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Why is the Krebs cycle called the "heart of life"? How does this cycle affect our cells?
The Krebs cycle, also known as the citric acid cycle or the tricarboxylic acid cycle, is a series of important biochemical reactions within cells that are primarily designed to release energy stored in nutrients. This cycle works by oxidizing acetyl-CoA produced from sources such as carbohydrates, fats, proteins, etc., and ultimately producing ATP, which provides the cells with the energy they need. Therefore, the Krebs cycle is known as the "heart of life."
The Krebs cycle converts nutrients into usable chemical energy, which allows cells to perform a variety of functions necessary for life.
The importance of this cycle is that it is not only a supplier of energy, but also provides the precursor of some amino acids and the reducing agent NADH, which play a vital role in many other reactions. The involvement of the Krebs cycle makes it a core component of many biochemical pathways, which also indicates that it is one of the important components in the early stages of metabolism.
Basic process of Krebs cycle
The Krebs cycle begins when acetyl-CoA combines with four-carbon oxaloacetate to form six-carbon citrate. Next, the citric acid undergoes a series of chemical changes to release two molecules of carbon dioxide (CO2). These carbon atoms come from oxalamide rather than directly from acetyl-CoA. During the entire process, the reducing substances NADH and FADH2 produced are further involved in the generation of energy.
At the end of this cycle, oxalamide is regenerated again, allowing the cycle to continue.
Each acetyl group that enters the Krebs cycle produces three NADH, one FADH2, and one GTP. These products are eventually converted into ATP and used in various cellular activities. For each pyruvate molecule from glycolysis, the number of energy products obtained from the Krebs cycle amounts to three NADH, two FADH2, and four carbon dioxide molecules.
Historical background of the Krebs cycle
The discovery of the Krebs cycle can be traced back to the 1930s, by the famous biochemists Albert Szent-Györgyi and Hans Adolf The research by Krebs et al. provided the basis for the composition and reactions of this cycle. Krebs won the Nobel Prize in 1953 for his contributions to physiology and medicine.
The impact of Krebs cycle on cells
After acetyl-CoA produced from the metabolism of carbohydrates, fats, and proteins enters the Krebs cycle, its energy is effectively utilized and converted into ATP. This is not only an important process in physiology, but also closely related to the health and function of cells. During aerobic and anaerobic respiration, the energy released by the Krebs cycle will support cell growth and reproduction.
The regulation of the Krebs cycle is related to the concentration of its products. When NADH production is too high, it inhibits many important enzymes, reducing the efficiency of this cycle. In addition, changes in calcium concentration will also affect this cycle. Calcium can activate multiple links and increase the metabolic rate.
As gravity advances, the regulation and rate of this cycle dynamically changes in the cell's metabolism to adapt to changes in energy demand.
Future research directions
With the development of biomedicine, the role of Krebs cycle in diseases, especially cancer, has become increasingly important. In many tumor cells, Krebs cycle intermediates are used to promote cancer cell proliferation. So studying how this cycle changes might lead to new treatments for new tumors.
To sum up, the Krebs cycle, as the heart of life, not only plays an important role in physiology, but also plays a key role in the maintenance of cellular health and the formation of disease mechanisms. Can we further decipher the implications of this cycle for future health?
