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Mitochondrial DNA is the small circular chromosome found inside mitochondria. These organelles, found in all eukaryotic cells, are the powerhouse of the cell. [1] The mitochondria, and thus mitochondrial DNA, are passed exclusively from mother to offspring through the egg cell.
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 ]
The mitochondrion is a component of a human cell, and contains its own DNA. Mitochondrial DNA usually has 16,569 base pairs (the number can vary slightly depending on addition or deletion mutations) [24] and is much smaller than the human genome DNA which has 3.2 billion base pairs. Mitochondrial DNA is transmitted from mother to child, as it ...
A major step toward that goal was the completion in 2007 of the full genome of James D. Watson, one of the co-discoverers of the structure of DNA. [21] Whereas a genome sequence lists the order of every DNA base in a genome, a genome map identifies the landmarks.
Illustration of the human mitochondrial DNA with the control region (CR, in grey) containing hypervariable sequences I and II. Mitochondrial DNA became an area of research in phylogenetics in the late 1970s. Unlike genomic DNA, it offered advantages in that it did not undergo recombination.
The human genome is a complete set of nucleic acid sequences for humans, encoded as the DNA within each of the 24 distinct chromosomes in the cell nucleus. A small DNA molecule is found within individual mitochondria. These are usually treated separately as the nuclear genome and the mitochondrial genome. [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]
Nuclear DNA and mitochondrial DNA differ in many ways, starting with location and structure. Nuclear DNA is located within the nucleus of eukaryote cells and usually has two copies per cell while mitochondrial DNA is located in the mitochondria and contains 100–1,000 copies per cell.