Biochemistry

A variety of functional groups can be firmly “ attached ” to the carbon “ skeleton ” , creating an inexhaustible wealth of organic compounds. The diversity of carbon compounds corresponds to the diversity of life forms on Earth. That is why carbon, being a part of all organic compounds, plays a unique role as the most important element of living matter. Oxygen is 47% of the mass of the hard shell of our planet. Even more in the hydrosphere - the water shell of the Earth (86%). In an oxygen atmosphere, about 20% by volume (about 10 15 tons). Most chemical elements exist in nature in the form of oxygen-containing compounds. These include all the most important bioorganic compounds (proteins and nucleic acids, lipids, carbohydrates, enzymes, vitamins, etc.), as well as water. All free (molecular) oxygen is a product of photosynthesis, that is, it has a biogenic origin. Oxygen is widely distributed in animate and inanimate nature, mainly because it is a strong oxidizing agent that forms oxides with most metals and non-metals. In biological environments, oxygen plays an indispensable physiological role', its reaction with many biomolecules, primarily with carbohydrates and lipids, serves as an energy source for the body. Nitrogen is one of the most common elements, the main component of the Earth ’ s atmosphere (78% by volume or 4-1 0 1 8 tons). Nitrogen as an indispensable chemical element is part of such important bioorganic compounds as amino acids and proteins, nitrogenous bases and nucleic acids, vitamins, etc. Therefore, it is no accident that nitrogen is often called the "element of life." Indeed, the development of any organism requires a constant influx of nitrogen-containing compounds from the external environment in an easily digestible form. However, the vast majority of organisms are not able to assimilate molecular nitrogen (N2), and therefore, an almost inexhaustible supply of nitrogen in the atmosphere is not available to them. Hydrogen is the most common element of the universe. On Earth, hydrogen, including water and air, accounts for about 1% by weight. Hydrogen is a very common and vital element, since it is part of all bioorganic compounds, as well as the most common substance on Earth - water. Not only a variety of hydrogen compounds, but also molecular hydrogen (H 2 ) itself is the basis for the existence of some organisms. In biological media, hydrogen is usually present either in the form of a cation (If) or in the form of compounds with biogenic elements (C, O, N, S). In the this case, the degree of polarity of the “ element - hydrogen ” bond determines the most important properties of such compounds. 8