diabetestalk.net

Catabolism Of Glucose

Glycolysis - Glucose Catabolic Pathway

Glycolysis - Glucose Catabolic Pathway

The major function of carbohydrates in metabolism is as a fuel to be oxidized and provide energy for other metabolic processes. The carbohydrate is utilized by cells mainly as glucose. The three principal monosaccharide resulting from digestive processes are glucose, fructose and galactose. Much of the glucose is derived from starch which accounts for ever half of the fuel in the diets of most humans. Determination of Carbohydrate by Anthrone Method Glucose is also produced from other dietary components by the liver and, to a lesser extent, by the kidneys. Fructose results on large intake of sucrose while Galactose is produced when lactose is the principal carbohydrate of the diet. Both fructose and Galactose are easily converted to glucose by the liver. It is thus apparent that glucose is the major fuel of most organisms and that it can be quickly metabolized from glycogen stores when there arises a sudden need for energy. Glucose transporters are Glucose transporting proteins. Usually glucose is transported into the cells by sodium-glucose pump. In addition to symport pump, most of the cells have another type of transport proteins called Glucose Transporters (GLUT). So far, six types of GLUT are identified (GLUT 1-5 and 7). Among these, GLUT-4 is insulin sensitive and it is located in cytoplasmic vesicles. It is present in large numbers in muscle fibers and adipose cells. When insulin-receptor complex is formed in the membrane of such cells, the vesicles containing GLUT-4 are attracted towards the membrane and GLUT-4 is released into the membrane. Now, GLUT-4 starts transporting the glucose molecules from ECF into the cell. The advantage of GLUT-4 is that it transports glucose at a faster rate. This is the first phase of Glycolysis. In this Glucose is converted into Continue reading >>

26.7: The Catabolism Of Carbohydrates

26.7: The Catabolism Of Carbohydrates

Describe the function of glycolysis and identify its major products. Describe how the presence or absence of oxygen determines what happens to the pyruvate and the NADH that are produced in glycolysis. Determine the amount of ATP produced by the oxidation of glucose in the presence and absence of oxygen. 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 individual reactions in glycolysis were determined during the first part of the 20th century. 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 pathway is structured so that the product of one enzyme-catalyzed reaction becomes the substrate of the next. The transfer of intermediates from one enzyme to the next occurs by diffusion. The 10 reactions of glycolysis, summarized in Figures \(\PageIndex{1}\) and \(\PageIndex{2}\), can be divided into two phases. In the first 5 reactionsphase Iglucose is broken down into two molecules of glyceraldehyde 3-phosphate. In the last five reactionsphase IIeach glyceraldehyde 3-phosphate is converted into pyruvate, and ATP is generated. Notice that all the intermediates in glycolysis are phosphorylated and contain either six or three carbon atoms. Figure \(\PageIndex{1}\):Phase 1 of Glycolysis When glucose enters a cell, it is immediately phosphorylated to form glucose 6-phosphate, in the first reaction of phase I. The phosphate donor in this reaction is ATP, and the enzymewhich requires magnesium ions for its activityis hexokinase. In this reaction, ATP is being used rather th Continue reading >>

5 The Complete Catabolism Of Glucose Can Yield 686 Kcalmol Energy Transfer For

5 The Complete Catabolism Of Glucose Can Yield 686 Kcalmol Energy Transfer For

5. The complete catabolism of glucose can yield 686 kcal/mol energy transfer. For each of the following statements, indicate whether the statement is true or false and then explain your answer. A. All 686 kcal/mol is directly transferred to ATP synthesis. TRUE FALSE [choose one, then explain] Slightly less than half (234 kcal/mol) is transferred to ATP synthesis; albeit imperfect, the efficiency of this transfer is highly efficient compared to the best motors devised by humans. B. Less than half of the 686 kcal/mol is directly transferred to ATP synthesis. TRUE FALSE [choose one, then explain] 234 kcal/mol, or slightly less than half, is transferred to ATP synthesis. C. Only 10% of the 686 kcal/mol is directly transferred to ATP synthesis, in accordance with the principles of thermodynamics. TRUE FALSE [choose one, then explain] The first law of thermodynamics states that energy cannot be created nor destroyed, and therefore the total amount of energy in a closed system remains constant. Even though less than half of the energy produced during cellular respiration is transferred to ATP synthesis, the remainder is not destroyed but is given off as heat. Therefore, energy changes form but is not lost by this metabolic process. The second law states that the amount of available energy in a closed system is continually decreasing, or that entropy is increasing. While the efficiency of ATP synthesis is greater than 10%, it is not 100% efficient, nor is any other physical process or chemical reaction. Biological processes all tend to increase entropy, and the tendency gives direction to these processes. Changes in entropy are mathematically related to changes in free energy, which explains why some reactions proceed in one direction rather than another. Continue reading >>

