Which Metabolic Process Refers To The Breakdown Of Glycogen To Glucose

Principles Of Biochemistry/gluconeogenesis And Glycogenesis

Gluconeogenesis (abbreviated GNG) is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids. It is one of the two main mechanisms humans and many other animals use to keep blood glucose levels from dropping too low (hypoglycemia). The other means of maintaining blood glucose levels is through the degradation of glycogen (glycogenolysis). Gluconeogenesis is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms. In animals, gluconeogenesis takes place mainly in the liver and, to a lesser extent, in the cortex of kidneys. This process occurs during periods of fasting, starvation, low-carbohydrate diets, or intense exercise and is highly endergonic. For example, the pathway leading from phosphoenolpyruvate to glucose-6-phosphate requires 6 molecules of ATP. Gluconeogenesis is often associated with ketosis. Gluconeogenesis is also a target of therapy for type II diabetes, such as metformin, which inhibits glucose formation and stimulates glucose uptake by cells. Lactate is transported back to the liver where it is converted into pyruvate by the Cori cycle using the enzyme lactate dehydrogenase. Pyruvate, the first designated substrate of the gluconeogenic pathway, can then be used to generate glucose. All citric acid cycle intermediates, through conversion to oxaloacetate, amino acids other than lysine or leucine, and glycerol can also function as substrates for gluconeogenesis.Transamination or deamination of amino acids facilitates entering of their carbon skeleton into the cycle directly (as pyruvate or oxaloacetate), or indirectly via the citric acid cycle. Whether fatty acids can be converted into glucose in animals has been a longst Continue reading >>

Glycogenolysis And Glycogenesis

Structure of glycogen Figure 1. Glycogen structure (Click for enlarged view). Panel A. Schematic two-dimensional cross-sectional view of glycogen: A core protein of glycogenin is surrounded by branches of glucose units. The entire globular granule may contain around 30,000 glucose units. [Source: Mikael Häggström[2], . Panel B. Schematic of glycogen structure showing the glucose units in each chain linked together linearly by α(1→4 glycosidic bonds. Branches are linked to the chains from which they are branching off by α(1→6) glycosidic bonds between the first glucose of the new branch and a glucose on the stem chain.Glycogen is a multi-branched polysaccharide of glucose that serves as an energy store primarily in muscle and liver. It is stored in the form of granules in the cytoplasm of the cell and is the main storage form of glucose in the body. The concentration of glycogen in muscle is low (1-2% fresh weight) compared to the levels stored in the liver (up to 8% fresh weight)[1]. Glycogen is an energy reserve that can be quickly mobilized to meet a sudden need for glucose. The significance of the multi-branched structure is that multiple glucose units, rather than a single glucose can be mobilized from any glycogen molecule when glycogenolysis is initiated. The structure of glycogen is summarized in Figure 1[2]. Enzymes involved in glycogenolysis The process of glycogenolysis involves the sequential removal of glucose monomers by phosphorolysis, a reaction catalysed by the phosphorylated (active) ‘a’ form of the enzyme glycogen phosphorylase[3]. This enzyme cleaves the glycosidic bond linking a terminal glucose to a glycogen branch by substituting a phosphoryl group for the α[1→4] linkage producing glucose-1-phosphate and glycogen that contains one le Continue reading >>

Glycogen Biosynthesis; Glycogen Breakdown

Glycogen is a polymer of glucose (up to 120,000 glucose residues) and is a primary carbohydrate storage form in animals. The polymer is composed of units of glucose linked alpha(1-4) with branches occurring alpha(1-6) approximately every 8-12 residues. The end of the molecule containing a free carbon number one on glucose is called a reducing end. The other ends are all called non-reducing ends. Related polymers in plants include starch (alpha(1-4) polymers only) and amylopectin (alpha (1-6) branches every 24-30 residues). Glycogen provides an additional source of glucose besides that produced via gluconeogenesis. Because glycogen contains so many glucoses, it acts like a battery backup for the body, providing a quick source of glucose when needed and providing a place to store excess glucose when glucose concentrations in the blood rise. The branching of glycogen is an important feature of the molecule metabolically as well. Since glycogen is broken down from the "ends" of the molecule, more branches translate to more ends, and more glucose that can be released at once. Liver and skeletal muscle are primary sites in the body where glycogen is found. The primary advantagesof storage carbohydrates in animals are that 1) energy is not released from fat (other majorenergy storage form in animals) as fast as from glycogen; 2) glycolysis provides a mechanism of anaerobic metabolism (importantin muscle cells that cannot get oxygen as fast as needed); and 3) glycogen provides a means of maintaining glucose levels thatcannot be provided by fat. Breakdown of glycogen involves 1) release of glucose-1-phosphate (G1P), 2) rearranging the remaining glycogen (as necessary) to permit continued breakdown, and 3) conversion of G1P to G6P for further metabolism. Remember that G6P can be Continue reading >>

