...N C E Review in Advance first posted online on May 11, 2012. (Changes may still occur before final publication online and in print.) S I N Driving the Cell Cycle Through Metabolism Ling Cai and Benjamin P. Tu Annu. Rev. Cell Dev. Biol. 2012.28. Downloaded from www.annualreviews.org by Ecole Polytechnique Federal Lausanne on 06/20/12. For personal use only. Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038; email: benjamin.tu@utsouthwestern.edu Annu. Rev. Cell Dev. Biol. 2012. 28:3.1–3.29 The Annual Review of Cell and Developmental Biology is online at cellbio.annualreviews.org This article’s doi: 10.1146/annurev-cellbio-092910-154010 Copyright c 2012 by Annual Reviews. All rights reserved 1081-0706/12/1110-0001$20.00 Keywords cell growth, cell proliferation, metabolic cycle, growth control, nutrients, yeast Abstract For unicellular organisms, the decision to enter the cell cycle can be viewed most fundamentally as a metabolic problem. A cell must assess its nutritional and metabolic status to ensure it can synthesize sufficient biomass to produce a new daughter cell. The cell must then direct the appropriate metabolic outputs to ensure completion of the division process. Herein, we discuss the changes in metabolism that accompany entry to, and exit from, the cell cycle for the unicellular eukaryote Saccharomyces cerevisiae. Studies of budding yeast under continuous, slow-growth conditions have provided...
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...PMB 103: METABOLISM: BASIC CONCEPTS AND DESIGN Definition of terms; metabolism, bioenergetics and thermodynamics. * Laws of thermodynamics, free energy changes and standard free energy changes in biochemical reactions. * Phosphoryl group transfers and ATP; * Free-energy change for hydrolysis of ATP and other phosphorylated compounds and thioesters. * Role of ATP: phosphorylation, * pyrophosphorylation and adenylation, * assembly of informational macromolecules, * active transport and muscle contraction. * Biological oxidation-reduction reactions; * flow of electrons * dehydrogenations * redox potentials * electron carriers * dehydrogenases * Nature of metabolic reactions: anabolism, catabolism. * regulation of metabolism. Scope of the course * (Review) the laws of thermodynamics and the quantitative relationships among free energy, enthalpy, and entropy. * describe the special role of ATP in biological energy exchanges. Consider the importance of oxidation-reduction reactions in living cells, the energetic of electron-transfer reactions, and the electron carriers commonly employed as cofactors of the enzymes that catalyze these reactions. Reference Books 1. Lehninger, PPls of Biochemistry Fourth Edition David L Nelson and 2. Elementary Biophysics. An introduction. PK. Srivastave Alpha Science Oxford, UK 2005 3. Biophysics. V. Pattabhi and N. Gautham. Second Edition...
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...Metabolism . Metabolism refers to the chemical reactions that take place in living organisms. There are two categories for metabolism: ---Catobolism: break down of matter ---Anabolism: build up matter (proteins, nucleic acids) Enzymes are the proteins that breakdown matter in catabolism. (Wikipedia/ metabolism, 2013) How do enzymes work? An enzymes job is to lower the activation energy for a reaction in order to increase it’s rate. (Wikipedia/ enzyme, 2013) Every enzyme has an active site where the substrate binds. Once bound to the enzyme, it breaks sown the substrate and releases it as product. The enzyme remains intact and ready to repeat the process. (Ahern, p.4-6) What happens in inherited fructose intolerance? Aldolase B is the enzyme needed to break down fructose. When someone without aldolase B consumes fructose or sucrose their body cannot change glycogen (energy storage material) to glucose. Because of this the blood sugar levels fall and toxins collect in the liver. This condition is hereditary, meaning that it is passed down from parents whom either exhibit this condition or is a carrier of it. (UMMC, 2011) . . . Fructose-1 phosphate is the substrate that functions in fructose metabolism. Without the activity of adolase B, fructose-1 phosphate rapidly collects in the liver. ...
