The structure of human DNA

The Existence of living matter is due to the presence of nucleic acids. F. Misher first identified these substances from the nuclei of leukocytes (1869). Later they were found in all cells of living organisms (people, animals, plants, bacteria and viruses).

Nucleic acid - prostatic group of the nucleoproteins. In the hydrolysis of nucleic acids get a nitrogenous base (adenine, cytosine, guanine, thymine and uracil), pentose (deoxyribose, ribose) and phosphate acid. Given the biochemical composition, nucleic acid klassificeret on deoxyribonucleic (DNA) and ribonucleic (RNA) acids. The structure of human DNA is deoxyribose, in the RNA is ribose. These acids differ in molecular structure, composition of nitrogen bases, the cellular localization and functions. Biomedicine, the molecule of which consists of a purine or pyrimidine base and a monosaccharide (ribose or desoxyribose) are called nucleosides. The name of the nucleoside is defined by the nitrogenous base that is contained in it. So, nucleoside, which consists of a molecule of adenine called adenosine, thymine - thymidine, uracil-uridine, cytosine - cytidine, guanine - guanosine. Depending on the monosaccharides (pentoses), which are part of molecules, there are ribonucleoside and deoxyribonucleoside.

Human DNA - the chemical basis of genes, in which is concentrated the hereditary information of an organism. Is localized mainly in the nuclei of cells, mainly the chromosomes. During the hydrolysis of DNA nucleotides are formed: deoxyadenylate (A), deoxyguanylate (G), deoxycytidylate (C) and Dimitrova (T) acid. Sometimes the composition of nucleotides found in small quantities other derivatives of purines and pyrimidines, minor bases: 5-oxymethyluracil (bacteriophages), 5-methylcytosine (in the tissues of the thymus), and others. The nucleotides together in the polynucleotide chain (DNA) oxygen bridges formed due to the hydroxyl residue of the acid phosphate of one nucleotide and the hydroxyl group at the third carbon atom of the remainder of desoxyribose of the second nucleotide.

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The Sequence of nucleotides in the DNA molecule of a person studying a sequencing method (eng. seguence - a study of the sequence). For this purpose, the device is a sequencer, which is based on computer analysis sets the sequence of nucleotides (up to one hundred units).

The Number of nucleotides in the molecule of human DNA is 25 000 - 35 000 and more, as molecular mass from a few million up to 2-5 billion DNA Molecules can “see” in the electron microscope. The absolute number of nucleotides of four kinds (A, G, C and T) in DNA molecules of different origin vary in wide ranges.

Primary structure of DNA

F. Crick and J. Watson in 1953 found that the molecule deoxyribonucleic acid is a double helix the polynucleotide chains coiled around its axis. The helix resembles a spiral staircase in which the handrail residues formed desoxyribose connected between a phosphoric ester bonds to 3 - 5 and level - nitrogenous bases. Adenine linked by hydrogen bonds with thymine, guanine with cytosine. Configuration of deoxyribonucleic acid can be compressed and stretched. This is the secondary structure of DNA. Some bacteriophages found spiral DNA molecule. For molecules of deoxyribonucleic acid characteristic tertiary structure, which is formed as a result of reunification and the double stranded circular DNA with subsequent formation of serialisierung and superspiralizatiou structures.