Cellular respiration
Cellular respiration is a vital biochemical process by which living organisms convert the chemical energy stored in food into usable energy in the form of Adenosine Triphosphate (ATP). This process primarily utilizes glucose as its energy source, but carbohydrates, fats, and proteins can also be metabolized. Cellular respiration involves three main stages: glycolysis, the Krebs cycle, and the electron transport chain. Glycolysis occurs in the cytosol, breaking down glucose into pyruvate and producing a small amount of ATP and NADH. The Krebs cycle then takes place in the mitochondria's matrix, where the pyruvate further breaks down, resulting in additional ATP and electron carriers.
The final stage, the electron transport chain, occurs in the inner mitochondrial membrane and generates the majority of ATP through oxidative phosphorylation. While aerobic respiration, which requires oxygen, can yield up to 38 ATP molecules per glucose molecule, anaerobic respiration can only produce about 2 ATP molecules, relying on glycolysis and fermentation when oxygen is not available. Overall, cellular respiration is essential for energy production in both aerobic and anaerobic organisms, reflecting the intricate biochemical networks that sustain life.
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Cellular respiration
Cellular respiration is the name of the process or processes involved when chemical energy from food is translated into energy in the form of Adenosine Triphosphate, abbreviated as ATP. Most food substances undergo changes through cellular respiration, notably carbohydrates, fats, and proteins; however, the main energy supply derives from the transfer of energy via glucose. There are three primary steps pertaining to the process: glycolysis, the Krebs cycle, and the electronic transport chain. Collectively, this is called cellular respiration and requires the intake of oxygen for the chemical reaction to be complete. Without oxygen, cellular respiration may occur, but only as glycolysis and fermentation in the cytosol region. The equation for cellular respiration is C6 H12 06(glucose) + 6 02(oxygen) -> 6 CO2(carbon dioxide) + 6 H20 (water)+ Energy (ATP). Aerobic or anaerobic respiration are two routes wherein cellular respiration can occur.
Background
Glycolysis, the Krebs cycle, and the electronic transport chain are metabolic processes. The location in which these occurrences or cycles take place is within a particular part of the cell. The first aspect of the procedure is glycolysis occurring in the cytosol. The process then moves into the matrix of the mitochondria where the Krebs cycle comes into action. Finally, the electron transport chain happens in the inner mitochondrial membrane. In order for cellular respiration to take place, the presence of oxygen is necessitated. Carbon dioxide may be released in the process.
Although both aerobic and anaerobic respiration involve glycolysis, they diverge at this point, traversing different routes to produce energy. Aerobic respiration is a complex biochemical system with a higher efficiency level of energy production than its anaerobic counterpart. Anaerobic respiration has the ability to function even when there is no oxygen; this may happen when oxygen is either not present or when the muscles have tired and have used up their oxygen supply. Given that glycolysis does not require oxygen, anaerobic respiration and glycolysis are able to converge, but thereafter, as nicotinamide adenine dinucleotide (NAD+) is needed, fermentation may kick into place to supply NAD+. Alternatively, aerobic respiration is required as one of the functions of the electron transport chain is to turn nicotinamide adenine dinucleotide (NADH, the reduced form) back into NAD+ by utilizing oxygen.
Cells, cytosol and cytoplasm; mitochondria, matrix, and inner mitochondrial membrane: The cell is the fundamental part of the living human body. Cells may be prokaryotic or eukaryotic, comprising pre-nucleus stage or possessing a nucleus, respectively. Cytosol is the intra-cellular fluid inside cells. Cytoplasm is the protoplasm of the cell, without the nucleus. The mitochondrion is an organelle in a eukaryotic cell and is located within the cytoplasm of the cell. The inner membrane of the mitochondria is considered to be the power centers of the cell. The matrix of the mitochondria is the innermost central substance where the cells are embedded. Cellular respiration occurs in these essential sections of the living body cells.
Overview
Cellular respiration commences with glucose, without which it would not occur. When the glucose is broken down during glycolysis and pyruvate is produced, this sets into motion a stream of actions and reactions controlled by enzymes to motivate the synthesis of ATP.
Glycolysis.The chemical process of glycolysis pertains to the breaking down of glucose, a sugar, from a six-carbon ring to two three-carbon molecules. The latter is called pyruvate and may further be referred to as pyruvic acids or pyruvic molecules. When this occurs, ATPs are created. There are ten enzymatic reactions that happen in order to change the structure of the glucose. When the carbon rings are split into two pyruvic acid molecules, that action generates two molecules of ATP as a net gain. In addition, two nicotinamide adenine dinucleotide (NADH) molecules are formed.
Krebs Cycle.The Krebs cycle is named after Sir Hans Krebs who discovered the reactions during the 1930s. The Krebs cycle is also referred to as the citric acid or tricarboxylic acid cycle. The inner membrane of the mitochondria is the power center of the Krebs cycle stage of cellular respiration. Here, the products that have been formed during glycolysis undergo more chemical changes. The rich carbon molecules of pyruvate are transformed, and an additional two ATP molecules are formed per each glucose molecule. There is a complex adaptation of products that result in the new source of chemical energy supply. As pyruvate enters the mitochondria, it loses carbon dioxide and forms a two-carbon molecule entitled acetyl-CoA. During the Krebs cycle, acetyl-CoA becomes oxidized. NADH, FADH2 and ATP are released as energy. Two ATP molecules are made during the Krebs cycle, in addition to the two produced during glycolysis.
Electron Transport Chain.The third and final process of cellular respiration is oxidative phosphorylation, commonly referred to as the electron transport chain. This produces the largest amount of energy and its release. Oxidative phosphorylation is conducted in the inner mitochondrial membrane. NAD+ and FAD (Flavin adenine dinucleotide) accept electrons and transport them to the mitochondria where they transform into NADH and FADH2. Water, or H2O, is formed during the electron transport chain. At the time of the final process, the largest amount of ATP is manufactured. These thirty-four ATP molecules are added to the two formed during glycolysis and the two of the Krebs cycle, totaling thirty-eight.
Fermentation.Fermentation refers to the production of ATP when oxygen is not present. Oxidization of NADH from glycolysis results in a regeneration of NAD+. Glycolysis is restarted, and ATP is manifested.
Aerobic respiration generates a high level of ATP molecules. Thirty-six to thirty-eight ATP molecules are created from each glucose molecule during aerobic respiration and the presence of oxygen. By contrast, anaerobic cellular respiration produces only two ATP molecules, in the absence of oxygen. The latter occurs via glycolysis and fermentation.
Bibliography
"Aerobic and Anaerobic Respiration." BBC, www.bbc.co.uk/bitesize/articles/zcsbmsg. Accessed 7 Aug. 2024.
"Cellular Respiration." National Geographic, education.nationalgeographic.org/resource/cellular-respiration-infographic/. Accessed 7 Aug. 2024.
Wolfe, Ernest. "3 Simple Stages in Cellular Respiration and How They Work." Medium, 14 Nov. 2016, medium.com/countdown-education/3-simple-stages-in-cellular-respiration-and-how-they-work-4de3abc5f819. Accessed 7 Aug. 2024.