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...Metabolism Western Governors University Aston Portis 1. All enzymes are catalyst because they cause a chemical reaction to take place faster than it would on its own. It also does not get used during the reaction (Hudon-Miller, 2012). 2. (Hudon-Miller, 2012). 3. (Hudon-Miller, 2012). 4. Fructose is component of sucrose, normal table sugar, along with glucose. Whereas glucose is able to immediately enter into glycolysis, fructose is not. Fructose is broken down via fructokinase into fructose- 1-phosphate. Fructose – 1-phospate then gets converted into DHAP+ glyceraldehyde via aldolase B. DHAP+ glyceraldehyde is used in glycolysis to produce pyruvate that goes into the citric acid cycle to produce ATP (Hudon-Miller, 2012). 5. In aldolase B deficiency the substrate fructose 1- phosphate is unable to produce DHAP+ glyceraldehyde but the fructose is still getting phosphorylated by fructokinase. This causes a buildup of fructose- 1-phosphate. It is not being used in glycolysis or gluconeogenesis. There is a buildup of phosphate which causes the phosphate to get stuck and the free phosphate to be depleted by because of so much is being used by the fructose 1-phosphate. Since our phosphate levels were depleted it slows production of ATP, phosphate is needed in the electron transport chain. Since ATP production has slowed and liver cells are low on energy liver damage can occur which can ultimately lead to liver failure. Fructose-1-phosphate buildup...
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...CARBOHYDRATE METABOLISM Carbohydrates are found as monosaccharides, disaccharides, and polysaccharides or complex carbohydrates. They function in energy storage (starch&glycogen), signaling (glycoproteins and glycolipids, e.g. blood group determinants), fuel the nervous system and muscle (and virtually all cells, although there are distinct cell type specific differences in choice of primary fuel molecule), are parts of nucleic acids (genes, mRNA, tRNA, ribosomes), and as cell surface markers and signaling in glycolipids and glycoproteins, are part of connective tissue (heteropolymers; glycosaminoglycans), cell wall components (cellulose, hemi-cellulose) made of polymers that are enzymatically inert for most mammals to digest (except ruminants that harbor a special digestive tract bacterium with the appropriate cellulase enzyme). The alpha glycosidic bonds found in glycogen and starch is metabolically available to humans. The major source of dietary carbohydrate for humans is starch from consumed plant material. This is supplemented with a small amount of glycogen from animal tissue, disaccharides such as source from products containing refined sugar and lactose in milk. Digestion in the gut converts all carbohydrate to monosaccharides which are transported to the liver and converted to glucose. The liver has central role in the storage anddistribution within the body of all fuels, including glucose. Glucose in the body undergoes one of three metabolic fates. First it...
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...Michelle Stewart Literature Review Landis FN340 30 April 2015 Introduction Fructose, commonly known as fruit sugar, is a major component of sweeteners such as table sugar, honey and high fructose corn syrup (HFCS)1. Fructose is a simple monosaccharide that has been used as a sweetener in food and drinks, and current estimations suggest that sweetener consumption in the U.S. has increased to an average of 477 kcal/person, or approximately 24% of a typical 2000 kcal/day diet2,3. An increase in the consumption of sweeteners containing fructose has occurred in parallel with the increasing prevalence of obesity, suggesting that increased consumption of fructose may contribute to the current epidemic of obesity-related metabolic disorders, including increased incidence of the metabolic syndrome2. The metabolic syndrome (MetS) consists of a syndrome of insulin resistance, dyslipidemia, abdominal obesity, and elevated blood pressure (BP), and often precedes the development of diabetes4. In some studies, humans and animals that have been administered fructose have developed these symptoms, however they have not been observed with glucose or starch-based diets. Fructose and glucose are metabolized quite differently, and it has been hypothesized that this differentiation is the key factor in the development of pathologies associated with MetS5. Additionally, ingestion of fructose does not stimulate the release of the hormones insulin and leptin, nor does it suppress the secretion...
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...CARBOHYDRATE METABOLISM Carbohydrates are found as monosaccharides, disaccharides, and polysaccharides or complex carbohydrates. They function in energy storage (starch&glycogen), signaling (glycoproteins and glycolipids, e.g. blood group determinants), fuel the nervous system and muscle (and virtually all cells, although there are distinct cell type specific differences in choice of primary fuel molecule), are parts of nucleic acids (genes, mRNA, tRNA, ribosomes), and as cell surface markers and signaling in glycolipids and glycoproteins, are part of connective tissue (heteropolymers; glycosaminoglycans), cell wall components (cellulose, hemi-cellulose) made of polymers that are enzymatically inert for most mammals to digest (except ruminants that harbor a special digestive tract bacterium with the appropriate cellulase enzyme). The alpha glycosidic bonds found in glycogen and starch is metabolically available to humans. The major source of dietary carbohydrate for humans is starch from consumed plant material. This is supplemented with a small amount of glycogen from animal tissue, disaccharides such as source from products containing refined sugar and lactose in milk. Digestion in the gut converts all carbohydrate to monosaccharides which are transported to the liver and converted to glucose. The liver has central role in the storage anddistribution within the body of all fuels, including glucose. Glucose in the body undergoes one of three metabolic fates. First it...
