Human Mitochondrial Genome
The mitochondrial genome is the entire genetic material of the mitochondria. This genome is particularly well known in the man because it has many applications. Indeed, he is involved in many genetic diseases , it can trace the evolution of human populations and may help identify human remains or the perpetrator of a crime.
Summary |
Features
Mitochondrial DNA is present in the matrix of mitochondria. It is a circular molecule ( episome ), usually without intron (though there are few autopissables introns in fungi and yeasts), covalently closed. Its size and gene content varies from one species to another. In higher animals this size usually varies between 15 000 and 24 000 base pairs, but may be 10 to 100 times greater in fungi and plants. In humans, it consists of two strands. Consists of 16 569 base pairs, is its mass of 10 7Daltons. DNA is very small compared to the 3 billion base pairs of nuclear DNA of human cells. Its quantity in a human being is significant because a cell contains about 2000 mitochondria and mitochondrion contains approximately 2-4 molecules of mtDNA. In total, there are about 4000 mtDNA molecules per cell.
gene carried by this DNA
Mitochondrial DNA is fully occupied by genes and contains no repeat. It is transcribed initially in the form of two RNAs that are subsequently cleaved at the level of tRNA. All proteins involved in protein synthesis are encoded by nuclear genes. Mitochondrial DNA (37 genes) encodes 22 tRNAs , 2 rRNAs and 13 membrane proteins involved in energy production by mitochondria:
It has no system of redress. Also, half of mitochondrial proteins encoded by the nuclear genome would be tissue-specific.
Of mutations in these genes are responsible for rare genetic diseases, whose transmission is maternal.
Uses
There are two hyper-variable regions HV1 and HV2 sequences in the loop. Their comparison between different individuals is an interesting point of view of very recent humans, but also to distinguish different strains, and solve problems of parentage or identification of human remains and perpetrator. These studies require sequencing of these regions.
In human genetics , certain features of mitochondrial DNA make it a material of choice to try to understand the origin of populations Humanities :
- It is an abundant DNA in cells, since it is found in thousands of copies per cell, while each of the core gene is present, he, in two copies (not identical) per cell.
- The rate of mutation is more important than in the nuclear genome, which allows the study of recent developments as is the case for the recent origin of Homo sapiens.
Study of migration and our recent
Origin of modern humans
And recent studies have shown that all mitochondria in the human world have a common origin, dated about 150,000 years in Africa. It is the theory of the mitochondrial Eve.
Relation between human and Neanderthal men
In addition, mtDNA older than 30,000 years analyzed in the bones of Neanderthals and compared with human mtDNA, showed that this species is not an ancestor of modern humans. They are a branch off, which would not have descendants.
Historical interest and research affiliation
- The remains of Tsar Nicolas II and his family were identified by comparing the mtDNA of the remains found in Yekaterinburg with that of Prince Philip (whose maternal grandmother was the sister of Tsarina Alexandra ). The identification is certain to 99%.
- Confirmation of the authenticity of the relic belonging to the young Louis XVII.
mtDNA and police investigation
There are multiple copies of mtDNA in mitochondria , so the threshold of mtDNA is sufficient to make investigations or forensic palaeontology.
References
See also
Related articles
- Mitochondrial genome
- Mitochondrion
- Mitochondrial transmission
- Gametogenesis
- Haplogroup
- DNA
- Mitochondrial Eve
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