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    Home > Biochemistry News > Biotechnology News > DNA doesn't break down for decades after a person dies?

    DNA doesn't break down for decades after a person dies?

    • Last Update: 2020-08-10
    • Source: Internet
    • Author: User
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    DNA doesn't break down for decades after a person dies? The police cut out the victims or suspects who had been dead for decades, and the fatty proteins were broken down, but the dna could be extracted.
    : Because DNA is a genetic material, its physical and chemical properties are relatively stable.
    , other substances that make up the human body, such as protein, fat, carbohydrate (sugar) can be used as a source of energy for microorganisms, decomposition and utilization is less difficult.
    DNA, or deoxyribonucleic acid, consists of four different bases, namely adenine (A), thymus (T), cytosine (C), and ostrich (G).
    the chemical structure of thymus and cytosine, which are six-dollar rings containing two nitrogen atoms, which can be collectively referred to as diazepam, which are flat molecules, similar to benzene rings. C and N on the
    ring are sp2 hybridized orbits, each atom has an electron in the p-orbit that is not involved in hybridization, the side overlaps to form a large bar, and the two nitrogen atoms each have a pair of unshared electron pairs left in the sp2 hybrid orbit.
    such chemical structure determines that the chemical properties of radon have the following characteristics - (1) hydroelectric substitution is difficult to occur, including nitrification and sulfonization reactions (2) the chemical structure of adenine and ostrich, respectively, are not easily oxidized, as a hybrid aromatic organic compound with four nitrogen atoms, its chemical properties are also relatively stable.
    adenine, thymus, cytosine and ostrich, the four molecules that make up DNA are more physically and chemically stable on the one hand, and on the other hand, it is difficult for microorganisms to use these substances as a source of energy, in the presence of large amounts of fat and protein, these substances will not be prioritized decomposition.
    on the other hand, DNA has a double helix structure, the base pairs of the two chains will form a complementary pair through the hydrogen bonds, adenine and thymus can form two hydrogen bonds between the bird and cytosine can form three hydrogen bonds.
    as above, the union with each other in the form of base pairing greatly improves the overall stability of DNA, the hydrophobic effect of polar molecule formation in DNA also helps the stability of DNA, in addition, the above-mentioned non-involved sp2 hybridized p-orbit electron side overlap formation of large slug bonds in the DNA will form an overlapping (Stacking), which can further enhance the stability of the molecular structure.
    DNA degrades slowly under natural conditions, with a half-life of approximately 521 years (Reference: Matt Kaplan, DNA has a 521-year half-life. Nature doi: 10.1038/nature.2012.11555), the problem says dna extraction is entirely possible decades later.
    DNA can be extracted even in burning in low-temperature remains, showing the strong stability of DNA.
    : This contains two main questions, one is what is broken down after death and why DNA is preserved for a long time.
    let's look at these two aspects separately.
    first, what is broken down after death, that is, what causes the body to become corrupt after death.
    the essence of corruption is that proteins are degraded by bacteria, after death, the immune system function is lost, a variety of bacteria began to grow, the resulting protein hydrolysis enzymes to the body protein decomposition.
    proteins are broken down into organic and inorganic matter, such as ketoacids, methane, methylpyridoxiin, fecal skunk, methamido-amine, carcass and so on.
    inorganic substances such as ammonia.
    these substances can make the body smell bad.
    , microorganisms break down the body's adipose tissue: First, the fat enzyme produced by bacteria breaks down fat, producing free fatty acids and glycerin;
    second, why DNA is preserved for a long time.
    DNA is genetic material, genetic material as an important material to save life information, the body has various mechanisms to ensure the stability of DNA.
    first, DNA is a double-stranded structure, relying on hydrogen bonds and base accumulation forces to maintain its stability;
    Answer 3: The chemical properties of DNA are relatively stable, DNA molecules are difficult to deactat, unless in nuclease and high temperature seismostaly, this is the reason why DNA is used for identification, there is also the chromosome DNA is a billion base pairs composed of macromolecules, so the explanation express is certainly slow, slowly than fat proteins remember attention - DNA is a double helix structure, is a deoxygenation structure Ribonucleic acid and a molecule containing nitrogen base, a molecule of DNA, a molecule of phosphoric acid composition, DNA has four bases, adenine, thymus, cytosine, bird, they are arranged in different order, high school creatures should say, I remember, I also back, DNA is the basis of genetic material, there are C H O N P species elements.
    stability so not to be decomposed is this kind of stability, DNA in the investigation field, medical identification community set up a sweat horse credit, many people do paternity identification is to do DNA, paternity identification with DNA fingerprints, look at the overlap of two people's DNA, with a high degree of variability and stable heredity, widely used for paternity identification.
    : Not because of how stable the structure of the DNA is, but because the proteins that make up the bones and hair are stable.
    bones have many bone cells, and the DNA in the nucleus is preserved by the protection of the protein on the outside.
    a piece of raw meat, animals are very easy to digest, to digest the bones not chewed is not necessarily.
    a piece of raw meat, buried in wet soil for three years, must not find DNA, bacteria, fungi and other microorganisms must have a way to digest all raw meat, including DNA. Microbes will turn raw meat into CO2, H2O, urea, uric acid, ammonium salts, nitrates, anti-nitrification bacteria will nitride into nitrogen, return to nature.
    so, if buried in the soil for three years of broken bodies, only meat, only internal organs, can not find bones, hair, want to find DNA, it is impossible.
    Source: Today's Headlines.
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