Nutrition Ch. 7
Front Back .Wirisformula{ margin:0 !important; padding:0 !important; vertical-align:top !important;} Metabolism The sum total of all the chemcial reactions that go on in living cells. Energy metabolism includes all the reactions by which the body obtains and spends energy from food. Example: Nutrients provide the body with FUEL and follows them through a series of reactions that release energy from their chemical bonds. As the bonds break, they release energy in a controlled version of the process by which wood burns in a fire. Energy metabolism All of the chemical reactions through which the human body acquires and spends energy from food Anabolism Small compounds joined together to make largers ones; energy must be used in order to do this Ana = up Catabolism Larger compounds BROKEN down into smaller ones; energy is RELEASED kata = down Coupled reactions Energy released from the breakdown of a large compounds is used to drive other reactions ATP Adenosine triphosphate; energy currency of the body -- produced when large compounds are broken down ATP is used to make large compounds from smaller ones. Ribosomes Cellular machinery used to make proteins Mitochondria Where energy is derived from fat, CHO, protein via TCA cycle, electron transport chain Coenzyme Complex organic molecules that work with enzymes to facilitate the enzymes' activity. Many coenzymes have B vitamins as part of their structures. co = with Cofactor The general term for substances that facilitate enzyme action is cofactors; they include both organic coenzymes such as vitamins and inorganic substances such as minerals Enzymes Protein catalysts - proteins that facilitate chemical reactions without being changed in the process Metalloenzyme Enzymes that contain one or more minerals as part of their stru Continue reading >>
Can Amino Acids Be Used By The Body To Make Glucose & Fatty Acids?
Amino acids are nitrogen-containing molecules that are the building blocks of all proteins in food and in the body. They can be used as energy, yielding about 4 calories per gram, but their primary purpose is the synthesis and maintenance of body proteins including, but not limited to, muscle mass. Video of the Day During normal protein metabolism, a certain number of amino acids are pushed aside each day. When these amino acids are disproportionate to other amino acids for the synthesis of new protein, your liver and kidneys dispose of the nitrogen as urea, and the rest of the molecule is used as energy in a variety of ways. Then certain amino acids -- minus their nitrogen -- can enter the citric acid cycle -- the biochemical pathway that converts food into energy. Others can be converted to glucose or fat. This process may be enhanced when you take in more protein than you need. Your body relies on a continuous supply of glucose and fatty acids for energy for physical activity and cellular needs during rest. When you exercise, your body relies still more on glucose because fat is slower to metabolize. The higher your exercise intensity is, the more your body requires quicker-burning glucose. Some glucose is stored as glycogen in the liver and muscles and can be recruited when blood glucose is used up. When glycogen becomes depleted, the process of gluconeogenesis can take over -- the creation of new glucose from another source. The usual source for gluconeogenesis is amino acids. Healthy people store adequate body fat to cover their energy needs. Although certain amino acids can be converted to fatty acids, there should be no need for this to occur in order to supply energy. But if a very high protein intake adds substantially more calories, theoretically those extra Continue reading >>
Chapter 7
Metabolism: Transformations and Interactions Chemical Reactions in the Body Plants use the sun’s energy to make carbohydrate from carbon dioxide and water. This is called photosynthesis. Humans and animals eat the plants and use the carbohydrate as fuel for their bodies. During digestion, the energy-yielding nutrients are broken down to monosaccharides, fatty acids, glycerol, and amino acids. After absorption, enzymes and coenzymes can build more complex compounds. In metabolism they are broken down further into energy (ATP), water and carbon dioxide. Chemical Reactions in the Body Metabolic reactions take place inside of cells, especially liver cells. Anabolism is the building up of body compounds and requires energy. Catabolism is the breakdown of body compounds and releases energy. Chemical Reactions in the Body Enzymes and coenzymes are helpers in reactions. Enzymes are protein catalysts that cause chemical reactions. Coenzymes are organic molecules that function as enzyme helpers. Cofactors are organic or inorganic substances that facilitate enzyme action. Breaking Down Nutrients for Energy The breakdown of glucose to energy starts with glycolysis to pyruvate. Pyruvate may be converted to lactic acid anaerobically (without oxygen) and acetyl CoA aerobically (with oxygen). Eventually, all energy-yielding nutrients enter the TCA cycle or tricarboxylic acid cycle (or Kreb’s cycle) and the electron transport chain. Breaking Down Nutrients for Energy Glucose Glucose-to-pyruvate is called glycolysis or glucose splitting. Pyruvate’s Options Anaerobic – lactic acid Aerobic – acetyl CoA Pyruvate-to-Lactate Oxygen is not available or cells lack sufficient mitochondria Lactate is formed when hydrogen is added to pyruvate. Liver cells recycle Continue reading >>