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...Protein digestion Protein metabolism denotes the various biochemical processes responsible for the synthesis of proteins and amino acids, and the breakdown of proteins (and other large molecules, too) by catabolism.Dietary proteins are first broken down to individual amino acids by various enzymes and hydrochloric acid present in the gastro-intestinal tract.[1] These amino acids are further broken down to α-keto acids which can be recycled in the body for generation of energy, and production of glucose or fat or other amino acids. This break-down of amino acids to α-keto acids occurs in the liver by a process known as transamination Protein digestion occurs in the stomach and duodenum in which 3 main enzymes, pepsin secreted by the stomach and trypsin and chymotrypsin secreted by the pancreas, break down food proteins into polypeptides that are then broken down by various exopeptidases and dipeptidases into amino acids. The digestive enzymes however are mostly secreted as their inactive precursors, the zymogens. For example, trypsin is secreted by pancreas in the form of trypsinogen, which is activated in the duodenum by enterokinase to form trypsin. Trypsin then cleaves proteins to smaller polypeptides. Protein metabolism is dependent on a vast number of endogenous mediators. These mediators define the balance between anabolic and catabolic processes. Insulin is the major anabolic hormone and also has an important role in amino acid and protein homeostasis. During injury and...
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...Abhishek Makhija (ID: 29740568) Word Count: 1650 (for essay only) Metabolism is understood as a sum of biochemical processes that occur in the body in order to sustain life. An important part of metabolism is a process known as cellular respiration, an enzyme catalysed catabolic process that harvests the energy from food and stored reserves. In the body, this energy is stored as chemical energy in ATP (Adenosine Triphosphate) molecules. Hydrolysis of ATP to its more stable products, ADP and Pi, releases this chemical energy (equivalent to 30.5kJ/mol) which can be used for cellular processes. While a number of macromolecules can produce energy in the form of ATP, the body utilises carbohydrates and lipids (stored as triglycerides) its main...
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...Energy Metabolism of the Canis familiaris Kristy Stewart 17153535 1. Introduction Understanding where, and how the energy that enables life to exist comes from, known as energy metabolism (Cox and Nelson 2013), is integral to understanding health and nutrient needs for organisms. The study of energy metabolism is applicable in many areas; medicine and agricultural livestock health and production are two major applications for this discipline of study. There are different forms of energy metabolism throughout organisms on this planet, however many share the same basic cycles and functions at a metabolic rate. For example, a practically universal central pathway for the metabolism of glucose is glycolysis; the break down of glucose to attain metabolic energy to do biological work (Cox and Nelson 2013). Energy is obtained by harvesting the energy trapped in chemical bonds of food molecules (nutrients). Depending on the nutrient type an organism consumes, the energy metabolism pathways alter slightly. The major constituents of food are carbohydrates, lipids and proteins (Da Poian et al. 2010). This discussion paper will look at the energy metabolism of the Canis familiaris’ (dog) energy metabolism and regulation. 2. Diet, digestion and absorption The dog is a carnivore and consumes a diet consisting mainly of fat and protein with a small amount of carbohydrates (Edwards et al. 2011). The digestive tract of the dog is relatively simple compared to herbivores,...
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...Foods that Speed up Metabolism Are your troubled with a high body fat level? Are you worried with your increased body weight? Different theories have been put up by different people about breaking down fats or losing weight, but it is crucial to have a proper understanding of our nutritional requirement for one to have a vibrant health. It is true that specific kind of food have a direct influence on the rate of metabolic reaction. Therefore, addition of these groups of food in out diet may be a big boost to the whole exercise of cutting down weight. Eating healthy It is undisputable fact that our bodies are made of what we eat. If the choice of food we eat is guided by principles rather popular belief, a great benefit can be witnessed. This is with regards to the health benefits associated with nutrition. Below is a list of some of the best food that the body will greatly benefit from to assist in metabolism. They all have these properties; they have a high water content, high fiber levels with high nutritional value. ➢ Whole grains. The use of whole grains such as oatmeal and brown rice is known to help in weight management. These grains are full of nutrients and rich in complex carbohydrates that accelerate the rate of metabolic reactions. The digestion of these complex carbohydrates takes place at a slower rate compared to the other refined carbohydrates. As a result, the body’s insulin levels are stabilized with no sharp increase in sugar levels. Generally, when...