Carbohydrate Metabolism

Carbohydrate metabolism denotes the various biochemical processes responsible for the formation, breakdown, and interconversion of carbohydrates in living organisms. Carbohydrates are central to many essential metabolic pathways.[1] Plants synthesize carbohydrates from carbon dioxide and water through photosynthesis, allowing them to store energy absorbed from sunlight internally.[2] When animals and fungi consume plants, they use cellular respiration to break down these stored carbohydrates to make energy available to cells.[2] Both animals and plants temporarily store the released energy in the form of high energy molecules, such as ATP, for use in various cellular processes.[3] Although humans consume a variety of carbohydrates, digestion breaks down complex carbohydrates into a few simple monomers for metabolism: glucose, fructose, and galactose.[4] Glucose constitutes about 80% of the products, and is the primary structure that is distributed to cells in the tissues, where it is broken down or stored as glycogen.[3][4] In aerobic respiration, the main form of cellular respiration used by humans, glucose and oxygen are metabolized to release energy, with carbon dioxide and water as byproducts.[2] Most of the fructose and galactose travel to the liver, where they can be converted to glucose.[4] Some simple carbohydrates have their own enzymatic oxidation pathways, as do only a few of the more complex carbohydrates. The disaccharide lactose, for instance, requires the enzyme lactase to be broken into its monosaccharide components, glucose and galactose.[5] Metabolic pathways[edit] Overview of connections between metabolic processes. Glycolysis[edit] Glycolysis is the process of breaking down a glucose molecule into two pyruvate molecules, while storing energy released Continue reading >>

Energy Metabolism In The Liver

Go to: Introduction The liver is a key metabolic organ which governs body energy metabolism. It acts as a hub to metabolically connect to various tissues, including skeletal muscle and adipose tissue. Food is digested in the gastrointestinal (GI) tract, and glucose, fatty acids, and amino acids are absorbed into the bloodstream and transported to the liver through the portal vein circulation system. In the postprandial state, glucose is condensed into glycogen and/or converted into fatty acids or amino acids in the liver. In hepatocytes, free fatty acids are esterified with glycerol-3-phosphate to generate triacylglycerol (TAG). TAG is stored in lipid droplets in hepatocytes or secreted into the circulation as very low-density lipoprotein (VLDL) particles. Amino acids are metabolized to provide energy or used to synthesize proteins, glucose, and/or other bioactive molecules. In the fasted state or during exercise, fuel substrates (e.g. glucose and TAG) are released from the liver into the circulation and metabolized by muscle, adipose tissue, and other extrahepatic tissues. Adipose tissue produces and releases nonesterified fatty acids (NEFAs) and glycerol via lipolysis. Muscle breaks down glycogen and proteins and releases lactate and alanine. Alanine, lactate, and glycerol are delivered to the liver and used as precursors to synthesize glucose (gluconeogenesis). NEFAs are oxidized in hepatic mitochondria through fatty acid β oxidation and generate ketone bodies (ketogenesis). Liver-generated glucose and ketone bodies provide essential metabolic fuels for extrahepatic tissues during starvation and exercise. Liver energy metabolism is tightly controlled. Multiple nutrient, hormonal, and neuronal signals have been identified to regulate glucose, lipid, and amino acid me Continue reading >>

Bisc 1005 Flashcards | Quizlet

The First Law of Thermodynamics/Law of Conservation of Energy Energy can neither be created nor destroyed by ordinary processes. Energy can be converted from one form to another. When energy is converted from one form to another the amount of useful energy decreases Increase in randomness, disorder, and less useful energy A reaction that releases energy. The reactants contain more energy than the products. A reaction that requires a net input of energy. The products contain more energy than the reactants. The most common energy carrier in the body. A nucleotide composed of the nitrogen containing base adenine, the sugar ribose, and three phosphate groups. An exergonic reaction provides the energy needed to drive an endergonic reaction Pocket in an enzyme where substrates enter A substance that is not an enzyme's normal substrate can bind to its active site, competing with the substrate for the active site A molecule binds to a site on an enzyme that is distinct from its active site resulting in the distortion of the active site, making the enzyme less capable of catalyzing the reaction An enzyme loses the exact three-dimensional structure required for it to function properly Splits the six-carbon glucose molecule into two molecules of pyruvate Breaks down the two pyruvate molecules from glycolysis into six carbon dioxide molecules and six water molecules as well as 32 ATP For each Acetyl CoA, it produces two CO2, one ATP, three NADH, and one FADH2 The process by which energy is used to generate a concentration gradient of H+ Second stage of glucose breakdown under anaerobic conditions. Pyruvate is converted into either lactate or ethanol and CO2. Required to convert NADH back to NAD+ which needs to be available for glycolysis to continue Lactate converted back into pyr Continue reading >>

