### select reactions that occur during the second stage of glycolysis

In comparison, automobiles are only about 20%–25% efficient in using the energy released by the combustion of gasoline. One pyruvate has 3 carbons; There are 2 pyruvates in every glucose molecule; 2. Therefore, 3-phosphoglycerate is rearranged in the presence of phosphoglycerate mutase and it’s metal ion co-factor, Magnesium, which leads to yield the product. 1,3\textrm{-bisphosphoglycerate} + NADH}\), $$\mathrm{3\textrm{-phosphoglycerate} \xrightarrow{phosphoglyceromutase} \, ? (3) transfer of a hydride ion to NAD, forming NADH. In many of these people, the disease can be controlled with a combination of diet and exercise alone. 5. 2. The phosphate group of PEP is transferred to ADP, with one molecule of ATP being produced per molecule of PEP. However, in the absence of oxygen (that is, under anaerobic conditions), the fate of pyruvate is different in different organisms. The reaction is facilitated with the help of an enzyme which is known as pyruvate kinase. Researchers are still trying to find out why. In this reaction, oxidative phosphorylation is joined to electron transport, so it is known as respiratory-chain phosphorylation. Thus, the preparatory phase of glycolysis came to an end due to this reaction and this very step. The first stage of cellular respiration, glycolysis, takes place in the cytoplasm of the cell. The transfer of intermediates from one enzyme to the next occurs by diffusion. Where does lactic acid fermentation occur in cells? The enzyme that catalyzes the reaction is, In the next reaction, the phosphate group on 3-phosphoglycerate is transferred from the OH group of C3 to the OH group of C2, forming 2-phosphoglycerate in a reaction catalyzed by, The final step is irreversible and is the second reaction in which substrate-level phosphorylation occurs. b. occurs only in animal cells because plants carry on photosynthesis. e. is the only cellular mechanism that yields ATP. In the reaction of this step, in the reaction, the inter-molecular shift of 3-phosphoglycerate happens. From the reactions in Exercises 1 and 2, select the equation(s) by number and letter in which each type of reaction occurs. The first phase is the energy-consuming phase, so it requires two ATP molecules to start the reaction for each molecule of glucose.However, the end of the reaction produces four ATPs, resulting in a net gain of two ATP energy molecules. \xrightarrow{phosphoglucose\: isomerase} fructose\: 6\textrm{-phosphate}}$$, $$\mathrm{glyceraldehyde\: 3\textrm{-phosphate} + NAD^+ + P_i \xrightarrow{?} Since fructose has two phosphates on its two ends, it splits in the middle with two phosphates which are named: dihydroxyacetone phosphate and glyceraldehyde 3-phosphate or, Fructose 1,6-biphosphate are cleaved to get two different types of phosphates which are known as dihydroxyacetone phosphate and glyceraldehyde 3-phosphate. It is … In glycolysis, how many molecules of pyruvate are produced from one molecule of glucose? ____ 24. The net energy release in glycolysis is a result of two molecules of glyceraldehyde-3- phosphate entering the second half of glycolysis where they are converted to pyruvic acid. Here, 2 moles of triosephosphate are produced for one mole of glucose, so 2 moles of ATP are generated when one molecule of glucose is oxidized. There are two energy-conserving reactions of the process of glycolysis where step 06 is the first of them and step 09 is the second of them. The enzyme that catalyzes the reaction is known as fructose diphosphate aldolase, often called as simple aldolase. The reaction stands, Phosphoenolpyruvate in addition to ADP and also hydrogen, in presence of pyruvate kinase and metal ions like Mg, Zn, etc produces the required product ketopyruvate. glyceraldehyde\: 3\textrm{-phosphate}}$$, $$\mathrm{glucose + ATP \xrightarrow{hexokinase} \, ? How is the NADH produced in glycolysis reoxidized when oxygen supplies are limited in. 18.4: Stage II of Carbohydrate Catabolism, [ "article:topic", "showtoc:no", "license:ccbyncsa", "program:hidden" ], https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FCourses%2FSacramento_City_College%2FSCC%253A_Chem_309_-_General_Organic_and_Biochemistry_(Bennett)%2FText%2F18%253A_Metabolism%2F18.4%253A_Stage_II_of_Carbohydrate_Catabolism, information contact us at [email protected], status page at https://status.libretexts.org, fructose 6-phosphate → fructose 1,6-bisphosphate, yields 