What is Catabolism?

Metabolism is a general term for a series of ordered chemical reactions that take place in an organism to sustain life. These reaction processes enable organisms to grow and reproduce, maintain their structure, and respond to the external environment. Metabolism is usually divided into two categories: catabolism can break down large molecules to obtain energy (such as cellular respiration); anabolic metabolism can use energy to synthesize various components in cells, such as proteins and nucleic acids. Metabolism can be thought of as the process of constant exchange of matter and energy by the organism. Once the exchange of matter and energy stops, the structure of the organism will disintegrate. Metabolism is also called cell metabolism.

A general term for various chemical reactions occurring in cells, which are mainly composed of two processes, catabolic and anabolic.

The concept of metabolism

Metabolism is all orderly in the body

Metabolism is a constant activity in the body without awareness, including

The scientific research on metabolism has spanned centuries, from the early studies of animal metabolism to the exploration of single metabolic response mechanisms in modern biochemistry. The emergence of the concept of metabolism dates back to the 13th century. Arab medical scientists

Most of the constituent structures of animals and plants and microorganisms are composed of three types of basic biological molecules. These three types of molecules are

Catabolism (also known as alienation) is a general term for a series of reaction processes that lyse macromolecules, including cleavage and oxidation of food molecules.

Anabolic (also known as assimilation) is a general term for a series of anabolic processes (that is, the use of energy released by catabolism to synthesize complex molecules). Generally speaking, for composition

Metabolic oxidative phosphorylation

Structure of ATP synthase. Its proton channels and axis of rotation are shown in blue, synthase subunits are shown in red, and fixed subunits are shown in yellow. In oxidative phosphorylation, through metabolic pathways such as the citric acid cycle, electrons are transferred from digested and absorbed food molecules to oxygen, and the energy produced is stored in the form of ATP. In eukaryotes, this process is accomplished by a series of membrane proteins located on the mitochondrial membrane, called the electron transfer chain. In prokaryotes, the corresponding protein is located on the inner membrane of the cell. [These proteins use energy generated by reactions that pass from electron-reducing molecules such as NADH to oxygen to transport protons across the membrane. As a result of pumping protons out of the mitochondria, a difference in the concentration of protons is generated on both sides of the mitochondrial membrane, thereby forming an electrochemical gradient on both sides of the membrane. The driving force generated by the electrochemical gradient causes the protons to re-enter the mitochondria through the ATP synthase on the mitochondrial membrane. Such a proton flow will cause the stalk subunit of ATP synthetase to rotate, and further drive the active site on the synthetase domain to deform and phosphorylate adenosine diphosphate (ADP), eventually producing ATP

Metabolizes energy from inorganic matter

Chemoenergy inorganic nutrition is a type of metabolism found in some prokaryotes. These prokaryotes obtain energy by oxidizing inorganic substances. They can use hydrogen, reducing sulfur compounds (such as sulfides, hydrogen sulfides, and thiosulfates), divalent iron compounds [or ammonia] as a source of reducing energy; the electron acceptors of the oxidizing processes of these reducing substances are often For oxygen or nitrite. These processes are important for the overall biogeochemical cycle, such as acetogenesis and nitrification and denitrification, and are critical to soil fertility.

Metabolizes energy from light

The energy in sunlight can be captured by plants, cyanobacteria, purple bacteria, green bacteria and some protists. This process of capturing light energy is often coupled with the conversion of carbon dioxide into organic matter (ie, "carbon fixation") and becomes part of photosynthesis. Light energy harvesting and carbon fixation systems can operate separately in prokaryotes, because purple bacteria and green bacteria can use sunlight as a source of energy whether they are carbon-fixed or when organic matter is hydrolyzed.

The process of capturing solar energy is essentially similar to oxidative phosphorylation, because both include the existence of energy in the form of a proton concentration gradient and the synthesis of ATP driven by this concentration difference. [The electrons used to drive the electron transport chain are from light-harvesting proteins called photosynthetic reaction centers. According to the type of photosynthetic pigments contained, the reaction center can be divided into two types: demagnesium chlorophyll-quinone and iron-sulfur type; most photosynthetic bacteria contain only one type of reaction center, while plants and cyanobacteria Contains two types.

In addition, the photosystem is a protein complex that plays a major role in photosynthesis, including photosystems I and II. In plants, Photosystem II can use light energy to obtain electrons from water and release oxygen. The electrons then flow into the cytochrome b6f complex, which uses energy to pump protons out of the thylakoid (located in the chloroplast) membrane. The pumped protons return to the thylakoid through the membrane, driving ATP synthesis (similar to ATP synthesis in oxidative phosphorylation). As electrons continue to flow through Photosystem I, they can be used to reduce the coenzyme NADP +, used in the Calvin cycle, or recovered to synthesize more ATP.