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...Metabolism III: Oxidative Cellular Respiration Introduction Oxidative cellular respiration is composed of series metabolic processes that convert broken down food molecules into usable energy in the form of adenosine tri-phosphate (ATP). The process follows oxidation (catabolic) and reduction (anabolic) pathways. Processes involved are glycolysis, Krebs or tricarboxylic acid (TCA) cycle, and the electron transport chain. One step in the TCA cycle is the enzyme-catalyzed conversion of succinate to fumarate in a redox reaction. In intact cells succinate loses hydrogen ions and electrons to FAD to form fumarate. This step in the TCA cycle will be used to study the rate of cellular respiration under different conditions. (Patriquin, M. Rand, T. 2012). Since DPIP is a reducing dye it will absorb the hydrogen ions and electrons from the redox reaction of the TCA cycle between succinate and fumarate producing a discoloration of the dye. The discoloration is measured in percent transmittance of light over 30minutes at 5 minute intervals. The change in dye color is the associated with cellular respiration activity, and will be used to record the cellular respiration rate in mitochondria isolated from pulverized lima beans (Phaseolus lunatus) and subsequent effects of different substrate concentration, pH, and metabolic inhibitors . If the difference of light percent transmission produced by (DPIP) can be recorded over time associated with the cellular respiration rate then...
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...and tracheostomy[6]. Additionally, it has been suggested that patients with iron deficiency could also be more susceptible to infections than those with a normal iron status[7–9]. In fact, iron is a fundamental nutrient for humans, but also a key element for bacteria growth[10–13]. Essentially, free iron in circulation promotes the release of siderophores by various bacteria, which in turn, allows the latter to compete with the host for the existing free iron. To enhance bacterial growth, the iron complexes formed are thus incorporated by receptor-mediated endocytosis[14, 15]. Moreover, evidence also suggests that a second mechanism exists for acquiring available iron in the bloodstream, through the secretion of hemolysins[16]. Iron metabolism is extensively altered by inflammation. In fact, sequestration of this element normally occurs in response to an acute inflammatory reaction, which might represent part of a defense mechanism of the human body[10]. For patients admitted to the ICU, two correlations have been established for sepsis: a direct correlation between C-reactive protein (CRP) and ferritin concentrations and an inverse correlation between CRP concentration and transferrin values in the first day of hospitalization[17]. Furthermore, Fernandez et al have demonstrated, in a small sample of ICU patients, that functional iron deficiency measured by reticulocyte hemoglobin content is associated to worst outcomes such as ICU acquired infections and higher length of stay[18...
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...reactions. When these chain reactions occur in cells they can cause damage to the cell’s DNA that in turn causes muscle, joint, and tendon damage and inflammation. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions. Antioxidants such as vitamin C and E can play an important role in reducing inflammation, fatigue, tissue damage, and both prevent and treat injuries. This can play a major role when trying to gain muscle mass due to the fact that your muscles break down when working out. Antioxidants are a vital supplement for athletes as well as body builders. When you exercise heavily in any form, your body actually produces free radicals because your energy systems and metabolism are working at such a high capacity. Taking antioxidant supplements daily can reduce the chances of these free radicals harming your cell production and tissue growth and repair. One of the most important antioxidants that athletes as well as the general public should consume daily is Vitamin C. Your body uses large amounts of vitamin C to fight off infections, colds, and disease and other healing situations such preventing cancer, healing wounds, and reducing damage from free radicals. Most importantly, extra vitamin C improves immune system functions, creates healthy blood vessel functions, and helps keep arterial walls clear from blockage. High levels of vitamin C also suppress your body's release of cortisone. Cortisone is a hormone...
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...Biology – Science 206 Energy, Metabolism, and Cells – Photosynthesis & Cellular Respiration John Carter August 11, 2013 1. Explain how photosynthesis and respiration are linked in order to provide you with energy from the food you eat. Photosynthesis can be defined as the process that living organisms such as plants use to translate the sun’s energy into chemical energy. Once the plant has translated the sun’s energy into chemical energy it then releases that energy and makes it readily available to other living things (Vermaas, 2007). Aerobic respiration can be defined as nutrients being converted into useful energy. Respiration allows cells to use the energy stored during the photosynthesis process. It’s the chemical reaction that breaks down the glucose and changes it into a larger amount of Adenosine Triphosphate which is also called ATP (Board, 2012). Plants use sunlight to make ATP for its energy source by creating a series of chemical reactions by producing oxygen as a waste product. Next, animals and human beings eat these plants. The nutrients digested by animals and human beings reverse the process by using the ATP as a source of energy. Our cells use the nutrients from the plants and convert the nutrients in a process that uses oxygen (Board, 2012). Once our bodies have used all the nutrients will be need from those plants our bodies as well as animals release carbon dioxide as waste. Photosynthesis and respiration are both means of converting...
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