Detailed introduction about Mitochondrial DNA

Mitochondria are the genetic material in mitochondria that have cell fertility) and are a special form of deoxyribose found in cell mitochondria. Mitochondria are organelles that provide energy (ATP) to cells. A mitochondrion generally features several DNA molecules.

Carrying its own DNA, mtDNA of these genes, and the energy of these genes may cause diseases. Although diseases can cause many changes, the brain, nerves and other energy-consuming organs are usually affected. Most of the egg cells and related diseases are inherited from the mother.

Composition structure

Researchers have invented a method to transform the genetic material of egg cells, replacing egg cells carrying the wrong mitochondrial DNA with egg cells with healthy mitochondria. As a result, the embryo will carry nuclear DNA from the mother and father, as well as mitochondrial DNA from the egg donor.

Although mtDNA can synthesize proteins, its types are very limited. So far it is known that the RNA and polypeptides encoded by mtDNA are: 2 types of rRNA (12S and 16S) in the mitochondrial ribosome, 22 types of tRNA, and 13 types of polypeptides (each containing about 50 amino acid residues). Most of the proteins that make up the various parts of the mitochondria are encoded by nuclear DNA and synthesized on the cytoplasmic ribosome before being transported to their respective functional sites in the mitochondria. Because of this, the genetic system of mitochondria still depends on the genetic system of the nucleus. Therefore, mitochondria are semi-autonomous organelles.

Mitochondrial genome: The mitochondrial genome is a naked DNA double-stranded molecule, mainly circular but also linear molecules. The size of the mitochondrial genome varies from species to species. In general, the mitochondrial genome in animal cells is small, ranging from 10 to 39 kb; in yeast, it is 8 to 80 kb; all are circular. Protozoa such as Tetrahymena and Paramecium are 50kb and are linear molecules. The mitochondrial genome of plants is much larger than that of animals, but it is also much more complicated. The size can range from 200 to 2500 kb. For example, in the Cucurbitaceae, it is 330 kb for watermelon and 2500 kb for cantaloupe, a difference of up to 7 times!

The main function

Copy

mtDNA can replicate itself, and its replication is also carried out in a semi-reserved manner. It is proved by isotope labeling that the time of mtDNA replication is mainly in the S phase and G2 phase of the cell cycle. DNA first replicates, then mitochondria divide. Its replication is still controlled by the nucleus, and the DNA polymerase required for replication is encoded by nuclear DNA and synthesized on the cytoplasmic ribosome.

Genetic

Since mitochondria are passed through egg cells, related diseases will be inherited from the mother. The technology may help women with pathogenic mitochondrial gene mutations give birth to healthy children.

There are mitochondria in all cells of the human body (except red blood cells), but only women’s mitochondrial genes can be passed on to offspring with their eggs. mtDNA is the abbreviation of Mitochondrial DNA (mitochondrial DNA), which is the material that carries the mitochondrial genetic code. A man’s mitochondria only accompany the man for his entire life, and then end, and cannot be passed on to offspring. mtDNA shows maternal inheritance. The structure type of mtDNA is an important indicator reflecting the maternal context. By testing the mtDNA of modern people, it is possible to clarify the maternal blood relationship of people of various ethnic groups and localities. By detecting the mitochondria of ancient corpses, it is possible to clarify the matrilineal blood relationship, historical stories, migration routes, and the nationalities and identities of historical celebrities among various ethnic groups in history.

The mother contributes 50% of hereditary genes to her children and has the same influence on hereditary characteristics as her father. "Mitochondrial DNA" is a genetic gene that is only passed through the maternal line. Men can also inherit "mitochondrial DNA" from their mothers, but they cannot pass it on to their offspring.

Basic nature

Compared with the nuclear genome, the mitochondrial genome has the following properties:

All genes are located on a single circular DNA molecule.

The genetic material is not covered by the nuclear membrane.

DNA is not compressed by protein.

The genome does not contain so many non-coding regions (regulatory regions or "introns").

Some codons are different from universal codons. On the contrary, it is similar to some purple non-sulfur bacteria.

Some bases are part of two different genes (overlapping genes): a certain base serves as the end of one gene and at the same time as the beginning of the next gene.

Mitochondrial DNA survives much longer than DNA and is inherited from the mother, so it is ideal for confirming family relationships.

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