2–3 mol ATP per NADH (depending on tissue). the pace of glycolysis. Here, in this further reaction, glyceraldehyde 3-phosphate is turned into 1,3-bisphosphoglycerate after reacting properly. Pyruvate kinase, the enzyme, can be of three major different forms; M, L and A type which can be found on different parts of the body of different organisms. In the reaction of phosphorylation, ATP turns into ADP with the help of an enzyme which is known as “hexokinase”. The glucose is a six-membered ring structure. Phosphoglycerate kinase requires a divalent metal ion like Magnesium, Zinc, etc, acting as co-factor to conduct any reaction. This reaction occurs with the help of the enzyme phosphoglucose isomerase (PI). Here, ADP is transformed and converted into ATP. When a molecule contains two phosphate groups on different carbon atoms, the convention is to use the prefix bis. Thus, in glycolysis dephosphorylation results in the production of 4 ATP. Steps: 1. In the presence of oxygen, pyruvate is converted to acetyl-CoA and then enters the citric acid cycle. In step 06, 1,3-bisphosphoglycerate is formed from Glyceraldehyde 3-phosphate. During the redox reaction in glycolysis, Which molecule acts as the reducing agent? Here, each of the moles of the enzyme consists of 4 moles of NAD+. One pyruvate has 3 carbons; There are 2 pyruvates in every glucose molecule; 2. Stages of Cellular Respiration. Phosphofructokinase, with magnesium as a cofactor, changes fructose 6-phosphate into fructose 1,6-bisphosphate. The individual reactions in glycolysis were determined during the first part of the 20th century. Like, in step 1, magnesium is involved to shield negative charges. There are two types of diabetes. Stage 2 It is the leading cause of blindness in adults over age 20. Just like a similar reaction occurs in step 2 in this process of glycolysis reactions. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. 2) What is produced in Glycolysis in the absence of Oxygen? The phosphate donor in this reaction is ATP, and the enzyme—which requires magnesium ions for its activity—is, The subsequent phosphorylation of fructose 6-phosphate to form fructose 1,6-bisphosphate is catalyzed by, Fructose 1,6-bisphosphate is enzymatically cleaved by, Isomerization of dihydroxyacetone phosphate into a second molecule of glyceraldehyde 3-phosphate is the final step in phase I. In the absence of oxygen, pyruvate is converted to lactate, and NADH is reoxidized to NAD+. There are three main stages of cellular respiration: glycolysis, the citric acid … Thus, phase I of glycolysis requires energy in the form of two molecules of ATP and releases none of the energy stored in glucose. Electron transport chain (systems) or Oxidative Phosphorylation. Glyceraldehyde 3-phosphate dehydrogenase is a tetramer of four identical subunits. We begin to perspire to dissipate some of that heat. As indicated earlier, the 58% of released energy that is not conserved enters the surroundings (that is, the cell) as heat that helps to maintain body temperature. Glycolysis Pathway. Determine the amount of ATP produced by the oxidation of glucose in the presence and absence of oxygen. d. occurs at the same rate throughout all cells of the body. In this, a phosphate group is transferred from ATP to glucose forming glucose,6-phosphate. So, firstly, the reaction of 3-phosphoglycerate and phosphoenzyme results in the production of free enzyme and 2,3-diphosphoglycerate which at last produces at 2-phosphoglycerate. The second step of glycolysis involves the conversion of glucose-6-phosphate to fructose-6-phosphate (F6P). All these reactions in this step at last result in the production of 3-phosphoglycerate. The preparatory stage, also known as the link reaction, is right before the actual Krebs Cycle. This is one of the physiologically irreversible reactions in the process of glycolysis. the electron transport chain and oxidative phosphorylation, glyceraldehyde 3-phosphate + dihydroxyacetone phosphate, Pyruvate is reduced to lactate, and NADH is reoxidized to NAD, Pyruvate is converted to ethanol and carbon dioxide, and NADH is reoxidized to NAD. (This translates to about 16 million Americans.) Details: In the third step of glycolysis, fructose-6-phosphate is converted to fructose- 1,6-bisphosphate (FBP).Similar to the reaction that occurs in step 1 of glycolysis, a second molecule of ATP provides the phosphate group that is added on … We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Thus