Glycogenesis, Glycogenolysis,

Biosynthesis of Glycogen: The goal of glycolysis, glycogenolysis, and the citric acid cycle is to conserve energy as ATP from the catabolism of carbohydrates. If the cells have sufficient supplies of ATP, then these pathways and cycles are inhibited. Under these conditions of excess ATP, the liver will attempt to convert a variety of excess molecules into glucose and/or glycogen. Glycogenesis: Glycogenesis is the formation of glycogen from glucose. Glycogen is synthesized depending on the demand for glucose and ATP (energy). If both are present in relatively high amounts, then the excess of insulin promotes the glucose conversion into glycogen for storage in liver and muscle cells. In the synthesis of glycogen, one ATP is required per glucose incorporated into the polymeric branched structure of glycogen. actually, glucose-6-phosphate is the cross-roads compound. Glucose-6-phosphate is synthesized directly from glucose or as the end product of gluconeogenesis. Link to: Interactive Glycogenesis (move cursor over arrows) Jim Hardy, Professor of Chemistry, The University of Akron. Glycogenolysis: In glycogenolysis, glycogen stored in the liver and muscles, is converted first to glucose-1- phosphate and then into glucose-6-phosphate. Two hormones which control glycogenolysis are a peptide, glucagon from the pancreas and epinephrine from the adrenal glands. Glucagon is released from the pancreas in response to low blood glucose and epinephrine is released in response to a threat or stress. Both hormones act upon enzymes to stimulate glycogen phosphorylase to begin glycogenolysis and inhibit glycogen synthetase (to stop glycogenesis). Glycogen is a highly branched polymeric structure containing glucose as the basic monomer. First individual glucose molecules are hydrolyzed fr Continue reading >>

Which Metabolic Process Refers To The Breakdown Of Glycogen To Glucose?

Which metabolic process refers to the breakdown of glycogen to glucose? Which metabolic process refers to the breakdown of glycogen to glucose? [center][color=gray]Please [b]login or register[/b] to leave a reply[/color][/center] Biology Forums - Study Force is the leading provider of online homework help for college and high school students. Get homework help and answers to your toughest questions in biology, chemistry, physics, math, calculus, engineering, accounting, English, writing help, business, humanities, and more. Master your assignments with step-by-step solutions to countless homework questions asked and answered by our members. If we don't have your question, dont worry. You can ask any homework question and get expert homework help in as little as two hours. Our extensive online study community is made up of college and high school students, teachers, professors, parents and subject enthusiasts who contribute to our vast collection of study resources: textbook solutions, study guides, practice tests, practice problems, lecture notes, equation sheets and more. With our help, your homework will never be the same! Continue reading >>

Metabolic States Of The Body

The Absorptive State The absorptive state, or the fed state, occurs after a meal when your body is digesting the food and absorbing the nutrients (catabolism exceeds anabolism). Digestion begins the moment you put food into your mouth, as the food is broken down into its constituent parts to be absorbed through the intestine. The digestion of carbohydrates begins in the mouth, whereas the digestion of proteins and fats begins in the stomach and small intestine. The constituent parts of these carbohydrates, fats, and proteins are transported across the intestinal wall and enter the bloodstream (sugars and amino acids) or the lymphatic system (fats). From the intestines, these systems transport them to the liver, adipose tissue, or muscle cells that will process and use, or store, the energy. Depending on the amounts and types of nutrients ingested, the absorptive state can linger for up to 4 hours. The ingestion of food and the rise of glucose concentrations in the bloodstream stimulate pancreatic beta cells to release insulin into the bloodstream, where it initiates the absorption of blood glucose by liver hepatocytes, and by adipose and muscle cells. Once inside these cells, glucose is immediately converted into glucose-6-phosphate. By doing this, a concentration gradient is established where glucose levels are higher in the blood than in the cells. This allows for glucose to continue moving from the blood to the cells where it is needed. Insulin also stimulates the storage of glucose as glycogen in the liver and muscle cells where it can be used for later energy needs of the body. Insulin also promotes the synthesis of protein in muscle. As you will see, muscle protein can be catabolized and used as fuel in times of starvation. If energy is exerted shortly after eatin Continue reading >>

