If we imagine the appearance of the DNA molecule, it resembles a twisted helix, which is formed by two polynucleotide chains that are twisted together and at the same time around one of their common axes.
As a rule, the structure of DNA is considered in the framework of systems analysis, at the same time as the main - it is strictly established (for normal condition) order interposition dezoksiribonukleozidmonofosfatov - dNMP, constituting the polynucleotide chain.
in unmutated cells mononucleotides joined phosphodiester bonds, thus, the end of the polynucleotide chain themselves have two options for the location of the real groups in the 5'-end of the chain is the phosphate group and the OH group is in the Z'-end chain.
If we consider a molecule consisting of two chains, the structure of DNA is such that the polynucleotide chain will be antiparallel to each other.When the retaining circuit, in such a structure will be due to the hydrogen bonds which exist between the bases A and T GC, lying in the same plane perpendicular to the main axis of the helix molecule.Those hydrophobic interactions, which are formed between the bases of such molecules provide the stability of the double helix.For such a molecule, the structure is characterized by DNA complementary polynucleotide chains, but their identity as their base composition varies.
Further, considering what the structure of DNA, it should be noted that each individual molecule is "packed" in a strictly unique, individual chromosomes.These chromosomes contain a variety of proteins, which correspond to well-defined sequences of the structure of the DNA molecule.These proteins are classified into two categories: histones and proteins negistony.Combined with the nuclear DNA of these proteins is called chromatin.
Describing the structure of DNA, it should be noted that chromatin consists of five types of histones, the total positive charge which provides a very strong bond histones with DNA.The complex of histones and DNA molecules of a certain area, encompassing 146 base pairs, is reacted, in which nucleosomes are formed.
Included in the structure of the DNA molecule proteins negistony represent various types of regulatory proteins associated with certain DNA sequences.Also, the structure of the DNA molecule complementary enzymes providing biosynthesis.
investigate the structure of DNA and RNA within the system analysis should be only in the complex, that is, when considering the structure of DNA, must be considered and the structure of RNA.
Its primary structure, as in the case of a DNA molecule is an interleaving algorithm ribonukleozidmonofosfatov, thus, be aware that, in contrast to DNA molecules, all types have only one RNA polynucleotide chain.In the structure of the RNA molecule, its individual chains formed by the so-called "stud" - helical loops which are the bases of AU and GC and stabilized by hydrogen bonds.
Typically, the average value of the DNA molecule comprises 150 million base pairs, and its length is four centimeters.In the laboratory analysis of these molecules is extremely inconvenient for the study, because when it is isolated from the tissues, a molecule tends to be highly fragmented and become much smaller in size.To eliminate this inconvenience, in the studies used PCR - polymerase chain reaction, in which the election takes place synthesizing individual sections of the DNA molecule, and to allocate the necessary studies for the fragments.
