I group. The main components of all organic compounds that perform biological functions are oxygen, carbon, hydrogen and nitrogen. All carbohydrates and lipids contain hydrogen, carbon and oxygen, and the composition of proteins and nucleic acids, in addition to these components, includes nitrogen. These four elements account for 98% of the mass of living cells.
II group. Phosphorus, sulfur, potassium, magnesium, sodium, calcium, iron, and chlorine also belong to the macroelement group. These chemical elements are essential components of all living organisms. The content of each of them in the cell is from tenths to hundredths of a percent of the total mass. Sodium, potassium and chlorine provide the emergence and conduct of electrical impulses in the nervous tissue. Maintaining a normal heart rate depends on the concentration of sodium, potassium and calcium in the body. Iron is involved in the biosynthesis of chlorophyll, is part of hemoglobin (a protein that carries oxygen in the blood) and myoglobin (a protein that contains oxygen in muscles). Magnesium in plant cells is part of chlorophyll, and in the animal body is involved in the formation of enzymes necessary for the normal functioning of muscle, nervous and bone tissues. Protein often contains sulfur, and all nucleic acids contain phosphorus. Phosphorus is also a component of all membrane structures. Among both groups of macrocells, oxygen, carbon, hydrogen, nitrogen, phosphorus and sulfur are combined into a group of bioelements, or organogens, on the basis that they form the basis of most organic molecules.