- What is catabolism?
- Differences between catabolism and anabolism
- Cell catabolism
- Muscle catabolism
- Importance of catabolism
- Catabolism example
We explain what catabolism is and its differences with anabolism. Also, the types that exist, importance and examples.
What is catabolism?
Catabolism is the process degradation of complex nutrients into simple substances to obtain energy for the organism. It is one of the two phases of metabolism of the living beings, the other being the anabolism (opposite and complementary process of catabolism).
This term comes from the Greek katos ("down") and ballein ("throw"), since it goes from the most complex and largest, to the simplest and smallest. It requires a small energy intake from the body but is released chemical energy that the body stores in the form of ATP (Adenosine Triphosphate) for use in other immediate processes.
Catabolic reactions, that is, those that make up catabolism, can be very different from each other, although at the same time they vary little between the various forms of life known. They generally consist of reduction-oxidation reactions of organic molecules, although there are microorganisms capable of metabolizing iron and sulfur.
Furthermore, catabolic reactions are divided into those that require oxygen (aerobic) and those that do not (anaerobic). Both occur in the organism of the human being, for example, as digestion proceeds (which breaks down the macromolecules organic compounds in their constitutive monomers) and then the intracellular metabolic cycle (Krebs cycle and oxidative phosphorylation).
Differences between catabolism and anabolism
Catabolism and anabolism are complementary but opposite processes. Catabolism breaks down organic macromolecules into simpler forms. Thus, it releases the chemical energy of its chemical links. Anabolism, on the other hand, consumes Energy of the organism to form new links and new molecules complex in the opposite direction.
Therefore, while one consumes energy, the other releases it; while one goes from the basic to the complex, the other goes in the opposite direction. This means that when catabolism and anabolism are in balance, the cells they remain stable; but when it is necessary to decompose tissues (such as "burning" fat), catabolism predominates over anabolism.
Cell catabolism
Catabolism takes place within the cells of the body through a series of processes that constitute cellular respiration. This occurs through different processes, depending on whether or not oxygen is present, but roughly it consists of the oxidation of glucose biomolecules for energy.
This process, called glycolysis, takes place in the cytosol of cells, obtaining for each molecule of glucose (with 6 atoms carbon) two pyruvate (with 3 carbon atoms each), in a process that reverses two ATP molecules to get four in return. Then, this pyruvate will be processed according to whether or not there is oxygen present in:
- Cellular respiration. In the presence of oxygen (aerobic environment) pyruvate is oxidized until obtaining CO2, releasing the energy of its bonds to make ATP with it. This occurs in the matrix of mitochondria of the cell in its first phase (the tricarboxylic acid cycle or the Krebs Cycle) and then in the respiratory chain that occurs in the mitochondrial membranes. This process is highly productive from an energy point of view and yields about 36 ATP molecules per glucose molecule.
- Fermentation cell phone. When oxygen is not present (anaerobic environment), organisms cannot oxidize pyruvate but ferment it, producing ethanol or lactic acid molecules instead of CO2. These molecules are much more difficult to remove and they perform much less energetically: only about 2 ATP molecules per glucose molecule.
Muscle catabolism
Muscle catabolism is called the reduction of muscle mass by the metabolism itself, that is, the destruction of muscle tissue to obtain the necessary resources to feed.
This occurs when food that enter the body are not enough to keep the metabolism going or when the energy demand is much higher than the amount of energy obtained from food.
In such cases, the body turns to body fat for additional energy to release and, once depleted, resorts to desperate measures such as "burning" the muscles to ensure that the metabolism keep going.
To avoid muscle catabolism, you must maintain a diet appropriate to the amount of exercise or physical activity performed. In addition, it is important to provide the body with sufficient opportunities for rest as the greatest amount of muscle mass is created during sleep.
Importance of catabolism
Catabolism is a key part of the metabolic process of living beings, that is, of their methods obtaining energy, especially in the case of heterotrophs, who must feed on the organic material of other living beings digesting it and breaking it down into minimal pieces useful for your body.
Understanding catabolism is essential to understand how and why we survive based on food consumption since our body must convert what we eat into useful pieces with which it must later compose new cells and new tissues.
Catabolism example
Catabolism is the basic principle behind the digestion of the food we consume. For example, the food we eat is processed and broken down into its biomolecules larger, which enter the body to be catabolized.
Thus, the protein are broken down into amino acids, lipids in fatty acids and sugars in monosaccharides. These simpler compounds then converge on the same metabolic pathway: Acetyl CoA, the compound that enters cells to initiate cellular respiration (Krebs cycle).