Fn Ch. 8 Flashcards | Quizlet

The sum of all chemical reactions in the body metabolism takes place within cells. The powerhouse of the cell is the which bond is the source of a large amount of energy in reactions involving ATP? the breaking of one phosphate bond (forming adp) the only source of energy that can be used directly by the cells is The first step in forming ATP from glucose is The primary pathway to metabolize low volumes of alcohol is the alcohol dehydrogenase (ADH) enzyme system Genetic disorders of metabolism are problematic because they lead to Which of the following is an anabolic reaction? The most metabolically active organ in the body is the Excess carbohydrates in the diet are first stored as Which metabolic process refers to the breakdown of glycogen to glucose? Which metabolic process refers to the production of glucose from noncarbohydrate sources? T/F: Beta-oxidation is a series of metabolic reactions in which amino acids are oxidized to acetyl CoA. FALSE: Beta-oxidation is a metabolic process whereby fatty acids are broken down into acetyl-CoA T/F: Glycolysis involves the conversion of glucose to acetyl CoA. False: the breakdown of glucose;for each molecule of glucose, two molecules of pyruvate and two atp molecules are produced. Which molecule is considered the "gateway" for aerobic metabolism? Continue reading >>

Metabolism And Energetics

Metabolism basically refers to all the chemical reactions within the body used to produce energy. This involves a complex set of processes that convert fuels into specialised compounds loaded with energy. In the body, the primary final agent to produce energy is called adenosine triphosphate (ATP) . When ATP is broken down or used by cells huge amounts of energy is released. This energy is essential for cells to grow and divide, synthesise important compounds, for muscles to contract and numerous other important functions. Metabolism therefore produces energy to perform all the functions of different tissues within the body. Metabolism works by breaking down foods in the diet or compounds in the body into their smaller components. These can then enter into special reactions to produce ATP. The left over components are recycled by the body and used to regenerate the original compounds. The body has three main types of molecules it uses for energy: Carbohydrates: These are the sugar type compounds in the body. Carbohydrates come from foods such as bread, cereal, potatoes, fruits and sugar-containing foods or bevarages. When carbohydrates are digested in the gastrointestinal system they are broken down into smaller molecules such as glucose (a simple sugar). The main storage sites for carbohydrates in the body are the liver and muscles. Lipids: This basically refers to fats (such as cholesterol) from the diet or stored in adipose tissue (in other words the body fat). Lipids are broken down into smaller components called fatty acids for energy. Therefore lipids are really just chains of fatty acids joined together. Proteins: These make up nearly three quarters of all the solid materials in the body. Proteins are thus the basic structural components in the body. They are ma Continue reading >>

Fshn 265- Exam 3 Flashcards | Quizlet

Which metabolic process refers to the breakdown of glycogen to glucose Excess carbohydrates in the diet are first stored as Fatty acids are cleaved from the glycerol backbone during digestion to yield free fatty acids in a process called The formation of glucose from noncarbohydrate sources, such as glucogenic amino acids, is called The process of converting excess glucose to glycogen in the liver and muscle is referred to as The process in which glucose is broken down to produce energy is called is the process that converts excess glucose or amino acids into fatty acids to be stored as triglycerides in the adipose cells. carbohydrate metabolism during the postabsorptive state Muscle glycogen stores are depleted early in the postabsorptive state. Glycogen stores are used during short periods of fasting overnight or between meals. These stores are depleted early when fasting becomes prolonged. protein metabolism during the postabsorptive state Amino acids are used to produce glucose through gluconeogenesis during the postabsorptive state. lipid metabolism during the postabsorptive state F.A. rapidly broken down from adipose tissues and converted to ketone bodies glycolosis-acetyl coa-TCA cycle-Electron Transport Chain-Oxidative Phosporylation benefit endurance athletes. replaces water and electrolytes. Glucose facilitates electrolyte absorption. not idea! does not restore electrolytes and glycogen stores measure calories in foods in terms of heat. burn hotter=more calories what keeps us alive, and heart pumping. depends on many factors; age, gender, body size, genes, ethnicity, nutritional state energy to digest food. protein has highest thermic effect because it require ATP to get absorbed. Obese individuals have a lower thermic effect due to less muscle mass. thermal Continue reading >>