Glucose Catabolism In Cancer Cells.

Glucose Catabolism In Cancer Cells.

ISOLATION, SEQUENCE, AND ACTIVITY OF THE PROMOTER FOR TYPE II HEXOKINASE (*) From the (1)Laboratory for Molecular and Cellular Bioenergetics, Department of Biological Chemistry, The Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205 To whom correspondence should be addressed. Tel.: 410-955-3827; Fax: 410-955-5759. One of the most characteristic phenotypes of rapidly growing cancer cells is their propensity to catabolize glucose at high rates. Type II hexokinase, which is expressed at high levels in such cells and bound to the outer mitochondrial membrane, has been implicated as a major player in this aberrant metabolism. Here we report the isolation and sequence of a 4.3-kilobase pair proximal promoter region of the Type II hexokinase gene from a rapidly growing, highly glycolytic hepatoma cell line (AS-30D). Analysis of the sequence enabled the identification of putative promoter elements, including a TATA box, a CAAT element, several Sp-1 sites, and response elements for glucose, insulin, cAMP, Ap-1, and a number of other factors. Transfection experiments with AS-30D cells showed that promoter activity was enhanced 3.4-, 3.3-, 2.4-, 2.1-, and 1.3-fold, respectively, by glucose, phorbol 12-myristate 13-acetate (a phorbol ester), insulin, cAMP, and glucagon. In transfected hepatocytes, these same agents produced little or no effect. The results emphasize normal versus tumor cell differences in the regulation of Type II hexokinase and indicate that transcription of the Type II tumor gene may occur independent of metabolic state, thus, providing the cancer cell with a selective advantage over its cell of origin. The ability to maintain an increased rate of glucose utilization and the capacity to sustain high rates of glycolysis under aerobic conditio Continue reading >>

Catabolism Of Carbohydrates

Catabolism Of Carbohydrates

Describe why glycolysis is not oxygen dependent Define and describe the net yield of three-carbon molecules, ATP, and NADH from glycolysis Explain how three-carbon pyruvate molecules are converted into two-carbon acetyl groups that can be funneled into the Krebs cycle. Define and describe the net yield of CO2, GTP/ATP, FADH2, and NADH from the Krebs cycle Explain how intermediate carbon molecules of the Krebs cycle can be used in a cell Extensive enzyme pathways exist for breaking down carbohydrates to capture energy in ATP bonds. In addition, many catabolic pathways produce intermediate molecules that are also used as building blocks for anabolism. Understanding these processes is important for several reasons. First, because the main metabolic processes involved are common to a wide range of chemoheterotrophic organisms, we can learn a great deal about human metabolism by studying metabolism in more easily manipulated bacteria like E. coli. Second, because animal and human pathogens are also chemoheterotrophs, learning about the details of metabolism in these bacteria, including possible differences between bacterial and human pathways, is useful for the diagnosis of pathogens as well as for the discovery of antimicrobial therapies targeting specific pathogens. Last, learning specifically about the pathways involved in chemoheterotrophic metabolism also serves as a basis for comparing other more unusual metabolic strategies used by microbes. Although the chemical source of electrons initiating electron transfer is different between chemoheterorophs and chemoautotrophs, many similar processes are used in both types of organisms. The typical example used to introduce concepts of metabolism to students is carbohydrate catabolism. For chemoheterotrophs, our examples of m Continue reading >>

