ch25ppt - 25-1Chapter 25Metabolism•Functions of food...

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Unformatted text preview: 25-1Chapter 25Metabolism•Functions of food –source of energy–essential nutrients –stored for future use•Metabolism is all the chemical reactions of the body–some reactions produce the energy stored in ATP that other reactions consume–all molecules will eventually be broken down and recycled or excreted from the body25-2Catabolism and Anabolism•Catabolic reactions breakdown complex organic compounds–providing energy (exergonic)–glycolysis, Krebs cycle and electron transport•Anabolic reactions synthesize complex molecules from small molecules –requiring energy (endergonic)•Exchange of energy requires use of ATP (adenosine triphosphate) molecule.25-3ATP Molecule & Energy•Each cell has about 1 billion ATP molecules that last for less than one minute•Over half of the energy released from ATP is converted to heat25-4Energy Transfer•Energy is found in the bondsbetween atoms•Oxidation is a decrease in the energy content of a molecule•Reduction is the increase in the energy content of a molecule •Oxidation-reduction reactions are always coupled within the body–whenever a substance is oxidized, another is almost simultaneously reduced.25-5Oxidation and Reduction•Biological oxidation involves the loss of (electrons) hydrogen atoms –dehydrogenation reactions require coenzymes to transfer hydrogen atoms to another compound–common coenzymes of living cells that carry H+•NAD (nicotinamide adenine dinucleotide )•NADP (nicotinamide adenine dinucleotide phosphate ) •FAD (flavin adenine dinucleotide )•Biological reduction is the addition of electrons (hydrogen atoms) to a molecule–increase in potential energy of the molecule25-6Mechanisms of ATP Generation•Phosphorylation is –bond attaching 3rd phosphate group contains stored energy •Mechanisms of phosphorylation –within animals•substrate-level phosphorylation in cytosol•oxidative phosphorylation in mitochondria–in chlorophyll-containing plants or bacteria•photophosphorylation.25-7Phosphorylation in Animal Cells•In cytoplasm (1)•In mitochondria (2, 3 & 4) 25-8Carbohydrate Metabolism--In Review•In GI tract–polysaccharides broken down into simple sugars –absorption of simple sugars (glucose, fructose & galactose)•In liver –fructose & galactose transformed into glucose–storage of glycogen (also in muscle)•In body cells --functions of glucose–oxidized to produce energy–conversion into something else–storage energy as triglyceride in fat 25-9Fate of Glucose•ATP production during cell respiration–uses glucose preferentially •Converted to one of several amino acids in many different cells throughout the body •Glycogenesis–hundreds of glucose molecules combined to form glycogen for storage in liver & skeletal muscles•Lipogenesis (triglyceride synthesis)–converted to glycerol & fatty acids within liver & sent to fat cells25-10Glucose Movement into Cells•In GI tract and kidney tubules, Na+/glucose symporters•Most other cells, GluT facilitated...
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This note was uploaded on 04/10/2010 for the course BIO 222 taught by Professor Brooks during the Spring '10 term at Prairie State College .

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ch25ppt - 25-1Chapter 25Metabolism•Functions of food...

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