Biochemistry

CHAPTER 4. ENERGY PROCESSES IN THE ORGANISM 4.1 BIOLOGICAL OXIDATION Metabolism in living matter is impossible without the exchange of energy. In the process of life, organisms absorb energy from the environment in an adequate form for the given conditions, and then return its equivalent amount, but in a different form. It is known that the main carrier of energy is an electron (e'). Having received a certain amount of energy, it is excited: it goes to a higher energy level. Making the return journey to the lower orbit, the electron releases the same amount of energy. For all organisms living on Earth, the main source of energy is solar radiation. There are two groups of organisms that differ in the way they eat - autotrophs and heterotrophs . Autotrophs (green plants) are able to directly capture solar energy and use it to create organic compounds. Heterotrophs are organisms that assimilate ready-made organic substances that have a certain potential energy reserve. In the process of their life during biological oxidation, energy is released . The great artist, scientist and naturalist of the Renaissance, Leonardo da Vinci wrote: "Life is possible where fire can bum". In other words, life processes are carried out only in the presence of energy obtained during oxidation. Even in antiquity, it was known that coal or wood, when burned, emit thermal energy, and this requires air. M.V.Lomonosov for the first time in 1756 showed that when calcined in air, metals increase in mass. From this it was concluded that the air joins the metals. The results of the experiments of MV Lomonosov refuted the theory of phlogiston (from the Greek. Phlogistos - flammable). According to the idea of chemists of the late XVII - early XVIII centuries, phlogiston is “ the beginning of combustibility ” , a hypothetical component of the substance that they allegedly lose during combustion and firing. About 20 years later, in 1774, the French chemist A.Lavoisier proved that the same products — CO 2 and H 2 O are formed during the combustion of organic matter in and outside the body, and in both cases heat is released. This fact was important not only for studying the mechanisms of energy release in the body, but also methodologically, since the unity of the processes occurring in animate and inanimate nature was proved. In living organisms, the energy released during oxidation is stored mainly in the form of chemical energy, which after use passes into heat. 102