Glucose Catabolism Flashcards | Quizlet

Glucose Catabolism Flashcards | Quizlet

What is the process that converts glucose to 2 pyruvic acid molecules? How many ATP molecules are produced during glycolysis (net production)? What are the two steps of aerobic respiration? Krebs cycle and oxidative phosphorylation (ETC) How many ATP molecules are generated during the Krebs cycle? Before entering the Krebs cycle, pyruvic acid is converted to... In the first step of the Krebs cycle, acetyl CoA joins with a molecule containing how many carbon atoms? 4-carbon molecule (which results in a 6-carbon molecule) As carbon atoms are removed from carbon compounds during the Krebs cycle, they join with.... What is the main point of the Krebs cycle? to transfer the energy in pyruvic acid into the high energy molecules NADH and FADH2 What is the role of NADH and FADH2 in the electron transport chain? What is another name for the electron transport chain and chemiosmosis working together to produce ATP molecules from ADP? At the end of the electron transport chain, the electrons join with which atom? oxygen to form water (one of the products of cellular respiration) Approximately how many ATP molecules are produced by oxidative phosphorylation? Which is more efficient - aerobic respiration or anaerobic respiration? Continue reading >>

Equation For Glucose Metabolism

Equation For Glucose Metabolism

The cells in your body can break down or metabolize glucose to make the energy they need. Rather than merely releasing this energy as heat, however, cells store this energy in the form of adenosine triphosphate or ATP; ATP acts as a kind of energy currency that's available in a convenient form to meet the cell's needs. Overall Chemical Equation Since the breakdown of glucose is a chemical reaction, it can be described using the following chemical equation: C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O, where 2870 kilojoules of energy are released for each mole of glucose that's metabolized. Although this equation does describe the overall process, its simplicity is deceptive, because it conceals all the details of what's really taking place. Glucose isn't metabolized in a single step. Instead, the cell breaks glucose down in a series of small steps, each of which releases energy. The chemical equations for these appear below. Glycolysis The first step in glucose metabolism is glycolysis, a ten-step process where a molecule of glucose is lysed or split into two three-carbon sugars which are then chemically altered to form two molecules of pyruvate. The net equation for glycolysis is as follows: C6H12O6 + 2 ADP + 2 [P]i + 2 NAD+ --> 2 pyruvate + 2 ATP + 2 NADH, where C6H12O6 is glucose, [P]i is a phosphate group, NAD+ and NADH are electron acceptors/carriers and ADP is adenosine diphosphate. Again, while this equation gives the overall picture, it also conceals a lot of the dirty details; since glycolysis is a ten-step process each step could be described using a separate chemical equation. Citric Acid Cycle The next step in glucose metabolism is the citric acid cycle (also called the Krebs cycle or the tricarboxylic acid cycle). Each of the the two molecules of pyruvate formed by gly Continue reading >>

Catabolism Of Sugars Other Than Glucose

Catabolism Of Sugars Other Than Glucose

Catabolism of sugars other than glucose Starch is the most abundant carbohydrate in our diet, which makes glucose the most important dietary monosaccharide. However, our diet contains several other sugars in significant amounts. The guiding motif in the metabolism of these sugars is economy: instead of completely separate degradative pathways, there are short adapter pathways which merge into the main pathway of carbohydrate degradation, that is, glycolysis. Lactose and sucrose are disaccharides. Degradation of both sugars begins with hydrolytic cleavage, which releases glucose and galactose or glucose and fructose, respectively. Fructose is also found in the diet as a monosaccharide. We already know how glucose is degraded, so we here only need to concern ourselves with the remaining monosaccharides. The degradation of sorbitol will be discussed as well, whereas ribose and deoxyribose will be covered in later chapters. Sucrose is produced from sugar cane and sugar beet, which contain it in high concentrations (1520%). In a typical Western diet, it may amount to as much as 20% of the total carbohydrate intake. Sucrose consists of glucose and fructose joined by a -glycosidic bond between the carbon 1 of glucose and carbon 2 of fructose. The hydrolytic cleavage of sucrose, like that of of maltose, occurs at the surface of the intestinal epithelial cells. The enzyme responsible is -fructosidase, also named sucrase. Both sugars are then taken up by specific transport: Glucose by the SGLT1 transporter, and fructose by the GLUT5 transporter, which is named after glucose but actually transports fructose more effectively than glucose. Fructose degradation, also called fructolysis, runs mostly in the liver. In the first step, fructose is phosphorylated by fructokinase (1), whic Continue reading >>

