Metabolism consists of both material and energy metabolism. Metabolism is composed of two opposite and simultaneous processes, assimilation and anabolism. Assimilation and anabolism are both distinctly different and closely related. Without assimilation, the organism would not be able to produce new protoplasm and store energy, and anabolism would not be possible; on the contrary, without anabolism, there would be no energy release and the synthesis of substances in the organism would not be possible. It can be seen that assimilation and anisotropy are both opposed to each other and unified, and together they determine the existence and continuity of the organism. 2
During the long-term evolutionary process, organisms constantly interact with the environment in which they live and gradually develop different types of metabolism in the way they metabolise. According to the different processes of assimilation and alienation of organisms in nature, the basic types of metabolism can be divided into two types: assimilation and alienation. On the one hand, living organisms transform substances taken from the environment into their own substances through a series of chemical reactions. This process is called assimilation, i.e., the substance is transferred from the outside world to the body, from small molecules to large molecules. Thus, assimilation is a process of energy absorption, such as the use of photosynthesis by green plants to convert substances such as water and carbon dioxide in the environment into substances such as starch and cellulose. In contrast, isomerization is the process of changing substances from large molecules to small molecules from the body to the external environment, which is a process of releasing energy and expelling substances that the organism does not need or cannot use. 3
There is more than one metabolic pathway in the body, and the chemical reactions in the pathway are even more numerous and complex, and many metabolic processes even take place simultaneously in tiny cells, so suitable research methods are needed to track the metabolic processes. 4
1. Isotope tracing method
Isotopes are elements of the same type with the same atomic number but different atomic weights. When an atom in a compound molecule is replaced by an isotope ofthe same element, and the properties of the molecule remain unchanged after the replacement, it is called "isotopic labelling".
2. Enzyme inhibitor method and antagonist method
This method is commonly used for in vitro metabolic studies. Basically, all metabolic reactions are enzymatic reactions, so the metabolism of a substance in vivo can be inferred from the result of the inhibition of the reaction by blocking a certain part of the intermediate metabolism using an inhibitor or antimetabolite of an enzyme. Themetabolic function of an organ can be inferred by excising the organ of an animaland giving it a certain substance and observing the metabolic changes.
3. Use of subcellular components Centrifugation techniques such as ultracentrifugation, differential centrifugation, or density gradient centrifugation are used to separate various organelles within the cell, such as the nucleus, ribosomes, microsomes, and mitochondria, and then other methods are used to study the metabolic characteristics of subcellular components and the sites where various metabolic processes take place within the cell. 7
4. Methods of using normal organism
Perfusing, feeding or injecting a large amount of a certain metabolite into an animal and then analysing the intermediate or end products in the blood, tissues or excreta can help us to obtain information about the metabolism of substances in the body.