The established ideas about the genetic code are considered, taking into account the achievements of scientists of the previous period. The shortcomings and contradictions of these ideas are noted, which are mainly related to the assumption of the three-dimensionality of biomolecules and the linearity of nucleic acids. Since in recent years it has been clearly shown that these assumptions are far from reality, a new concept of the genetic code has been put forward, considering the higher dimension of sugar molecules, phosphoric acid residues and nucleic acids. It is shown that nitrogenous bases are located in two-dimensional coordinate planes of the polytope of hereditary information, and the number of these coordinate planes is exactly equal to the number of possible types of amino acids, i.e., each coordinate plane corresponds to some amino acid.
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The covalent structure of purines and pyrimidines, as well as nucleotides included in the polytope of hereditary information, undergo spontaneous changes. Changes in the structure of DNA that leads to permanent changes in the genetic information encoded in it are called mutations. There are numerous data that testify in favor of the existence of a close relationship between the accumulation of mutations in the body and the processes of aging and carcinogenesis (Golubev, 2015). Virtually all life forms are exposed to high-energy radiation that can cause chemical changes in DNA (Nelson, Cox, 2022, V.2). It is known that radiation with wavelengths from 200 to 400 nm (UV), which makes up a significant part of the solar spectrum, can cause the formation of pyrimidine dimers and other chemical changes in DNA. We are under the constant influence of ionizing radiation in the form of cosmic rays, which can penetrate deep into the earth, as well as radiation coming from radioactive elements such as radium, pluton, uranium, radon. X-rays, used in medical and dental examinations and in radiation therapy for cancer and other diseases, are another form of ionizing radiation (Melekhova, 2010; Polesskay, 2007).
Free radical reactions that ensure the respiration of organisms (Nelson, Cox, 2022) are accompanied by the generation of reactive oxygen species (ROS), which can initiate chain free radical processes that have a permanent destructive effect on cells. This action is enhanced by unfavorable environmental factors that cause oxidative stress in cells, which is accompanied by membrane destruction due to lipid peroxidation (Melekhova, 2010; Schaich, 2005).
DNA can also be damaged by chemically active substances released into the environment from industrial waste. These substances are able to change certain DNA bases. The most important source of mutations is oxidative damage to DNA. Reactive oxygen species - hydrogen peroxide, hydroxyl radicals and superoxide radicals - are formed under the action of radiation or as by-products of aerobic metabolism (Polesskay, 2007). These compounds can damage DNA in any of the many reactions that make up a large and complex group: from the oxidation of deoxyribose residues and nitrogen bases to chain scission. Cells have a fairly developed defense system against reactive oxygen species; however, some oxidizing agents bypass this defense system. Repair systems significantly reduce the extent of DNA damage. Some nucleotide bases in the DNA molecule are enzymatically methylated. Methylation is usually limited to certain sequences or regions of DNA. In some cases, the function of methylation is well understood, while in others its functional significance remains unclear. There are two main systems that provide DNA methylation. One of them serves as part of a defense mechanism that allows the cell to distinguish its own DNA from foreign by its own DNA with methyl groups and the destruction of foreign DNA that does not contain methyl groups. Another system methylates adenosine residues. The addition of methyl groups is carried out by the methylase component of the system, which corrects mismatched pairs of nitrogenous bases (Nelson, Cox, 2022, V.3).