Metabolism Of Molecules Other Than Glucose

Metabolism Of Molecules Other Than Glucose

You have learned about the catabolism of glucose, which provides energy to living cells. But living things consume more than just glucose for food. How does a turkey sandwich, which contains various carbohydrates, lipids, and protein, provide energy to your cells? Basically, all of these molecules from food are converted into molecules that can enter the cellular respiration pathway somewhere. Some molecules enter at glycolysis, while others enter at the citric acid cycle. This means that all of the catabolic pathways for carbohydrates, proteins, and lipids eventually connect into glycolysis and the citric acid cycle pathways. Metabolic pathways should be thought of as porous—that is, substances enter from other pathways, and other substances leave for other pathways. These pathways are not closed systems. Many of the products in a particular pathway are reactants in other pathways. Carbohydrates So far, we have discussed the carbohydrate from which organisms derive the majority of their energy: glucose. Many carbohydrate molecules can be broken down into glucose or otherwise processed into glucose by the body. Glycogen, a polymer of glucose, is a short-term energy storage molecule in animals (Figure 1). When there is plenty of ATP present, the extra glucose is converted into glycogen for storage. Glycogen is made and stored in the liver and muscle. Glycogen will be taken out of storage if blood sugar levels drop. The presence of glycogen in muscle cells as a source of glucose allows ATP to be produced for a longer time during exercise. Figure 1 Glycogen is made of many molecules of glucose attached together into branching chains. Each of the balls in the bottom diagram represents one molecule of glucose. (Credit: Glycogen by BorisTM. This work has been released into Continue reading >>

Initial Step In Catabolism Of Glucose By The Meningopneumonitis Agent

Initial Step In Catabolism Of Glucose By The Meningopneumonitis Agent

Initial Step in Catabolism of Glucose by the Meningopneumonitis Agent This article has been cited by other articles in PMC. The relative rates of catabolism of glucose and glucose-6-phosphate by intact-cell suspensions of the meningopneumonitis agent, a member of the psittacosis group (Chlamydia), and the properties of the hexokinase and glucose-6-phosphate dehydrogenase of these suspensions were investigated. It is proposed that the hexokinase is a host enzyme bound to the surface of the meningopneumonitis cell and that glucose-6-phosphate is the first substrate in the conversion of hexose to pentose to be attacked by enzymes synthesized by the meningopneumonitis agent. Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (505K), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References . These references are in PubMed. This may not be the complete list of references from this article. FRAENKEL DG, FALCOZ-KELLY F, HORECKER BL. THE UTILIZATION OF GLUCOSE 6-PHOSPHATE BY GLUCOKINASELESS AND WILD-TYPE STRAINS OF ESCHERICHIA COLI. Proc Natl Acad Sci U S A. 1964 Nov;52:12071213. [ PMC free article ] [ PubMed ] LOWRY OH, ROSEBROUGH NJ, FARR AL, RANDALL RJ. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265275. [ PubMed ] MOULDER JW, GRISSO DL, BRUBAKER RR. ENZYMES OF GLUCOSE CATABOLISM IN A MEMBER OF THE PSITTACOSIS GROUP. J Bacteriol. 1965 Mar;89:810812. [ PMC free article ] [ PubMed ] Rose IA, Warms JV. Mitochondrial hexokinase. Release, rebinding, and location. J Biol Chem. 1967 Apr 10;242(7):16351645. [ PubMed ] Weiss E. Adenosine Triphosphate and Other Requirements for the Utilization of Glucose by Agents of Continue reading >>

