The Origins Of The Energy Of The Mitochondrial Or Mtdna Dna

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The origins of the energy of the mitochondrial or mtdna DNA

Introduction

The main theme in this essay will be the mitochondrial or MTDNA DNA, for this we start from the study of the origins of this cell organelle, known as the energy source, the mitochondria, with the help of the systematic and molecular evolution we can explain why The genome of this organelle has different characteristics from those of the genome present in the nucleus, among the characteristics that we will address are: the fact that the internal space of the mitochondria, the matrix, has numerous amount of mtdna, in terms of the structure we will see That each MTDNA molecule has two chains, one light (L) and another heavy (h) covering the information of 38 genes that in turn are distributed in ribosomal, transfer and other polypeptide trainers, then we will refer to the transcription process of this mtdna for which specific promoters will be required for each of the chains, and other particular transcription factors such as the TFAM and finally there are h The mention of the way it is transferred from the MTDNA that is done only by maternal part.

Developing

Systematic and molecular evolution

The systematic corresponds to the area or branch of biology that is interested in the categorization of species, based on knowing and understanding their history that includes aspects such as their evolution and their phylogenetic background (Raffino, 2019). In turn, molecular evolution is a discipline that works to carry out the necessary studies that lead us to understand the various changes and evolutions suffered by the DNA chain as evolutionary history progresses, these changes can be evidenced in the locus, nucleotides or Other peculiarities of this nucleic acid that are acquiring different transformations as time passes and jointly with the existing species of our planet that evolve and progress according to their needs, allowing us the species and thus be able to know a little more about them and also of their ancestors (molecular evolution, 2019).

In this way we can study the origin of the DNA of the cells, whose location within the internal space of eukaryotic cells is in the nucleus, acquiring the name of nuclear DNA, and in the mitochondria (mitochondrial DNA) in terms of animal cells, And in the vegetables we can locate it present in the organelles called chloroplasts, however in prokaryotic cells it will be found scattered in the cytosol.

From now on, we will concentrate on the mitochondria and its own DNA chain, the MTDNA. Because the mitochondria genome compared or contrast to nuclear DNA presents very different characteristics, the need to raise ideas or hypotheses about the origin of the mitochondrial genome is seen reaching the endosimbiotic theory, this theory raises the idea that around About 2000 million years ago, eukaryotic cells were originated from the colliding The eukaryotic cell was an anaerobic bacterium and with respect to the aerobic bacteria, it constitutes what we know as mitochondria, in this way it is possible to explain why the MTDNA and the nuclear DNA are different, and it is because these two at first, They found in different cells that after endosimbiosis constituted only one, the eukaryotic cell. (Megías, Molist, & Pombal, 2019).

Mitochondria

Present in all aerobic eukaryotic beings, these organelles have the enzymes required in most useful oxidative reactions to produce the fundamental energy so that cellular functions are developed (Quarin, 2005). These cell structures comprise about 20% of the total volume in nucleated cells, it is usual to find them with an ovoid shape and also have their own DNA, autonomous and independent of nuclear DNA (Espino, 2018).

Structure

  • External membrane of the mitochondria: very permeable and contains lipids and proteins: structural (form aqueous channels, porinas) and transfrases and kinases (Seijo, 2012).
  • Internal membrane in the mitochondria: it is very waterproof and is folded inside forming the mitochondrial ridges, it has lipids and transporting proteins (permeasas) (Seijo, 2012). Illustration 1 Mitochondria Structure, (Megías, Molist, & Pombal, 2019)
  • Mitochondrial matrix: Here are the nucleoids that are the place where the DNA molecules, the myitorribosomes and the enzymes required to carry out metabolic processes (Megías, Molist, & Pombal, 2019) are.

Mitochondrial DNA (MTDNA)

Inside each mitochondria and constituting the DNA that is located outside the nucleus (extra nuclear DNA) we manage to find the MTDNA, this is located in structures called nucleoids present in the mitochondrial matrix, with circular structure and closed and formed by a double propeller or chain, this genome covers an equivalent close to about 16500 base pairs which help the coding of a small amount of mitochondria proteins, and in turn the nuclear DNA will encode the remaining amount.

The two mitochondrial DNA chains are called light (L) and heavy (h) This last chain (h) can codify approximately 28 genes, those sequences are distributed in the chain too compact. It is also important to mention that the DNAmt entails information from 38 genes which are distributed in: “2 RNA (12s and 16s), 22arnt and 13 genes capable of encoding polypeptides responsible for assembling several subunits that are part of the complexes that participate in the oxidative phosphorylation. (Fernández, 2006)

In the ADNMT we can find the initiation points of the replication process for the chain (H) in addition to here will be the triggers of the transcription process both for the light chain (LSP) and for the heavy chain (HSP) these are found in A structure called Displacement Loop (D-LOOP) (Justo, 2005).

Transcription and replication of DNMT

The ADNMT has the indispensable polypeptides for the mitochondria work to be carried out correctly, this genome develops the transcription process from the HSP and LSP promoters that are specific to the heavy chain (H) and the light chain (L) Respectively, resulting in a final product of 2 HRNM strand for each chain, in turn this process is closely related to the replication in which an RNA initiator that is emanated by a DNMT strand is essential. To begin this process, the activity of a specific polymerase RNA is required, as well as the mitochondrial transcription factor to “TFAM” (which binds to the ADNMT facilitating the coalition of the RNA polymerase to the initiation point of the transcription) and finally requires of mitochondrial transcription factors B1 and B2 (TFB1M and TFB2M). The TFAM can initiate the transcription in vivo and also in vitro, activating the HSP transcription promoters (at high TFAM concentrations) and LSP (at low concentrations of TFAM) remember that these promoters are located in the MTDNA D-LOOP (Just , 2005).

