Unreferenced date May 2009 Merge to Endergonic reaction date January 2012 Endergonic from the prefix endo , derived from the Greek word endon , within , and the Greek word ergon , work thermodynamics work means absorbing energy in the form of work. Endergonic reactions are not spontaneous. By thermodynamic standards, positive work, a form of energy , is defined as moving from the wikt surroundings surroundings the external region to the system the internal region . Thus, an endergonic process, as contrasted with an exergonic process, is one wherein the system absorbs energy from the surroundings. As a result, during an endergonic process, energy is put into the system. If the transformation occurs at constant pressure and temperature, G 0 . An endergonic reaction is a chemical reaction that absorbs energy in the form of work. A good example of a net endergonic process is photosynthesis . Also, in metabolism , an endergonic process is anabolic , meaning, that energy is stored. In metabolism, catabolic and anabolic processes are coupled by Adenosine triphosphate ATP . See also col begin col break Exergonic Exergonic reaction Exothermic Endothermic col break Exothermic reaction Endothermic reaction Warm blooded Endotherm Warm blooded Exotherm col end Category Thermodynamics Category Chemical thermodynamics ar hu Endergonikus reakci nl Endergoon ... more details
unreferenced date May 2009 In thermochemistry chemical thermodynamics , an endergonic reaction also called an unfavorable reaction or a nonspontaneous reaction is a chemical reaction in which the standard change in Thermodynamic free energy free energy is positive, and energy is absorbed. In layman s terms the total amount of energy is a loss it takes more energy to start the reaction than what you get out of it so the total energy is a negative net result. For an overall gain in the net result see Exergonic reaction Exergonic Reaction . Under constant temperature and constant pressure conditions, this means that the change in the standard Gibbs free energy would be positive math Delta G circ 0 math for the reaction at standard state i.e. at standard pressure 1 Bar unit bar , and standard concentrations 1 Concentration Molarity molar of all the reagents . Equilibrium constant The equilibrium constant for the reaction is related to G by the relation math K e frac Delta G circ RT math where ... backwards toward equilibrium, not forwards. Nevertheless, endergonic reactions are quite common in nature, especially in biochemistry and physiology . Examples of endergonic reactions in cells include ... conduction and muscle contraction . Making Endergonic reactions happen Endergonic reactions can ... in Free Energy process. Pull Reagents can be pulled through an endergonic reaction, if the reaction ... of the endergonic reaction thus always remains low, so the reaction can proceed. A classic example ... of getting to the top of the activation energy activation energy barrier to the transition state is endergonic ... evolves via an exergonic process to the more stable final products. Push Endergonic reactions can ... longrightarrow XY math may be too endergonic to occur. However it may be possible to make it occur ... to make an endergonic reaction occur, is so common in cell biochemistry that ATP is often called the universal energy currency of all living organisms. See also Endergonic Exergonic Exergonic reaction ... more details
For Exergonic and Endergonic reactions , see the separate articles Endergonic reaction Exergonic reaction See also Exergonic Endergonic Exothermic Endothermic Disambig ... more details
One source date May 2009 Wiktionary exergonic Exergonic from the suffix exo , derived for the Greek word ex , outside and the suffix ergonic, derived from the Greek word ergon , work thermodynamics work means releasing energy in the form of work . In thermodynamics, work is defined as the energy moving from the system the internal region to the surroundings the external region during a given process. An exergonic process is one in which there is a positive flow of energy from the system to the surroundings. This is in contrast with an endergonic process. ref GoldBookRef title exergonic exoergic reaction file E02262 ref Constant pressure, constant temperature reactions are exergonic iff the Gibbs free energy is negative G 0 . All physical and chemical systems in the universe follow the second law of thermodynamics and proceed in a downhill, i.e., exergonic , direction. Thus, left to itself, any physical or chemical system will proceed, according to the second law of thermodynamics , in a direction that tends to lower the thermodynamic free energy free energy of the system, and thus to expend energy in the form of work. These reactions occur spontaneously. See also col begin col break Endergonic Endergonic reaction Exothermic Endothermic Exergonic reaction col break Exothermic reaction Endothermic reaction Warm blooded Endotherm Warm blooded Exotherm col end References Reflist Category Thermodynamics Category Chemical thermodynamics de Exergone und endergone Reaktion fr R action exergonique hu Exergonikus reakci nl Exergoon pt Exerg nica ... more details
An exergonic reaction is a chemical reaction where the change in the Gibbs free energy is negative, ref IUPAC Gold Book definition http www.iupac.org goldbook E02262.pdf search Exergonic 20reaction exergonic exoergic reaction ref indicating a spontaneous reaction . Symbolically, the release of Gibbs free energy, G , in an exergonic reaction is denoted as math Delta G G rm products G rm reactants 0. , math Although exergonic reactions are said to occur spontaneously , this does not imply that the reaction will take place at an observable Reaction rate rate . For instance, the Catalysis Background disproportionation of hydrogen peroxide is very slow in the absence of a suitable catalyst. It has been suggested that eager would be a more intuitive term in this context. ref cite journal doi 10.1021 ed061p710 last Hamori first Eugene coauthors James E. Muldrey year 1984 title Use of the world eager instead of spontaneous for the description of exergonic reactions journal Journal of Chemical Education volume 61 issue 8 pages 710 ref More generally, the terms exergonic and endergonic relate to the Gibbs free energy change in any process, not just chemical reactions. An example of an exergonic reaction is cellular respiration. The terms exothermic and endothermic reactions relate to the enthalpy change of a process. See also Endergonic reaction References reflist Category Thermochemistry de Exergon pl Reakcja egzoenergetyczna ... more details