Connections Between Cellular Respiration And Other Pathways
So far, we’ve spent a lot of time describing the pathways used to break down glucose. When you sit down for lunch, you might have a turkey sandwich, a veggie burger, or a salad, but you’re probably not going to dig in to a bowl of pure glucose. How, then, are the other components of food – such as proteins, lipids, and non-glucose carbohydrates – broken down to generate ATP? As it turns out, the cellular respiration pathways we’ve already seen are central to the extraction of energy from all these different molecules. Amino acids, lipids, and other carbohydrates can be converted to various intermediates of glycolysis and the citric acid cycle, allowing them to slip into the cellular respiration pathway through a multitude of side doors. Once these molecules enter the pathway, it makes no difference where they came from: they’ll simply go through the remaining steps, yielding NADH, FADH, and ATP. Simplified image of cellular respiration pathways, showing the different stages at which various types of molecules can enter. Glycolysis: Sugars, glycerol from fats, and some types of amino acids can enter cellular respiration during glycolysis. Pyruvate oxidation: Some types of amino acids can enter as pyruvate. Citric acid cycle: Fatty acids from fats and certain types of amino acids can enter as acetyl CoA, and other types of amino acids can enter as citric acid cycle intermediates. In addition, not every molecule that enters cellular respiration will complete the entire pathway. Just as various types of molecules can feed into cellular respiration through different intermediates, so intermediates of glycolysis and the citric acid cycle may be removed at various stages and used to make other molecules. For instance, many intermediates of glycolysis and the cit Continue reading >>
Amino Acid Metabolism!
Our current examination of proteins and amino acids will cover the metabolism of the protein we eat, dietary protein, and catabolic situations in the body. Amino acids are the "building-blocks" of proteins. Proteins, from the Greek word meaning "of prime importance," constitute an array of structures. Examples of these structures include hormones, enzymes, and muscle tissue. The primary function of protein is growth and repair of body tissue (anabolism). Proteins can also be used as energy through catabolic (breakdown of tissues) reactions, such as gluconeogenesis-the process of making glucose from amino acids, lactate, glycerol, or pyruvate in the liver or kidneys. Our current examination of proteins and amino acids will cover the metabolism of the protein we eat, dietary protein, and catabolic situations in the body. A general understanding of the molecular structure of proteins and amino acids is needed to understand their metabolism. Protein is comprised of carbon, hydrogen, oxygen and, most importantly, nitrogen. Protein may also contain sulfur, cobalt, iron, and phosphorus. These elements form the "building blocks" of protein, amino acids . A protein molecule is made up of long chains of amino acids bonded to each other by amide bonds, or peptide linkages. The food (protein) we eat contains different amino acids depending on the type of amino acids present. An almost endless combination of amino acid bonds can exist. The combination of amino acids governs the protein's properties. Just as the combination of amino acids governs the specific proteins properties, the structure of individual amino acids determines its function in the body. An amino acid is made up of a central carbon atom, a positively charged amine group (NH2) at one end and a negatively charged car Continue reading >>
Gluconeogenesis
Not to be confused with Glycogenesis or Glyceroneogenesis. Simplified Gluconeogenesis Pathway Gluconeogenesis (GNG) is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. From breakdown of proteins, these substrates include glucogenic amino acids (although not ketogenic amino acids); from breakdown of lipids (such as triglycerides), they include glycerol (although not fatty acids); and from other steps in metabolism they include pyruvate and lactate. Gluconeogenesis is one of several main mechanisms used by humans and many other animals to maintain blood glucose levels, avoiding low levels (hypoglycemia). Other means include the degradation of glycogen (glycogenolysis)[1] and fatty acid catabolism. Gluconeogenesis is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms.[2] In vertebrates, gluconeogenesis takes place mainly in the liver and, to a lesser extent, in the cortex of the kidneys. In ruminants, this tends to be a continuous process.[3] In many other animals, the process occurs during periods of fasting, starvation, low-carbohydrate diets, or intense exercise. The process is highly endergonic until it is coupled to the hydrolysis of ATP or GTP, effectively making the process exergonic. For example, the pathway leading from pyruvate to glucose-6-phosphate requires 4 molecules of ATP and 2 molecules of GTP to proceed spontaneously. Gluconeogenesis is often associated with ketosis. Gluconeogenesis is also a target of therapy for type 2 diabetes, such as the antidiabetic drug, metformin, which inhibits glucose formation and stimulates glucose uptake by cells.[4] In ruminants, because dietary carbohydrates tend to be metabolized by rumen organisms, gluconeogenesis occurs Continue reading >>
Proteins For Energy
You have seen how proteins can be built up from amino acids with a particular primary,secondary, tertiary and even quaternary structure to serve particular functions. If theproteins are damaged, or for some reason are no longer needed or no longer able to servethose functions, the proteins can be broken down by hydrolysis reactions to reform theamino acids from which they were made. In the body this hydrolysis process is catalyzed byenzymes. Yes, enzymes are proteins which can catalyze the hydrolysis of other proteins. Strong acids or bases can also catalyze the hydrolysis reaction of protein both outsideand unfortunately sometimes inside the body. This is what happens if you were to spill astrong acid or base on your skin or accidentally ingest it. They will cause the hydrolysisof the protein and thus break it down. The amino acids that are formed by the hydrolysis of protein can be used tomake new protein or they can have their amino groups removed and then theremainder of the molecule can be oxidized to provide energy. These altered (deaminated) amino acids enter the citric acid cycle in a variety of ways but once they have done so, the result is the formation of carbon dioxide and the release of hydrogen with electrons that combine with oxygen to form water. With that, of course, comes the release of energy. Some amino acids are converted to pyruvate or pyruvic acid. Some are converted into acetyl CoA. Others are converted into acetyl CoA through a previous step of acetoacetyl CoA. Some are converted into one of the chemicals in the cycle, oxaloacetate. Others are converted to other chemicals that are a part of the citric acid cycle. The nitrogen that is removed from the amino acids in this process is ultimately converted to urea and excreted in the urine. Whatever Continue reading >>
The Catabolism Of Fats And Proteins For Energy
Before we get into anything, what does the word catabolism mean? When we went over catabolic and anabolic reactions, we said that catabolic reactions are the ones that break apart molecules. To remember what catabolic means, think of a CATastrophe where things are falling apart and breaking apart. You could also remember cats that tear apart your furniture. In order to make ATP for energy, the body breaks down mostly carbs, some fats and very small amounts of protein. Carbs are the go-to food, the favorite food that cells use to make ATP but now we’re going to see how our cells use fats and proteins for energy. What we’re going to find is that they are ALL going to be turned into sugars (acetyl) as this picture below shows. First let’s do a quick review of things you already know because it is assumed you learned cell respiration already and how glucose levels are regulated in your blood! Glucose can be stored as glycogen through a process known as glycogenesis. The hormone that promotes this process is insulin. Then when glycogen needs to be broken down, the hormone glucagon, promotes glycogenolysis (Glycogen-o-lysis) to break apart the glycogen and increase the blood sugar level. Glucose breaks down to form phosphoglycerate (PGAL) and then pyruvic acid. What do we call this process of splitting glucose into two pyruvic sugars? That’s glycolysis (glyco=glucose, and -lysis is to break down). When there’s not enough oxygen, pyruvic acid is converted into lactic acid. When oxygen becomes available, lactic acid is converted back to pyruvic acid. Remember that this all occurs in the cytoplasm. The pyruvates are then, aerobically, broken apart in the mitochondria into Acetyl-CoA. The acetyl sugars are put into the Krebs citric acid cycle and they are totally broken Continue reading >>
Can Amino Acids Be Used By The Body To Make Glucose Fatty Acids - Things You Didn't Know