Structural Biochemistry/catabolism

Structural Biochemistry/catabolism

Catabolism is the release of energy from a set of metabolic pathways which break down molecules into smaller units, including the breaking down and oxidizing of food molecules. An example would be proteins , nucleic acids , lipids and polysaccharides being broken down into smaller molecules like amino acids , nucleotides, fatty acids , and mono saccharides . By glycolysis, the glucose is broken down into two pyruvates which can be used for later mechanism (Krebs cycle) to produce energy. The oxidation of long-chain fatty acid to acetyl-CoA is a central energy-yielding pathway in many organisms. Its opposite process is anabolism , which combines small molecules into larger molecules. Energy that is released from catabolism will store as ATP within the cell. The cell will then use this source of energy for synthesizing cell components from simple precursors, for the mechanical work of contraction and motion, and for transport of substances across its membrane. Catabolism maintains the chemical energy needed in order to help the cell grow and develop. Some waste products caused by catabolism are carbon dioxide, urea, and lactic acid. Heat is also sometimes released as a by product because these are oxidation processes. Examples of catabolism are the citric acid cycle. The energy cells contain is liberated through two distinct processes: glycolysis and cellular respiration GLYCOLYSIS Glycolysis is a series of reactions that break down glucose into two smaller organic molecules. Glycolytic pathway Glycolysis occurs in the cytoplasm, in the presence or absence of oxygen. The pathway has several steps to convert six-carbon glucose into two molecules of three-carbon pyruvates. The direct generation of ATP from ADP and Pi is known as substrate-level phosphorylation. NAD+ is red Continue reading >>

Chapter 14 : Glycolysis And The Catabolism Of Hexoses

Chapter 14 : Glycolysis And The Catabolism Of Hexoses

Having examined the organizing principles of cell metabolism and bioenergetics, we are ready to see how the chemical energy stored in glucose and other fuel molecules is released to perform biological work. -Glucose is the major fuel of most organisms and occupies a central position in metabolism. It is relatively rich in potential energy; its complete oxidation to carbon dioxide and water proceeds with a standard free-energy change of -2,840 kJ/mol. By storing glucose as a high molecular weight polymer, a cell can stockpile large quantities of hexose units while maintaining a relatively low cytosolic osmolarity. When the cell's energy demands suddenly increase, glucose can be released quickly from these intracellular storage polymers. Glucose is not only an excellent fuel, it is also a remarkably versatile precursor, capable of supplying a huge array of metabolic intermediates, the necessary starting materials for biosynthetic reactions. E. coli can obtain from glucose the carbon skeletons for every one of the amino acids, nucleotides, coenzymes, fatty acids, and other metabolic intermediates needed for growth. A study of the numerous metabolic fates of glucose would encompass hundreds or thousands of transformations. In the higher plants and animals glucose has three major fates: it may be stored (as a polysaccharide or as sucrose), oxidized to a three-carbon compound (pyruvate) via glycolysis, or oxidized to pentoses via the pentose phosphate (phosphogluconate) pathway (Fig. 14-1). This chapter begins with a description of the individual reactions that constitute the glycolytic pathway and of the enzymes that catalyze them. We then consider fermentation, the operation of the glycolytic pathway under anaerobic conditions. The sources of glucose units for glycolysis a Continue reading >>

Carbohydrate Catabolism

Carbohydrate Catabolism

Digestion is the breakdown of carbohydrates to yield an energy rich compound called ATP . The production of ATP is achieved through the oxidation of glucose molecules. In oxidation, the electrons are stripped from a glucose molecule to reduce NAD+ and FAD . NAD+ and FAD possess a high energy potential to drive the production of ATP in the electron transport chain . ATP production occurs in the mitochondria of the cell. There are two methods of producing ATP: aerobic and anaerobic . In aerobic respiration, oxygen is required. Oxygen plays a key role as it increases ATP production from 4 ATP molecules to about 30 ATP molecules. In anaerobic respiration, oxygen is not required. When oxygen is absent, the generation of ATP continues through fermentation.There are two types of fermentation: alcohol fermentation and lactic acid fermentation . There are several different types of carbohydrates : polysaccharides (e.g., starch , amylopectin , glycogen , cellulose ), monosaccharides (e.g., glucose , galactose , fructose , ribose ) and the disaccharides (e.g., sucrose , maltose , lactose ). Glucose reacts with oxygen in the following redox reaction, C6H12O6 + 6O2 6CO2 + 6H2O, Carbon dioxide and water are waste products, and the overall reaction is exothermic . The breakdown of glucose into energy in the form of molecules of ATP is therefore one of the most important biochemical pathways found in living organisms. Glycolysis , which means sugar splitting, is the initial process in the cellular respiration pathway. Glycolysis can be either an aerobic or anaerobic process. When oxygen is present, glycolysis continues along the aerobic respiration pathway. If oxygen is not present, then ATP production is restricted to anaerobic respiration . The location where glycolysis, aerobic or Continue reading >>

