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Metabolism Transformations and Interactions Copyright 2005 Wadsworth Group, a division of Thomson Learning Metabolism • Photosynthesis • Fuel • Metabolism Copyright 2005 Wadsworth Group, a division of Thomson Learning Chemical Reactions Copyright 2005 Wadsworth Group, a division of Thomson Learning Adenosine Triphosphate Copyright 2005 Wadsworth Group, a division of Thomson Learning Chemical Reactions • Coupled reactions Copyright 2005 Wadsworth Group, a division of Thomson Learning A Typical Cell Copyright 2005 Wadsworth Group, a division of Thomson Learning Chemical Reactions Copyright 2005 Wadsworth Group, a division of Thomson Learning Copyright 2005 Wadsworth Group, a division of Thomson Learning Chemical Reactions • Helpers in reactions –Enzymes •Cofactors –Coenzymes Copyright 2005 Wadsworth Group, a division of Thomson Learning Nutrients for Energy Copyright 2005 Wadsworth Group, a division of Thomson Learning Nutrients for Energy • Glycolysis • Pyruvate acetyl CoA • TCA cycle • Electron transport chain Copyright 2005 Wadsworth Group, a division of Thomson Learning Glycolysis: Glucose-toPyruvate Copyright 2005 Wadsworth Group, a division of Thomson Learning Glucose • The fate of pyruvate –Anaerobic vs. aerobic pathways Copyright 2005 Wadsworth Group, a division of Thomson Learning Glucose • The fate of pyruvate –Anaerobic •Pyruvate-to-lactic acid –Cori cycle Copyright 2005 Wadsworth Group, a division of Thomson Learning Pyruvate-to-Lactic Acid (Anaerobic) Copyright 2005 Wadsworth Group, a division of Thomson Learning Glucose • The fate of pyruvate –Aerobic •Pyruvate-to-acetyl CoA Copyright 2005 Wadsworth Group, a division of Thomson Learning Copyright 2005 Wadsworth Group, a division of Thomson Learning Pyruvateto-Acetyl CoA (Aerobic) The Paths of Pyruvate and Acetyl CoA Copyright 2005 Wadsworth Group, a division of Thomson Learning Glucose yields energy Copyright 2005 Wadsworth Group, a division of Thomson Learning Glycerol & Fatty Acids • Glycerol-to-pyruvate Copyright 2005 Wadsworth Group, a division of Thomson Learning Glycerol & Fatty Acids • Fatty acids-to-acetyl CoA Copyright 2005 Wadsworth Group, a division of Thomson Learning Fatty acids-to-acetyl CoA, cont’d This repeating step is also known as beta-oxidation! Fats Enter the Energy Pathway Glycerol & Fatty Acids • Fatty acids cannot be used to synthesize glucose: Why is this important?? Amino Acids • Amino acids-to-acetyl CoA Amino Acids • Amino acids-to-glucose Amino Acids • Deamination – Keto acid – Ammonia Amino Acids • Transamination Amino Acids • • Ammoniato-urea Copyright 2005 Wadsworth Group, a division of Thomson Learning Urea excretion via the kidneys Copyright 2005 Wadsworth Group, a division of Thomson Learning Copyright 2005 Wadsworth Group, a division of Thomson Learning The Final Steps • The TCA cycle – Acetyl-CoA goes in and oxaloacetate comes out...which ironically is used to continue the cycle...? – Many B vitmins used as cofactors. – By-products go into the E- transport chain. –ATP generated along the way! Copyright 2005 Wadsworth Group, a division of Thomson Learning Copyright 2005 Wadsworth Group, a division of Thomson Learning The TCA Cycle The Final Steps • The electron transport chain - Consumes oxygen - Produces carbon dioxide and water - Produces energy as ATP! Copyright 2005 Wadsworth Group, a division of Thomson Learning Electron Transport Chain and ATP Synthesis Copyright 2005 Wadsworth Group, a division of Thomson Learning The Final Steps • The kcalories-per-gram secret revealed Copyright 2005 Wadsworth Group, a division of Thomson Learning The Central Pathways of Energy Metabolism Energy Balance • Feasting—Excess Energy – Excess protein is converted to fat but this is inefficient and indirect. Its priority is other roles. – Excess carbohydrate is converted to fat but this is inefficient and indirect. Its priority is glycogen stores. – Excess fat is efficiently converted to fat. • The transition from feasting to fasting draws on reserves. Economics of Feasting Economics of Fasting Economics of Fasting • Glucose needed for the brain • Protein meets glucose needs • Suppression of appetite • Slowing of metabolism • Are you starving now?? Energy Balance • Fasting—Inadequate Energy – Symptoms of Starvation • Muscle wasting • Decreased heart rate, respiratory rate, metabolic rate, and body temperature • Impaired vision • Organ failure • Decreased immunity • Depression, anxiety, and food-related dreams...yes, if I was starving I would naturally dream about food!
