In blood the amount of glucose is supported at rather constant level (about 0,11%). Reduction of the content of glucose causes fall of temperature of a body, disorder of activity of nervous system, exhaustion. Increase of amount of glucose causes its adjournment in a liver in the form of spare animal starch – a glycogen. Value of glucose for an organism is not settled by its role as power source. Glucose is a part of cytoplasm and is therefore necessary at formation of new cages, especially during growth.
Fat is used by an organism as a rich power source. At disintegration of one gram of fat in an organism it is released energy twice bigger, than at disintegration of the same amount of proteins and carbohydrates. Fats are and a part of cages (cytoplasm, a kernel, cellular membranes) where their quantity is steady and constant.
Through plastic and power exchanges communication of a cage with environment is carried out. These processes are the main condition of maintenance of life of a cage, a source of its growth, development and functioning.
The second function of a metabolism – providing a cage with energy. Any manifestation of activity (the movement, biosynthesis of substances, generation it is warm, etc.) need energy expense. For power supply of a cage energy of chemical reactions which is released as a result of splitting of the arriving substances is used. This energy will be transformed to other types of energy. Set of the reactions providing cages with energy is called a power exchange.
Sounds nicely, isn't that so? Especially, if to consider that copies have to be live and be thus in such conditions that at least did not spoil. Imagine these "warehouses" of live human "spare parts"?
The DNA main function – information: an order of an arrangement of its four nucleotides (a nucleotide - monomer; monomer – the substance consisting from repeating elementary links bears important information – defines an order of an arrangement of amino acids in linear molecules of proteins, i.e. their primary structure. A set of proteins (enzymes, a hormone defines properties of a cage and an organism. Molecules of DNA store data on these properties and transfer them to generations of descendants, i.e. DNA is the carrier of hereditary information.
Carbohydrates are important and in a metabolism of the central nervous system. At sharp decrease in amount of sugar in blood disorders of activity of nervous system are noted. There come spasms, nonsense, loss of consciousness, change of action of the heart.
Proteins are a part of cytoplasm, hemoglobin, plasma of blood, many hormones, immune bodies, maintain constancy of the water-salt environment of an organism. Without proteins there is no growth. The enzymes which are surely participating in all stages of a metabolism have the proteinaceous nature.