Solved: 1.the Complete Catabolism Of Glucose Forms _____ C... | Chegg.com

Solved: 1.the Complete Catabolism Of Glucose Forms _____ C... | Chegg.com

home / study / science / biology / biology questions and answers / 1.The Complete Catabolism Of Glucose Forms _____ CO2 Molecules And _____ ATP Molecules. 2. ... Question: 1.The complete catabolism of glucose forms _____ CO2molecules and _____ ATP molecules.2. Pyruva... 1.The complete catabolism of glucose forms _____ CO2molecules and _____ ATP molecules. 2. Pyruvate is converted to _____ under anaerobicconditions. 3. _____ and glucose are obtained by the hydrolysis ofthe disaccharide sucrose, found in sugar beets andsugarcane. 4. By the end of step [4] of the citric acid cycle,_____ carbons are lost as CO2 and _____ molecules of NADH areformed. 5. At the endof the electron transport chain, the electrons and protons(obtained from the reduced coenzymes or the matrix of themitochondrion) react with inhaled oxygen to form_____. 6. The reduced coenzymes formed in the citric acid cycleenter the _____. 7. The mainfunction of the citric acid cycle is to produce reduced coenzymesthat enter the electron transport chain and ultimately produce_____. 8. _____ is acyclic metabolic pathway that begins with the addition of acetylCoA to a four-carbon substrate, and ends when the same four-carboncompound is formed as a product eight steps later. 1.The complete catabolism of glucose forms 6 CO2 molecules and 36 or 38 ATP molecules. 2. Pyruvate is converted to lactate under anaerobic conditions. 3.Fructose and glucose are obtained by the hydr... view the full answer Continue reading >>

Concepts Of Biology

Concepts Of Biology

CO2 + H2O + energy (ATP = chemical energy, heat) A. So, what can we learn/deduce from this equation: Glucose catabolism is essentially the "reverse" of photosynthesis Glucose catabolism is a redox reaction. Glucose (carbohydrate) is oxidized to carbon dioxide. The acceptor for the electrons is oxygen which is reduced to water. The chemical bond energy of glucose is released as ATP and heat This is the primary source of ATP for all aerobic organisms B. Hill Model Revisited - a diagram of the hill will be provided in class. Some take-home-lessons from the hilltop: Anabolism (synthetic reactions) is analogous to pushing the rock uphill, catabolism (degradative reactions) is analogous to the rock rolling downhill; Photosynthesis (an anabolic process) is analogous to pushing the rock uphill, respiration (a catabolic process) is analogous to the rock rolling downhill; The energy required to push the rock (glucose) uphill comes from light (radiant energy); The release of energy from glucose rolling downhill is coupled to ATP production (ca. 40% of the energy is trapped in ATP but more than half of the energy is lost as heat). II. Rolling metabolic rocks downhill - A look at Glucose Catabolism Glucose catabolism occurs in a series of small, sequential, highly controlled and regulated steps (reactions). The processes involved are glycolysis, which is the first step of glucose breakdown, and it is followed by either fermentation or cellular respiration (depending on the availability of oxygen). Why so many steps? Back to our hill model for an answer. There are two kinds of hills - those with a gradual, step-wise slope and those with a steep precipice or overhang. In each case the rock will roll down the hill and release the same total amount of energy, which is equal to the ener Continue reading >>

More in diabetes