The set of cleavage reactions is called cell energy metabolism or dissimilation. Dissimilation is the exact opposite of assimilation: as a result of splitting, substances lose their resemblance to cell substances.
Energy metabolism is usually divided into 3 stages. The first stage is preparatory. At this stage, the molecules of di- and polysaccharides, fats, and proteins break down into small molecules – glucose, glycerin and fatty acids, amino acids, large nucleic acid molecules – into nitrogenous bases – nucleotides. At this stage, a small amount of energy is released, which is dissipated as thermal energy.
The second stage is anoxic or incomplete. It is also called anaerobic respiration or fermentation. The term “fermentation” is usually used in relation to processes occurring in the cell of microorganisms or plants. The substances formed at this stage with the participation of enzymes enter the path of further cleavage. In muscles, for example, as a result of anaerobic respiration, a glucose molecule breaks down into 2 lactic acid molecules (glycolysis). Phosphoric acid and ADP are involved in glucose breakdown reactions.
The third stage of energy metabolism is the stage of aerobic respiration, or oxygen breakdown. The reactions of this stage of energy metabolism are also catalyzed by enzymes. When O reaches the cell, the substances formed during the previous stage are oxidized to the final products — H2O and CO2. oxygen breathing is accompanied by the release of a large amount of energy and its accumulation in ATP molecules.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.