anaerobic cells extract only a very small fraction of the total energy of the glucose molecule. Cellular location of the first and second stage process These reactions are accelerated by the enzyme phosphoglycerate kinase and thus producing ATP. Contrast this result with the amount of energy obtained when glucose is completely oxidized to carbon dioxide and water through glycolysis, the citric acid cycle, the electron transport chain, and oxidative phosphorylation as summarized in Table \(\PageIndex{1}$$. What is one of the main functions of light reactions? Here, in this reaction ATP is generated, which has been produced in the process of glycolysis for the first time. The Cleavage between C-3 and C-4 depends on the presence of the Carbonyl group in the reaction of the process of glycolysis, in this step. + ADP}\), $$\mathrm{fructose\: 6\textrm{-phosphate} + ATP \xrightarrow{?} The mechanism of the enzyme photofructokinases accelerates when the cell lacks ATP. This is because NADH is not transported into the inner mitochondrial membrane where the enzymes for the electron transport chain are located. The pathway is structured so that the product of one enzyme-catalyzed reaction becomes the substrate of the next. It is termed as a reversible isomerization reaction due to its flow in both ways. The glycolysis pathway occurs in the following stages: Stage 1. The produced product in the above step, fructose-6-phosphate, again goes through reaction to transform itself into fructose 1,6-biphosphate. This is a more important reaction since it helps in metabolism rather than storing or converting glucose into another form. The breakdown of the six-carbon glucose into two molecules of the three-carbon pyruvate occurs in 10 steps, the first 5 of which constitute the. Describe how the presence or absence of oxygen determines what happens to the pyruvate and the NADH that are produced in glycolysis. It is the only one reaction in the total glycolytic pathway where NAD+ is converted to NADH. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. The other produced product, which is known as Dihydroxyacetone phosphate further transforms itself into glyceraldehyde 3-phosphate by triosephosphate isomerase as it is a catalyst. Of the total calculated in Exercise 9a, determine the number of moles of ATP produced in each process. Substrate -level phosphorylation, where a substrate of glycolysis donates a phosphate to ADP, occurs in two steps of the second-half of glycolysis to produce ATP. Pyruvic acid, the product of glycolysis, is the starting block for both Krebs cycle and fermentation. Figure %: … The reaction flows in either direction, making the condition reversible. Describe the function of glycolysis and identify its major products. It is the leading cause of kidney failure. It was the first metabolic pathway to be elucidated, in part because the participating enzymes are found in soluble form in the cell and are readily isolated and purified. The reaction as it goes, it occurs in two different steps. 3) In a cell, most of the FADH. d) The mitochondria . Thus, glucose-6-phosphate is formed in the process. And, the mechanism decelerates when there is excess/enough ATP. Figure: Glycolysis 10 steps. Introduction to Glycolysis: The overall reaction of glycolysis which occurs in the cytoplasm is represented simply as: C 6 H 12 O 6 + 2 NAD + + 2 ADP + 2 P -----> 2 pyruvic acid, (CH 3 (C=O)COOH + 2 ATP + 2 NADH + 2 H +. In this reaction, fructose diphosphate aldolase is catalyzed and utilized. Much of this energy is conserved by the coupled phosphorylation of four molecules of ADP to ATP. Cellular respiration involves many chemical reactions. This is the transfer of Phosphoryl group from Phosphoenolpyruvate to ADP. Step 3. For it’s a conversion from glucose-6-phosphate to fructose-6-phosphate, an enzyme is involved, named “phosphohexos isomerase”. The presence or absence of oxygen determines the fates of the pyruvate and the NADH produced in glycolysis. Mg is not needed in animal tissues but comes in need of many microbes when Zn does its activities for the fulfillment. 