MTDNA Characteristics

The main characteristics of the MTDNA are summarized at the following points:

  • Polylasmia: high number of Mtdna molecule in cells
  • Maternal inheritance: the transmission or heritability of the MTDNA counts only by the mother.
  • Mutation rate: The MTDNA has a high mutation rate

Polylasmia: Mitochondria contain multiple DNA molecules

This term is used to refer to the large number of MTDNA molecules that can be found inside each mitochondria that exists in the cell, it is possible to observe the collocation between the DNA of the mitochondria and certain particular proteins such as the “Binding Proteins ”, Which together form the nucleoid. The mitochondria has a large number of Mtdna, about 1.000 and 10.000 copies of mtdna per cell that are organized in Nucleoids, from 2 to 10 nucleoids by mitochondria (Fernández, 2006).

Mitochondrial DNA has maternal cytoplasmic heritage:

MTDNA transfer is done in a non -mendelian way by maternal part. Initial both men and women inherit it and possess it, however, women are the only ones who transmit it in inheritance to their progeny. In order to explain this, various arguments or approaches have emerged, among which we have: the remarkable difference in the total MTDNA molecules between the ovule (female gameto) and the male gamete (sperm), a mature ovule has between 100000 and 2000 copies of mtdna, instead a sperm only 50 copies. Another explanation attributes this event is because the intracellular environment of the zigoto, the cytoplasm, where the mitochondria are located, comes from the ovule, unlike what happens in the sperm, since most mitochondria are found in the scourge or tail, but unusually they survive the first cell division. This raises the origin of a precept that indicates the presence of a mechanism in the Oocito that makes it able to recognize and eliminate the mitochondria present in the Paternal Gameto The sperm (Fernández, 2006).

Mutation rate

A characteristic of the MTDNA is that it has an involuntary mutation rate that is in a high proportion with respect to the mutation rate of the nuclear DNA, this particularity can be caused by the high obtaining of free radicals that occur in the mitochondria, these They continue DNA damage that is unprotected by not having protein such as protective histones. Because of this, beings of the same species can have very significant changes in their sequences of up to about 70 nucleotides, even in the same person or individual of any species, it will be in the same individual will be built over time A small difference in the MTDNA. (Montoya, 2000)

conclusion

In this way we conclude that with the contribution of certain areas of biology such as systematic and other disciplines such as molecular evolution and its contribution in the analysis of the origins of this cellular structure: mitochondria, it was possible to explain why the genome of this organelle It has different characteristics from those of the nucleus genome, a phenomenon caused because at first the mitochondria was an independent cell, for this reason it has its own nucleus with different characteristics, among which we can mention the high amount of mtdna that mitochondria pos can go 1.000 and 10.000 copies of mtdna organized in the nucleoids of the mitochondrial matrix, structurally this helical mtdna has two chains, one light (L) and another heavy (h) that cover the information of 38 genes that in turn are distributed in 2 RNA (12s 12s and 16S), 22ARNT and 13 polypeptide trainers genes, for the transcription of this MTDNA, the HSP and LSP promoters that are specific for each chain, a mitochondrial transcription factor to “TFAM” and the mitochondrial transcription factors and the mitochondrial transcription factors will be required B1 and B2 (TFB1M and TFB2M); And finally it is worth mentioning that the transfer of this MTDNA is carried out by the transmission of the cytoplasm (mitochondria container) from the maternal gamete, the ovule, towards the progeny.

Bibliography

  • Espino, c. (2018). Mitochondria. Obtained from Cienciorama: http: // www.Scientic.UNAM.mx/a/pdf/555_ciencioma.PDF
  • Molecular evolution. (2019). Obtained from wikipedia: https: // is.Wikipedia.org/wiki/evolution%c3%b3n_molecular
  • Fernández, e. (2006). The mitochondrial DNA. Obtained from Network Thesis: https: // www.THESISENRED.Net/Bitstream/Handle/10803/795/01.THESIS_EFD_Introduction.PDF?sequence = 2 & isalowed = y
  • Just, r. (2005). Mitochondrial function and biogenesis. Mitochondrial function and biogenesis. Obtained from Network Thesis: https: // www.THESISENRED.Net/Bitstream/Handle/10803/9380/Trjl1de1.PDF?sequence = 1 & isalowed = y
  • Megías, m., Molist, p., & Pombal, M. (2019). The cell, mitochondries. Obtained from Plant and Animal Histology Atlas: https: // mmegias.websites.Uvigo.ES/5-CELIULAS/6-MINOCANDRIAS.PHP
  • Montoya, j. (2000). Mitochondrial DNA. Obtained from Scientific Electronic Library Online: http: // www.Scielo.org.MX/Scielo.PHP?script = sci_arttext & pid = s0036-36342001000200010
  • Quarin, c. (2005). Foreign genome. Obtained from hypertexts from the Biology Area: http: // www.biology.Edu.AR/GENETICS/Foreuclear.htm#use%20Del%20arnmt%20Para%20determinaci%C3%B3n%20de%20parantescos
  • Raffino, m. (2019). Systematic. Obtained from concept.From: https: // concept.of/systematic/
  • Seijo, j. (2012). Mitochondria Catabolism. Obtained from Tirso de Molina: http: // www.Tirsoferrol.org/science/pdf/A14_Mitocondriacatabolismo.PDF

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