chickens. [6] There has been evidences that paternal leakage is an integral part of mitochondrial inheritance of Drosophila simulans. [7]
[1] At birth, all copies of mitochondrial DNA are thought to be identical in most humans. [2] Microheteroplasmy is mutations of up to about 2−5% of mitochondrial genomes, and is present in most adults. This refers to hundreds of independent mutations in one organism, with each mutation found in about 1–2% of all mitochondrial genomes. [3]
Branches are identified by one or more unique markers which give a mitochondrial "DNA signature" or "haplotype" (e.g. the CRS is a haplotype). Each marker is a DNA base-pair that has resulted from an SNP mutation. Scientists sort mitochondrial DNA results into more or less related groups, with more or less recent common ancestors.
The Cambridge Reference Sequence (CRS) for human mitochondrial DNA was first announced in 1981. [ 2 ] A group led by Fred Sanger at the University of Cambridge had sequenced the mitochondrial genome of one woman of European descent [ 3 ] during the 1970s, determining it to have a length of 16,569 base pairs (0.0006% of the nuclear human genome ...