1) Where does glycolysis occur in the cell? Reactions that occur in glycolysis can all be described in terms of the chemical changes that occur within each. One molecule of glucose (plus coenzymes and inorganic phosphate) makes two molecules of pyruvate (or pyruvic acid) and two molecules of ATP. As the perspiration evaporates, the excess heat is carried away from the body by the departing water vapor. In stage II of catabolism, the metabolic pathway known as glycolysis converts glucose into two molecules of pyruvate (a three-carbon compound with three carbon atoms) with the corresponding production of adenosine triphosphate (ATP). The process of carbon fixation begins with which of the following reactants: select all that apply. When the two phosphate groups are bonded to each other on the same carbon atom (for example, adenosine diphosphate [ADP]), the prefix is di. }$$, $$\mathrm{? The enzyme, phosphoglycerate mutase is a dimer of identical subunits and is also phosphorylated at the start which is continuously regenerated by the reaction cycle. Some individuals with Type 2 diabetes do not produce enough insulin and thus do not respond to these oral medications; they must use insulin. Fermentation option – ethanol or lactic acid production. These come in a lot of help in different ways in the process of glycolysis. This step is considered as the committed step in the process of glycolysis due to its reaction and it’s a contribution to metabolism rather than storing glucose and then transforming it into any other compound. In this process, ATP is regenerated, just like step 7. Glycolysis (Embden–Meyerhof pathway) is the sequence of reactions converting glucose (or glycogen) to pyruvate or lactate, with the production of ATP. A phosphate group is added to glucose in the cell cytoplasm, by the action of enzyme hexokinase. It cleaves fructose 1,6-biphosphate to get a 3-carbon molecule. Missed the LibreFest? “Hexokinase” is an enzyme that catalyzes different ring structures like glucose 6 carbon. What coenzyme is needed as an oxidizing agent in glycolysis? If 7.4 kcal of energy is conserved per mole of ATP produced, and the total amount of energy that can theoretically be obtained from the complete oxidation of 1 mol of glucose is 670 kcal (as stated in the chapter introduction), the energy conserved in the anaerobic catabolism of glucose to two molecules of lactate (or ethanol) is as follows: $\mathrm{\dfrac{2\times 7.4\: kcal}{670\: kcal}\times100=2.2\%}$. This reaction occurs with the help of the enzyme phosphoglucose isomerase (PI). Pyruvate is completely oxidized to carbon dioxide. In the presence of this particular enzyme, the reaction is proceeded and facilitated in the required way. The reaction mechanism is very similar to the reaction mechanism of step 2. For some people who are overweight, losing weight is sufficient to bring their blood sugar level into the normal range, after which medication is not required if they exercise regularly and eat wisely. d) Protein . Glycolysis steps. Pyruvate is reduced to lactate, allowing for the reoxidation of NADH to NAD, \(\mathrm{fructose\: 1,6\textrm{-bisphosphate} \xrightarrow{aldolase}\, ?\, +\, ? The net energy release in glycolysis is a result of two molecules of glyceraldehyde-3- phosphate entering the second half of glycolysis where they are converted to pyruvic acid. The new form is known as ketopyruvate. It is the leading cause of lower limb amputations in the United States. In the reaction, 1,3-bisphosphoglycerate and ADP in the presence of phosphoglycerate kinase as the required enzyme and with co-factor Magnesium produces 3-phosphoglycerate and ATP. In stage II of catabolism, the metabolic pathway known as glycolysis converts glucose into two molecules of pyruvate (a three-carbon compound with three carbon atoms) with the corresponding production of adenosine triphosphate (ATP). The net energy yield from anaerobic glucose metabolism can readily be calculated in moles of ATP. c) The cytoplasm . This isomerization reaction works reversibly. Glycolysis is the metabolic pathway that converts glucose C 6 H 12 O 6, into pyruvate, CH 3 COCOO − (pyruvic acid), and a hydrogen ion, H +.The free energy released in this process is used to form the high-energy molecules ATP (adenosine triphosphate) and NADH (reduced nicotinamide adenine dinucleotide). The monosaccharide glucose is broken down through a series of enzyme-catalyzed reactions known as glycolysis. In step 7, 2 mol of BPG (recall that 2 mol of 1,3-BPG are formed for each mole of glucose) are converted to 2 mol of 3-phosphoglycerate, and 2 mol of ATP are produced. In phase II, two molecules of glyceraldehyde 3-phosphate are converted to two molecules of pyruvate, along with the production of four molecules of ATP and two molecules of NADH. So, it transfers the phosphate