Regulation Of Glycolysis And Gluconeogenesis

- [Instructor] At its most simplistic level, regulation of metabolic pathways inside of the body is really just a fancy word for a balancing act that's occurring in the body. So, to illustrate this, I have a seesaw and we've been learning about two metabolic pathways: glycolysis, which is the process of breaking down glucose into pyruvate; and gluconeogenesis, which is essentially the opposite in which we start out with pyruvate and through a little bit of a different route we end up back at glucose. And when we're talking about the regulation of these particular pathways, we're essentially asking ourself, "When is glycolysis the predominant pathway and when is gluconeogenesis the predominant pathway?" The body wants to make sure that we either have a net breakdown of glucose, in the case of glycolysis, or that we have a net production of glucose, in the case of gluconeogenesis. So now the next question is, "How does the body "accomplish this balancing act?" And to answer this question, the way I like to think about it is to think about it along a spectrum. There are very fast-acting forms of regulation that take place on the order of seconds, and there are very very slow forms of regulation that can take up to hours or even days to occur. So let's talk about each of these in a little bit more detail. The major principle that helps me understand fast-acting forms of regulation is a good old principle from general chemistry: Le Chatelier's Principle. So if you remember, Le Chatelier's Principle talks about anything that's in equilibrium and it says that if there's any change to this equilibrium, let's say more products are added or reactants are taken away, the equilibrium will adjust to essentially counter that change and return the system back to equilibrium. So what d Continue reading >>

Glycogenolysis | Biochemistry | Britannica.com

Glycogenolysis, process by which glycogen , the primary carbohydrate stored in the liver and muscle cells of animals, is broken down into glucose to provide immediate energy and to maintain blood glucose levels during fasting . Glycogenolysis occurs primarily in the liver and is stimulated by the hormones glucagon and epinephrine (adrenaline). Various enzyme defects can prevent the release of energy by the normal breakdown of glycogen in muscles. Enzymes in which defects may occur include glucose-6-phosphatase (I); lysosomal x-1,4-glucosidase (II); debranching enzyme (III); branching enzyme (IV); muscle phosphorylase (V); liver phosphorylase (VI, VIII, IX, X); and muscle phosphofructokinase (VII). Enzyme defects that can give rise to other carbohydrate diseases include galactokinase (A1); galactose 1-phosphate UDP transferase (A2); fructokinase (B); aldolase (C); fructose 1,6-diphosphatase deficiency (D); pyruvate dehydrogenase complex (E); and pyruvate carboxylase (F). When blood glucose levels fall, as during fasting, there is an increase in glucagon secretion from the pancreas . That increase is accompanied by a concomitant decrease in insulin secretion, because the actions of insulin, which are aimed at increasing the storage of glucose in the form of glycogen in cells, oppose the actions of glucagon. Following secretion, glucagon travels to the liver, where it stimulates glycogenolysis. The vast majority of glucose that is released from glycogen comes from glucose-1-phosphate, which is formed when the enzyme glycogen phosphorylase catalyzes the breakdown of the glycogen polymer . In the liver, kidneys , and intestines , glucose-1-phosphate is converted (reversibly) to glucose-6-phosphate by the enzyme phosphoglucomutase. Those tissues also house the enzyme glucose Continue reading >>

Metabolism And Energetics

Metabolism basically refers to all the chemical reactions within the body used to produce energy. This involves a complex set of processes that convert fuels into specialised compounds loaded with energy. In the body, the primary final agent to produce energy is called adenosine triphosphate (ATP) . When ATP is broken down or used by cells huge amounts of energy is released. This energy is essential for cells to grow and divide, synthesise important compounds, for muscles to contract and numerous other important functions. Metabolism therefore produces energy to perform all the functions of different tissues within the body. Metabolism works by breaking down foods in the diet or compounds in the body into their smaller components. These can then enter into special reactions to produce ATP. The left over components are recycled by the body and used to regenerate the original compounds. The body has three main types of molecules it uses for energy: Carbohydrates: These are the sugar type compounds in the body. Carbohydrates come from foods such as bread, cereal, potatoes, fruits and sugar-containing foods or bevarages. When carbohydrates are digested in the gastrointestinal system they are broken down into smaller molecules such as glucose (a simple sugar). The main storage sites for carbohydrates in the body are the liver and muscles. Lipids: This basically refers to fats (such as cholesterol) from the diet or stored in adipose tissue (in other words the body fat). Lipids are broken down into smaller components called fatty acids for energy. Therefore lipids are really just chains of fatty acids joined together. Proteins: These make up nearly three quarters of all the solid materials in the body. Proteins are thus the basic structural components in the body. They are ma Continue reading >>