number endothermic relate to the enthalpy change in any process, not just chemical reactions. In endergonic ... the equilibrium point, and not enthalpy . The related concepts endergonic and exergonic apply ... scanning calorimetry Endergonic Exergonic Endergonic reaction Exergonic reaction Exothermic ... more details
about the physical effect self maintained thermal homeostasis Endotherm In thermodynamics , the word endothermic within heating describes a process or reaction in which the system absorbs energy from the surroundings in the form of heat . It is a modern coinage formed from Greek roots as is often the case with scientific terminology . The prefix endo derives from the Greek word endon meaning within, and the latter part of the word comes from the Greek word root therm meaning hot. Hence it refers to a reaction that needs heat. The opposite of an endothermic process is an exothermic process, one that releases energy in the form of heat. Thus in each term endothermic & exothermic the prefix refers to where heat goes as the reaction occurs. The term endothermic was coined by Marcellin Berthelot 25 October 1827 18 March 1907 . The concept is frequently applied in physical sciences to, for example, chemical reactions , where thermal energy heat is converted to chemical bond energy . Implications for chemical reactions Chemical endothermic reactions need heat to be performed. In a thermochemical reaction that is endothermic, the heat is placed on the reactants side heat is necessary for and absorbed during the reaction . Contrast between thermodynamic and biological terminology Note that because of historical accident, students encounter a source of possible confusion between the terminology of physics and biology. Whereas the thermodynamic terms exothermic and endothermic respectively refer to processes that give out heat energy and processes that absorb heat energy, in biology the sense is effectively inverted. The Metabolism metabolic terms ectotherm ic and endotherm ic respectively refer to organisms that rely largely on external heat to achieve a full working temperature, and to organisms that produce heat from within as a major factor in controlling their bodily temperature. See also Endergonic Exothermic Exergonic Exergonic reaction References reflist Ext ... more details
Hammond s postulate , also referred to as the Hammond Leffler postulate , is a hypothesis , derived from transition state theory , concerning the transition state of organic chemical reaction s, which states that ref cite journal doi 10.1021 ja01607a027 author Hammond, G. S. title A Correlation of Reaction Rates journal J. Am. Chem. Soc. year 1955 volume 77 pages 334 338 br Solomons, T.W. Graham & Fryhle, Craig B. 2004 . Organic Chemistry 8th ed. . John Wiley & Sons, Inc. ISBN 0 471 41799 8. br Loudon, G. Marc. Organic Chemistry 4th ed. 2005. br Yarnell, Amanda. Hammond Postulate 1955 paper used transition state theory to explain structure reactivity relationships. Chemical & Engineering News May 19, 2003 , 81 20 , 42 http pubs.acs.org cen science 8120 8120sci2.html ref If two states, for example, a transition state and an unstable intermediate, occur consecutively during a reaction process and have nearly the same energy content, their interconversion will involve only a small reorganization of the molecular structures. Interpreting the postulate Effectively, the postulate states that the structure of a transition state resembles that of the species nearest to it in Thermodynamic free energy free energy . That is to say that the transition state of an endothermic reaction resembles the products, while that of an exothermic reaction resembles the reactant s. A transition state that resembles the reactants more than the products is said to be early, while a transition state that resembles the products more than the reactants is said to be late. Thus, the postulate predicts an early transition state for an exergonic reaction and a late transition state for an endergonic reaction. A dimensionless reaction coordinate quantifying the lateness of a transition state can be used to test the validity of the postulate for a particular reaction. ref A dimensionless reaction coordinate for quantifying the lateness of transition states Thomas A. Manz, David S. Sholl J. Comput. C ... more details
oxidation reaction drives the endergonic second reaction G 50 kJ mol 12kcal mol , in which a molecule ... to oxidation, and the overall reaction is somewhat endergonic G 6.3 kJ mol 1.5 . Energy coupling ... more details
Distinguish Glycogenesis Glyceroneogenesis Gluconeogenesis abbreviated GNG is a metabolic pathway that results in the generation of glucose from non carbohydrate carbon substrates such as lactic acid lactate , glycerol , and glucogenic amino acid s. 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 . ref cite web last Silva first Pedro title The Chemical Logic Behind Gluconeogenesis url http www2.ufp.pt pedros bq gng.htm accessdate September 8, 2009 ref Gluconeogenesis is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms. ref cite book title Lehninger Principles of Biochemistry year 2000 publisher Worth Publishers location USA isbn 1 57259 153 6 pages 724 author David L Nelson and Michael M Cox ref In vertebrates, gluconeogenesis takes place mainly in the liver and, to a lesser extent, in the cortex of kidney s. This process occurs during periods of fasting , starvation , low carbohydrate diet s, or intense exercise and is highly endergonic . For example, the pathway leading from pyruvate to glucose 6 phosphate requires 4 molecules of ATP and 2 molecules of GTP. 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. ref name Hundal cite journal author Hundal R, Krssak M, Dufour S, Laurent D, Lebon V, Chandramouli V, Inzucchi S, Schumann W, Petersen K, Landau B, Shulman G title Mechanism by Which Metformin Reduces Glucose Production in Type 2 Diabetes journal Diabetes volume 49 issue 12 pages 2063 9 year 2000 pmid 11118008 doi 10.2337 diabetes.49.12.2063 pmc 2995498 PDFlink http diabetes.diabetesjournals.org cgi reprint 49 12 2063 Free full text 82 Kibibyte KiB ref Precursors Fil ... more details
reaction s are energy releasing reactions and are generally catabolic. Endergonic reactions require ... catabolic, exergonic, anabolic, endergonic reactions. Adenosine Triphosphate ATP is the intermediate molecule that drives the exergonic transfer of energy to switch to endergonic anabolic reactions used ... more details
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