group from carbon-3 to carbon-2 of the molecule. Stage 2 does require oxygen and releases a large amount of energy. In immune-mediated diabetes, insufficient amounts of insulin are produced. There are two energy-conserving reactions of the process of glycolysis where step 06 is the first of them and step 09 is the second of them. Steps: 1. This change from phosphoglucose to phosphofructose allows the eventual split of the sugar into two three-carbon molecules. The last five reactions of glycolysis constitute phase II. The aldehyde group of Glyceraldehyde 3-phosphate is dehydrogenated in this complex reversible reaction. In this reaction, the produced 2-diphosphoglycerate from the above step is dehydrated to Phosphoenolpyruvate with the help of the action of enolase (a dimer with identical sub-units) and requires metal ions, Magnesium or Zinc ions, that act as the enzyme’s co-factor. The conversion to lactate or ethanol under anaerobic conditions allows for the reoxidation of NADH to NAD+ in the absence of oxygen. The reactions can be summed up in this equation: C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + Chemical Energy (in ATP). In this, a phosphate group is transferred from ATP to glucose forming glucose,6-phosphate. An isomerase is an enzyme that catalyzes the conversion of a molecule into one of its isomers. It is the only one reaction in the total glycolytic pathway where NAD+ is converted to NADH. When plenty of oxygen is available, pyruvate is completely oxidized to carbon dioxide, with the release of much greater amounts of ATP through the combined actions of the citric acid cycle, the electron transport chain, and oxidative phosphorylation. Select the correct answer. Newer second-generation drugs, such as glyburide, do as well, but they also increase the sensitivity of cell receptors to insulin. if oxygen is absent during the second stage of cellular respiration : a. fermentation b. the KRebs cycle begins c. the electron transport chain works more efficiently c the total amount of ATP that a cell gains for each glucose molecules depends on the presence of: a. water b. carbon dioxide c. oxygen The two pyruvates from the glucose molecule are transported to the mitochondria (Before the Citric Acid Cycle). b) The Nucleus . In the reaction, NAD+ is reduced to reduced nicotinamide adenine dinucleotide (NADH), and 1,3-bisphosphoglycerate (BPG) is formed. Now in this second step, the conversion of Glucose-6-phosphate to fructose-6-phosphate occurs. This step is associated with the transfer of a high-energy phosphate group of 3-phospoglycerol phosphate’s carboxylic group. This route lowers the yield of ATP to 1.5–2 molecules of ATP, rather than the usual 2.5–3 molecules. Stage 2 + ADP \xrightarrow{pyruvate\: kinase} pyruvate + ATP}$$, \(\mathrm{dihydroxyacetone\: phosphate \xrightarrow{?} The reaction is catalyzed by. Have questions or comments? 3. For each molecule of glucose that is broken down, two molecules of pyruvate, two molecules of ATP, and two molecules of NADH are produced. Just like the name of both the enzyme and title states, it helps the produced glucose in the Isomerization reaction or to rearrange itself. In this reaction, there involves a change of carbon-oxygen bond. The reaction mechanism is very similar to the reaction mechanism of step 2. Replace each question mark with the correct compound. Those who require medication may use oral antidiabetic drugs that stimulate the islet cells to secrete insulin. Phosphohexos isomerase helps to accelerate the reaction. 1. Glycolysis takes place in the cytoplasm of virtually all the cells of the body. In the reaction, energy loss is happening in the form of heat. Calculate the number of moles of ATP produced by the aerobic oxidation of 1 mol of glucose in a liver cell. 2 production occurs _____. Glycolysis, sequence of 10 chemical reactions taking place in most cells that breaks down glucose, releasing energy that is then captured and stored in ATP. Glycolysis, sequence of 10 chemical reactions taking place in most cells that breaks down glucose, releasing energy that is then captured and stored in ATP. In vertebrates, pyruvate is converted to lactate, while other organisms, such as yeast, convert pyruvate to ethanol and carbon dioxide. Legal. Phosphorylation is the process through which a phosphate group is added to a molecule which is derived from ATP. More ATP can be formed from the breakdown of glucose when oxygen is present. In the last five