Can amino acids be used by the body to make glucose fatty acids? Your body wilk:Break down anything and everything it can into basic building blocks and then metabolize them for calories and energy, store them away or use them to manufacture something like carbohydrates, proteins, fats or anything and everything else. There's nothing special about Amino Acids - they're just building blocks that will be broken down like everything else. ...Read more The blood sugar concentration or blood glucose level is the amount of glucose (sugar) present in the blood of a human or animal. The body naturally tightly regulates blood glucose levels as a part of metabolic homeostasis. Glucose is the primary source of energy for the body's cells, and blood lipids (in the form of fats and oils) are primarily a compact energy store. ...Read more No:We all take amino acids in our diet . Proteins are made of amino acids and proteins are present in grains, legumes, beans, nuts, milk etc. There is no substitute to reducing caloric intake and increasing physical activity. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, low fat milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco or alcohol in any form. Continue reading >>
Chapter 7
Sort What is the difference between energy and metabolism? Energy metabolism? Energy is the capacity to do work - heat, mechanical, electrical, CHEMICAL Metabolism is how the body uses food to meet its needs - specifically, it is the sum total of all chemical reactions in the living cells of the body - energy metabolism includes all reactions by which the body obtains and expends the energy from food What are the two types of metabolic reactions in the body? Anabolic/Anabolism - building body compounds (requires energy) - ex. glucose + glucose = glycogen - ex. glycerol + fatty acid = triglycerides - ex. amino acid + amino acid = protein Catabolic/Catabolism - breaking down body compounds (releases energy) - ex. glycogen -> glucose - ex. triglycerides -> glycerol + fatty acid - ex. protein -> amino acids What is ATP? How is it formed? (adenosine triphosphate) It is a molecule made up of three phosphate groups that has high energy bonds (so it provides lots of energy when it is broken down) - it is what provides energy for any reaction or cell activity in the body It is formed from the breakdown of glucose (glycolysis), fatty acids, and amino acids Its negative charge makes it vulnerable to hydrolysis What is the idea of coupled reactions? The body makes ATP in coupled reactions. Energy (ATP) is needed to facilitate the reactions that make more ATP. So the body uses ATP to make ATP 1.) ATP is broken down, which provides energy for a variety of functions in the body - when ATP is broken down, it loses a phosphate group and becomes ADP 2.) Energy is required to add a phosphate group to ADP to make ATP (uses ATP from food to do this) This system is about 50% efficient, and the rest is lost as heat How does digestion break things down into smaller units? Carbs -> glucose (and Continue reading >>
Lecture 6: Proteins And Amino Acids- Set 3
making proteins from RNA; tRNA translates the mRNA code into a sequence of amino acids. something wrong in a protein, like an enzyme the process whereby the information coded in a gene is used to produce a protein, and is based on the need for the given protein. the essential amino acid that is available in the lowest concentration in relation to the body's need. -this limits the body's ability to synthesize a protein Name some nonprotein molecules that amino acids are used to make? DNA, RNA, and neurotransmitters (all N containing) What happens to the amino group once it is removed from the amino acid? It is converted into ammonia. Ammonia enters the liver and is converted to urea which goes to the kidneys for removal. After deamination, what must happen to the amino acid before it can be used for energy? The remaining carbon skeleton can be broken down to produce ATP or used to make glucose or fatty acids. It can enter at different points of the citric acid cycle, and then enters electron transport chain Breaking up amino acids is metabolically expensive. What does this mean? It takes up more energy to break these down than fat or carbs What happens to body proteins when energy is low? , body proteins, such as enzymes and muscle proteins, are broken down into amino acids that can then be used to generate ATP or synthesize glucose. Proteins provide structure at the cellular level as an integral component of cell membranes. protein molecules that speed up metabolic reactions but are not used up or destroyed in the process. chemical messengers that are secreted into the blood and act on target cells in other parts of the body Proteins that transport substances into and out of individual cells and throughout the body. (inclues lipoproteins, which carry lipids around the Continue reading >>
Glucogenic Amino Acids
