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Mitochondrial DNA - mtDNA
The human mitochondrion contains 5–10 identical, circular molecules of DNA. Each consists of 16,569 base pairsMitochondrial DNA (mtDNA) is the
DNA which is located not in the nucleus
of the cell but in the mitochondria.
Mitochondria are parts of the cell that
generate fuel in the form of adenosine
triphosphate (ATP), which drives the
varied machinery of the cell.
Unlike the rest of the cell, the function of
which is defined by the nuclear DNA, the
mitochondria have their own DNA and
are assumed to have evolved separately. Mitochondrial DNA consists of 5-10
rings of DNA and appears to carry 16,569 base pairs with 37 genes (13 proteins, 22tRNAs and two rRNA) which are concerned with the production
of proteins involved in respiration.
However they all need sub-units created
by nuclear DNA in order to work. mtDNA is typically passed on only from the mother during sexual reproduction, meaning that the mitochondria are clones.
This means that there is little change in
the mtDNA from generation to generation, unlike nuclear DNA which changes by 50% each generation. Since the mutation rate is easily measured, mtDNA is a powerful tool for tracking family lineage, and has been used in this role for tracking many species back thousands of generations.
Origin of mitochondrial DNA
The existence of mitochondrial DNA also
supports the endosymbiotic theory, which
suggests that eukaryotic cells first
appeared when a prokaryotic cell was absorbed into another cell without being digested. These two cells then are thought to have entered into a symbiotic relationship, forming the first organelle. The existence of separate mitochondrial DNA suggests that, at one point, mitochondria were separate entities from their current host cells.
reported that it can occasionally be inherited from the father, e.g. in bananas. (Schwartz and Vissing, 2002).
The concept of the Mitochondrial Eve is
based on the same type of analysis,
attempting to discover the origin of humanity by tracking the lineage back in time.
This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License
supports the endosymbiotic theory, which
suggests that eukaryotic cells first
appeared when a prokaryotic cell was absorbed into another cell without being digested. These two cells then are thought to have entered into a symbiotic relationship, forming the first organelle. The existence of separate mitochondrial DNA suggests that, at one point, mitochondria were separate entities from their current host cells.
Mitochondrial inheritance
reported that it can occasionally be inherited from the father, e.g. in bananas. (Schwartz and Vissing, 2002).
The fact that mitochondrial DNA is always (or almost always) maternally inherited enables researchers to trace uterine lineage far back in time. Vil? et al have published studies tracing the matrilineal descent of domestic dogs to 4 individuals [1] .
The concept of the Mitochondrial Eve is
based on the same type of analysis,
attempting to discover the origin of humanity by tracking the lineage back in time.
See also: single origin theory.
References
- Marianne Schwartz and John Vissing, "Paternal Inheritance of Mitochondrial DNA", New England Journal of Medicine, Aug 22, 2002; 347:576-580. [2] (http://www.life.uiuc.edu/csb/213/PDF/mitochondria.pdf)
- "Mitochondria can be inherited from both parents", New Scientistarticle on Schwartz and Vissing's report; [3] (http://www.newscientist.com/news/news.jsp?id=ns99992716)
- Sutovsky, P., et. al. 1999. "Ubiquitin tag for sperm mitochondria."Nature 402(Nov. 25):371-372. Abstract available at [4] (http://dx.doi.org/10.1038/46466) and discussed in [5] (http://www.sciencenews.org/20000101/fob3.asp).
This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License
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