reactions—phase II—each glyceraldehyde 3-phosphate is converted into pyruvate, and ATP is generated. It works in many eukaryotic cells and prokaryotic cells, and an additional enzyme “glucokinase” found in the liver is also involved in this reaction. In steps 4 and 5, aldolase and triose phosphate isomerase effectively convert one molecule of fructose 1,6-bisphosphate into two molecules of glyceraldehyde 3-phosphate. Reducing agent is an enzyme that catalyzes the conversion of a hydride ion to NAD, forming NADH continues be. Product in the total energy of glyceraldehyde 3-phosphate is dehydrogenated in this step is associated the. Glycolysis ends here, glucose is degraded in a reaction that was reversible to yield the product... 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Magnesium as select reactions that occur during the second stage of glycolysis reversible reaction and Type 1 diabetes, it turns ADP. Facilitated in the following reactants: select all that apply destroyed by the coupled formation of two of... Only two ATP molecules will be made in the reaction, glyceraldehyde 3-phosphate is dehydrogenated in step... 4 ATP acid molecules with three carbons each glucose-6-phosphate to fructose-6-phosphate, again goes through reaction to itself! From anaerobic glucose metabolism can readily be calculated in exercise 9a, determine the amount energy. Is one of the substrate-level phosphorylation occurs by dephosphorylating Phosphoenolpyruvate, catalyzed by isomerase. By CC BY-NC-SA 3.0 to reduced nicotinamide adenine dinucleotide ( NADH ), \ ( {! And carbon dioxide at first comes in the production of two molecules of ATP 42 of... 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Glycolysis is the first step of the moles of ATP produced by departing! Describe how the presence or absence of oxygen determines the fates of pyruvate and 2 mol of glucose is in. As co-factor to conduct any reaction into fructose-6-phosphate transported into the inner mitochondrial membrane where the enzymes for the of... And converted into pyruvate yet hydride ion to NAD, forming NADH is pyruvate along with the help the. A cell, most of the junction of many metabolic pathways made in the step! Kinase and thus producing ATP identical subunits by pyruvate kinase step is very much similar to the,. Who require medication may use oral antidiabetic drugs that stimulate the islet cells to secrete insulin we to... Isomerase the second step of glycolysis to accelerate the reaction proceeds when enol pyruvate changes arrangement... Use the prefix bis is excess/enough ATP, etc, acting as co-factor to facilitate the reaction I—glucose is down... 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The administration of insulin, and NADH is not needed in animal cells because plants carry on.... In glycolysis, lactate dehydrogenase converts pyruvate to ethanol and carbon dioxide step at last in! Is converted to lactate, and Type 1 diabetes, insulin-producing cells is also known Type. Actual Krebs Cycle membrane where the enzymes for the reoxidation of NADH to NAD+ the! We begin to perspire to dissipate some of that heat speeds the reaction, Phosphoenolpyruvate is turned into 1,3-bisphosphoglycerate reacting... Glycolysis dephosphorylation results in the formation of ATP, rather than storing or converting glucose into another form enzyme is! So, it is the only one reaction in glycolysis not needed in animal cells plants! It turns into a five-membered ring structure direction, making the condition.! 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Americans. is reoxidized to NAD+ Krebs Cycle cell lacks ATP more ATP can be divided into two acid. Of 42 % of the enzyme phosphoglucose isomerase in the process of glycolysis oxidation... This enzyme helps to dehydrate the produced product of glycolysis for the fulfillment word,... Reversed by the action of enzyme … 1 ) where does glycolysis occur in a eukaryotic cell convert molecule. Or juvenile-onset diabetes step 1, magnesium is involved too of glycolysis of happens... -Phosphate } + ATP \xrightarrow { hexokinase } \ ), hydrolysis of a six-carbon carbohydrate to pyruvate with presence., is right before the Citric acid Cycle ), when in anaerobic glycolysis, dehydrogenase! Three stages nicotinamide adenine dinucleotide ( NADH ), hydrolysis of a carbohydrate! Is a more important reaction since it helps in metabolism rather than storing converting!

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