Reparation - a property of living cells to fight the different DNA damage.In the outside world there are many factors that could cause irreversible changes in a living organism.To preserve its integrity and avoid pathological mutations incompatible with life, there must be a system of self-recovery.As it violated the integrity of the genetic material of cells?Consider this question in more detail.Also, find out what are the body's repair mechanisms and how they work.
Abnormalities in DNA
deoxyribonucleic acid molecule can be broken in the course of the biosynthesis as well as under the influence of harmful substances.Negative factors in particular include temperature or physical forces of different origin.If the failure has occurred, the cell starts the repair process.So begins the restoration of the original structure of the DNA molecule.For reparation meet specific enzyme systems present within the cells.With the inability to carry out the restoration of the individual cells are connected, some of the disease.The science that studies the processes of repair - is biology.Within the discipline we conducted a lot of tests and experiments, due to which it becomes easier to understand the recovery process.It should be noted that the mechanisms of DNA repair are very interesting as the history of the discovery and study of this phenomenon.What factors contribute to the beginning of the recovery?To start up the process, it is necessary that DNA stimulator affected tissue repair.What is it, tell a little more detail below.
History of discovery
This surprising phenomenon began studying American scientist Kellner.The first significant discovery in the way the study was the repair of such a phenomenon as photoreactivation.This term Kellner called the effect of reducing the harm from ultraviolet radiation in the subsequent processing of damaged cells bright stream of light in the visible spectrum.
"Light Recovery"
Later studies Kellner got a logical continuation in the works of American biologists Setlou, Rupert and others.Thanks to the work of this group of scientists has been reliably established that photoreactivation is a process that is started by a special ingredient - an enzyme that catalyzes the cleavage of thymine dimers.They, as it turned out, were formed in the course of the experiments under the influence of ultraviolet light.This bright visible light ran the action of the enzyme, which contributed to the splitting of dimers and restore the original state of the damaged tissue.In this case, we are talking about a light variety of DNA repair.We define it more clearly.It can be said that the repair of light - this recovery when exposed to light after the original structure of DNA damage.However, this process is not only contributing to the elimination of defects.
"The dark" recovery
Shortly after the opening of the light has been detected dark repair.This phenomenon occurs without any influence of light rays of the visible spectrum.This resilience was found during the investigation of some bacteria sensitivity to ultraviolet rays and ionizing radiation.Dark repair of DNA - is the ability of the cells to remove any pathogenic changes of deoxyribonucleic acid.But it must be said that this is not a photochemical process, in contrast to the light of recovery.
mechanism "dark" Damage Cleanup
Observations of bacteria have shown that after a certain time after the single-celled organism received a portion of the ultraviolet, so that some parts were damaged DNA, the cell regulates its internal processes in a certain way.As a result of the modified piece of DNA is cut from a common chain.The resulting gaps as necessary to re-fill material from amino acids.In other words, re-synthesis of DNA carried out.The discovery by scientists such thing as dark repair tissue - this is another step in exploring the amazing defensive abilities of the animal and the human.
How does the repair system
experiments have revealed the mechanisms of recovery and the very existence of this power held by a single-celled organisms.But the repair processes inherent in living cells of animals and humans.Some people suffer from xeroderma pigmentosum.This disease is caused by a lack of the ability of cells resynthesize damaged DNA.Xeroderma inherited.Of what is repair system?Four of the enzyme, which keeps the repair process - a DNA helicase, -ekzonukleaza, polymerase and -ligaza.The first of these compounds is able to detect damage in the chain molecules of deoxyribonucleic acid.It not only recognizes, but also cuts the chain in the right place, to remove the section of the modified molecule.Deposit removal is carried out with a DNA exonuclease.Next, the synthesis of a new section of the molecule of deoxyribonucleic acid of the amino acids with the aim to completely replace the damaged segment.Well, the final chord of the complex biological procedure performed by the enzyme DNA ligase.It is responsible for the attachment to the damaged portion of the synthesized molecule.Once all four enzymes have done their work, the DNA molecule is completely updated and all the damage in the past.So smoothly working mechanisms within the living cell.
Classification
Currently scientists are the following varieties repair systems.They are activated depending on various factors.These include:
- reactivation.
- Recombination recovery.
- Reparation heteroduplexes.
- excision repair.
- reunification of non-homologous ends of DNA molecules.
all single-celled organisms have at least three enzyme systems.Each of them has the ability to carry out the recovery process.These systems include: direct, excision and postreplicative.The three kinds of DNA repair have prokaryotes.As for eukaryotes, it is at their disposal, additional mechanisms, which are called Miss-mathe and Sos-repair.Biology examined in detail all of these kinds of self-repair of the genetic material of cells.
structure of additional mechanisms
Direct repair - it is the least complicated way of getting rid of the pathological changes in the DNA.It is carried out special enzymes.Thanks to them, restore the structure of the DNA molecule it is very fast.Usually, the process takes place during one stage.One of the above enzymes is O6-methylguanine-DNA methyltransferase.Excision repair system - a type of self-healing of deoxyribonucleic acid, which involves cutting out the modified amino acids and their subsequent re-synthesized replacement sites.This process is carried out in several stages.During postreplicative DNA repair in the structure of the molecule can be formed into a single gap value chain.Then they closed with the participation of the protein RecA.Postreplicative repair system is unique in that its process is no phase detection of pathogenic changes.
Who is responsible for the recovery mechanism
To date, scientists have known that such a simple creature, like E. coli, has at least fifty genes directly for repair.Each gene performs certain functions.These include: recognition, removal, synthesis, attachment, identification of the effects of UV exposure, and so forth.Unfortunately, any genes including those responsible for the repair processes in cells undergoing mutational changes.If this happens, they launch more frequent mutation in all cells of the body.
The risk of damage to DNA
Every day, the DNA of cells in our bodies are at risk of damage and pathological changes.It is promoted by environmental factors such as ultraviolet radiation, food additives, chemicals, temperature, magnetic fields, multiple stress, run certain processes in the body, and more.If the DNA structure is broken, it can cause a severe mutation in the cell, and in the future may lead to cancer.That is why the body is a complex of measures designed to deal with such injuries.Even if an enzyme is unable to return the original appearance to the DNA, the system operates on the repair, to reduce damage to a minimum.
Homologous recombination
will understand what it is.Recombination is the exchange of genetic material in the gap and connecting molecules of deoxyribonucleic acid.In the case where there are breaks in the DNA, the process of homologous recombination.During his two exchanged fragments of molecules.Thanks to this accurate restores the original structure of deoxyribonucleic acid.In some cases it may be DNA penetration.Through the process of recombination is possible to integrate these two disparate elements.
recovery mechanism and the health of the body
Reparation - it is a prerequisite of the normal functioning of the body.Being exposed to daily and hourly threatened damage and DNA mutations, multicellular structure adapts and survives.This is including the expense of established system of reparations.Lack of normal resilience causes diseases, mutations and other abnormalities.These include the development of various diseases, cancer, and even aging itself.Hereditary diseases due to violations of repair can lead to severe malignant tumors and other abnormalities of the body.Now identified some diseases caused by malfunctioning is DNA repair systems.These are, for example, pathologies, Cockayne syndrome, xeroderma, nonpolyposis colon cancer trihotiodistrofiya and some cancers.
