Hun1201 Study Guide Test 3 Ch 7-9, 14Ch. 7 Why is Metabolism Essential For Life?Metabolism: sum of all chemical and physical changes that occur in body tissuesCalorimeter: instrument in which food can be burned and the amount of heat that is released can be measured; measures energy content of foodThe process of making larger, chemically complex molecules from smaller, more basic ones is called anabolism.Process is critical for growth, repairing and maintaining the body’s tissues, and synthesizing the chemical products essential for human functioningEnergy that fuels anabolic reactions is chemical energyCatabolism: breakdown or degradation or larger, more complex molecules to smaller, basic molecules; releases chemical energyBegins with digestion; macro nutrients are broken down into amino acids, fatty acids, glycerol, and monosaccharide’s and transported to body cells and when cells need energy they can catabolize into smaller moleculesUsed to break down old cells or tissues that need to be repaired or replacedEnergy to fuel anabolic reactions comes from body’s catabolic reactionsBody balances the two reactions; exceptions occur when there is an excess anabolic state during childhood growthWhen cells catabolize nutrients such as glucose, they package the energy that is released during the reaction in a compound called adenosine triphosphate (ATP)When these bonds are broken , their energy is released and can be used to perform the work of the cellEnergy is used to build new molecules, break down old molecules, and keep the cell functioning optimallyAdenosine diphosphate (ADP): a metabolic intermediate that results from the removal of one phosphate groupAdenosine monophosphate (AMP): low energy compound resulting from removal of two phosphate groupsMetabolic pathways are clusters of chemical reactions that occur sequentially and achieve a particular goalCondensation is an anabolic process where smaller compounds are joined by the removal of waterA-OH + H-B A-B + H2OHydrolysis is a catabolic process where large molecules are broken apart by the addition of waterA-B + H2O A-OH + H-BPhosphoralation is the addition of one or more phosphate groups to a chemical compoundExample of when glucose enters a cellC6H12O6 + A-P-P-P C6H12O6-P + A-P-POxidation-reduction reactions are reactions in which electrons are lost by one compound (oxidation) and simultaneously gained by another compound (reduction)Enzymes are essential for the metabolism of the energy-containing macronutrientIn order to function they require substances called coenzyme and cofactorCoenzymes are the smaller, non-protein part of an enzymeFAD, FADH2, and vitamins are coenzymesCofactors are typically minerals, such as iron, magnesium, or zinc, that are required for enzyme activityThe enzyme that activates the metabolic reaction in the phosphorylation of glucose is called glucokinaseThe glucose absorbed from carbohydrates has one of many fatesGlucose can be phosphorylated and stored in liver and glycogen or used for energyGlucose can be released and used up by other cells as fuel or stored in muscle tissue as glycogenOr if energy needs are met then they can converted to fatty acids and stored as adipose tissueEnergy extracted from CarbohydratesGlycolysis is a sequence of chemical reactions that converts glucose to pyruvateoccurs in the cytosolanaerobicrequires 2 ATPs, but produces 4 ATPs= 2 net ATPs to be used as energy2 Hs that are released are picked up by the coenzyme NAD, thus forming NADHPyruvate molecules can be used up as energy after undergoing metabolic steps, or can be resynthesized to glucose through gluconeogenesisIn the absence of oxygen, the pyruvate produced in gylcolysis can be anaerobically converted to lactate (or lactic acid)Occurs in a one step reaction where H is acquiredLactate is produced from the NADH + H yielded during gylcolysis; so the production of lactate therefore regenerates the NAD required for the continued function of the gylcolysis pathwayOccurs in cells with few or no mitochondria, and in muscles during high intensity exercise when oxygen delivery to the muscles is limitedIn the presence of oxygen, pyruvate is converted to a two carbon compound known as Acetyl CoA and occurs in the mitochondria.Reactions takes in NAD and produces NADH + HAcetyl CoA is a two carbon compound, where the third C from pyruvate end up with the gas CO2 which the lung exhalesAcetyl CoA cant be resynthesized to glucose like lactate can, but can be metabolized to produce ATP, or redirected into fatty acid synthesis when ATP is abundantThe tricarboxylic acid (TCA) cycle (creb cycle) is a repetitive series of 8 metabolic reactions, located in cell mitochondria, that metabolizes acetyl CoA for the production of carbon dioxide, high-energy GTP, and reduced coenzymes NADH and FADH2Oxaloacetate and other metabolic intermediates are necessary for continued functioning of the TCA cycle. Oxaloacetate is mostly derived from dietary carbohydratesEvery glucose after gylcolysis produces 2 pyruvate’s, leading to two acetyl CoA’s. So 1 glucose molecule =2 TCA cyclesFinal stage in glucose oxidation is called oxidative phosphorylationOccurs in the electron transport chain, a series of metabolic reactions that transports electrons from NADH or FADH2 through a series of carriers, resulting in ATP productionThe complete process of glucose oxidation starts with glucose and ends with the production of carbon dioxide, water, and ATPEnergy extracted from FatsLipolysis is the enzyme-driven catabolism of triglycerides into free fatty acids (3) and glycerolTriglycerides are broken down though the enzyme lipoprotein lipase in lipoproteins , and by hormone-sensitive lipase in adipose cellsThe glycerol part of the triglyceride doesn’t produce much energy but can be converted to pyruvate, or used for regeneration of glucoseThe fatty acids are attached to albumin, a blood protein, and transported to cells that need energyThey are catabolized for energy through the process -oxidation (fatty acid oxidation)The fatty acid must first be activated by Coenzyme A before its shuttled across the mitochondrial membrane by carnitineMore acetyl CoA and more ATP are produced during -oxidation than during glucose catabolismFatty acids have a higher energy potential (9 kcal/g) compared to carbohydrates (4 kcal/g)There is no metabolic pathway that converts fatty acids to glucoseIf there is a low intake of carbohydrates then the TCA
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