DOUGLAS C. HEIMBURGER MD, in Handbook of Clinical Nutrition (Fourth Edition) , 2006 The major aim of protein catabolism during a state of starvation is to provide the glucogenic amino acids (especially alanine and glutamine) that serve as substrates for endogenous glucose production (gluconeogenesis) in the liver. In the hypometabolic/starved state, protein breakdown for gluconeogenesis is minimized, especially as ketones become the substrate preferred by certain tissues. In the hypermetabolic/stress state, gluconeogenesis increases dramatically and in proportion to the degree of the insult to increase the supply of glucose (the major fuel of reparation). Glucose is the only fuel that can be utilized by hypoxic tissues (anaerobic glycolysis), by phagocytosing (bacteria-killing) white cells, and by young fibroblasts. Infusions of glucose partially offset a negative energy balance but do not significantly suppress the high rates of gluconeogenesis in the catabolic patient. Hence, adequate supplies of protein are needed to replace the amino acids utilized for this metabolic response. In summary, the two physiologic states represent different responses to starvation. The hypometabolic patient, who conserves body mass by reducing the metabolic rate and using fat as the primary fuel (rather than glucose and its precursor amino acids), is adapted to starvation. The hypermetabolic patient also uses fat as a fuel but rapidly breaks down body protein to produce glucose, the fuel of reparation, thereby causing loss of muscle and organ tissue and endangering vital body functions. Joerg Klepper*, in Handbook of Clinical Neurology , 2013 Gluconeogenesis, predominantly in the liver, generates glucose from noncarbohydrate substrates such as lactate, glycerol, and glucogenic amino acid Continue reading >>
Hs-350- Ch.7 Flashcards | Quizlet
Chemical reactions that take place in the body Chemical reactions that enable cells to store and use energy from nutrients (refers to hundreds of chemical reactions involved in the breakdown, synthesis and transformation of the energy yielding nutrients glucose amino acids and fatty acids that enable the body to store and use energy) A series of interrelated enzyme-catalyzed chemical reactions that take place in cells A molecule that enters a chemical reaction (also called a reactant) A molecule produced in a chemical reaction A product formed before a metabolic pathway reaches completion often serving as a substrate in the next chemical reaction Genetic condition caused by a deficiency or absence of one or more enzymes needed for a metabolic pathway to function properly (also called inborn error of metabolism) A series of metabolic reactions that break down a complex molecule into simpler ones, often releasing energy in the process A series of metabolic reactions that require energy to make a complex molecule from simple one, often requiring energy in the process Metabolic pathway that generates intermediate products that can be used for both catabolism and anabolism Biological catalyst that facilitate chemical reactions (increase rate of reactions without changing the enzyme) An area on an enzyme that binds substrates in a chemical reaction (shape of site changes to fit the shape of substrate) A substrate attached to an enzymes active site (inorganic substance such as Z, K, Fe, Mg) Organic molecule, often derived from vitamin, needed for some enzymes to function (example NAD, FAD & NADP) The oxidized form of the coenzyme that is able to accept two electrons and two hydrogen ions, forming NADH + H+ The oxidized form of the coenzyme that is able to accept two electrons 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 >>
Energy Metabolism
Sort Electron Transport Chain The electron transport chain is the final pathway in energy metabolism that transports electrons from hydrogen to oxygen and captures the energy released in the bonds of ATP (respiratory chain). The electron transport chain captures energy in the high-energy bonds of ATP. The electron transport chain consists of a series of proteins that serve as electron "carriers." These carriers are mounted in sequence on the inner membrane of the mitochondria. The electron carriers pass the electrons down until they reach oxygen. Oxygen accepts the electrons and combines with hydrogen atoms to form water. Oxygen must be available for energy metabolism. As electrons are passed from carrier to carrier, hydrogen ions are pumped across the membrane to the outer compartment of the mitochondria. The rush of hydrogen ions back into the inner compartment powers the synthesis of ATP (energy is captured in the bonds of ATP). The ATP leaves the mitochondria and enters the cytoplasm, where it can be used for energy. Anaerobic When the body needs energy quickly, pyruvate is converted to lactate. The breakdown of glucose-to-pyruvate-to-lactate proceeds without oxygen-it is anaerobic. This anaerobic pathway yields energy quickly, but it cannot be sustained for long. Coenzymes carry the hydrogens from glucose breakdown to the electron transport chain. If the electron transport chain is unable to accept the hydrogens, as may occur when cells lack sufficient mitochondria or in the absence of oxygen, pyruvate can accept the hydrogens. By accepting the hydrogens, pyruvate becomes lactate, and the coenzymes are freed to return to glycolysis to pick up more hydrogens. In this way, glucose can continue provided energy anaerobically for a while. One possible fate of the lactat Continue reading >>
