DNA mitochondrial

DNA mitochondrial ( DNA MT or mtDNA ) is a circular molecule of DNA contained in the Mitochondrie S of the cells eucaryotes.

Confined inside the Mitochondrie S, Organite S which produce cellular energy, the DNA MT is distinct from DNA contained in the core. This shape of DNA is primarily transmitted by the Mère, which is related to the respective proportions in mitochondries gamètes (Ovule 99% and Spermatozoïde 1%).

It is the ovule coming from the mother, who transmits this DNA to the descent. Indeed the spermatozoon bequeaths only its core at the time of the Fécondation.

Characteristics

The DNA mitochondrial is present in the matrix of the mitochondries. It is a circular molecule (épisome), generally without intron (there exist however some rare will introns autoépissables at mushrooms and yeasts), closed by covalent bond. Its gene size and its contents vary from one species to another. In the higher animals, this size usually varies between: 15,000 and: 24,000 pairs of bases, but can be 10 to 100 times larger at mushrooms and the plants. At the Man, it is made of 2 bits. Composed of: 16,569 pairs of bases, its mass is of 10⁷ dalton S. It is a very small DNA compared to the 3 billion pairs of bases of the nuclear DNA of the human cells. Its quantity at an human being is considerable because a cell has approximately: 2000 mitochondries and a mitochondrion contains approximately 2 to 4 molecules of DNA MT. On the whole, one counts approximately: 4000 molecules of DNA MT by cell.

Genes carried by this DNA

The DNA mitochondrial is entirely occupied by genes and does not contain any repeated sequence. It is transcribed initially in the form of 2 ARN which is then cleaved on the level of the ARNt. All the proteins implied in the protéosynthèse are coded by nuclear genes. The DNA mitochondrial (37 genes) code 22 ARNt, 2 ARNr and 13 membrane proteins implied in the energy production by mitochondrion:

Cytochrome oxydase,
ATP synthase,
NADH déshydrogénase.

This one does not have any system of repair. It will be also noted that the half of the proteins mitochondriales coded by the nuclear genome would be specific of a fabric.

Uses

There are 2 areas hyper-variables HV1 and HV2 in the sequences D-loop. Their comparison between various individuals is interesting from the point of view of the very recent evolution of human, but also to distinguish from the different lines, and to solve problems of filiation or in identification of human remainders and author of crimes. These studies require a sequencing these areas.

In Genetic human, certain characteristics of the DNA mitochondrial make a material of choice of it to try to include/understand the origin of the populations Humaine S:

It is an abundant DNA in the cells, since it is found to thousands of specimens by cell, whereas each gene of the core is not present, him, that in 2 specimens (nonidentical) per cell.
the speed of Mutation is more important than in the nuclear genome, which makes it possible to study recent evolutions as it is the case for the recent origin of Homo sapiens.

Study of the migrations and our recent evolution

Origin of human modern

Thus recent studies showed that all the human Mitochondrie S in the world have a common origin gone back to approximately -150 000 years, in Africa. It is the theory of the Eve mitochondriale.

Relation between the human ones and Men of Néanderhal

Of more than DNA old MT of more than 30.000 years analyzed in the bones of the Man of Néanderthal and compared with human ADNmt, allowed to show that this species is not an ancestor of human current. They form an extinct branch, which would not have given of descendant.

Historical interest and search for filiation

the remainders of the Tsar Nicolas II and his family were identified by comparing ADNmt of the remainders found with Iekaterinbourg with that of the Prince Philip (whose maternal grandmother was the sister of the Tsarina Alexandra). The identification is sure to 99%.
Confirmation of the authenticity of the Relique pertaining to the young person Louis XVII.

August 1st

DNA MT and investigation policiaire

August 1st

See too

External bonds

Details, diagrams…
Comparison sapiens and neandertalensis
mitochondries in the reproduction

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