Metabolism_11th_ed.pdf

Anatomy & Physiology I BIOL 2001 C Ibanez Metabolism pp. 940-957 1. Metabolism: totality of an organism’s reactions a. Catabolism: breakdown b. An...

Anatomy & Physiology I BIOL 2001 C Ibanez Metabolism pp. 940-957 1. Metabolism: totality of an organism’s reactions a. Catabolism: breakdown b. Anabolism: synthesis 2. Growth Requirements a. COHN b. Trace elements c. Vitamins d. Sugars e. Amino Acids i. Essential – must be consumed in the diet ii. Nonessential 3. Energy Requirements a. Energy currency within cells → ATP (adenosine triphosphate) b. Most energy originates from photosynthesis 4. Laws of Thermodynamics a. First Law (Law of Conservation of Energy) i. Energy cannot be created, nor destroyed, only transformed from one form to another b. Second Law (Entropy) i. The universe will tend toward disorder. c. Third Law (Absolute Zero) i. At absolute zero, the entropy of a perfect crystal is equal to zero 5. Enthalpy of Reaction a. Endothermic: (+ΔH) Absorption of heat; energy is added to the system b. Exothermic: (-ΔH) Evolves heat; energy is removed from a system 6. Enzymology a. Enzymes (-ase): protein catalysts i. Lower the activation energy of reactions ii. Regulate metabolic pathways iii. Increase the rate of reaction by 108 to 1011 times iv. Can be synthesized in an active or inactive form Anatomy & Physiology I BIOL 2001 C Ibanez b. Types of Enzymes: i. Oxidoreductase: change the state of oxidation ii. Transferase: transfer functional groups iii. Hydrolase: split molecules by adding water iv. Lyase: split molecule without adding water v. Isomerase: rearrange molecules vi. Ligase: join molecules vii. Protease: catabolize proteins c. Enzyme Components: i. Apoenzyme: protein portion ii. Cofactor: trace elements e.g. Mg++, Ca++, etc. iii. Coenzyme: vitamin iv. Holoenzyme: Apoenzyme + Cofactor/Coenzyme d. Enzyme Action: i. Enzyme + Substrate(s) → Enzyme-Substrate Complex → Enzyme + Product(s) ii. A mutation at the active site results in the loss of activity iii. Mutations at other sites have the potential to alter the enzymatic activity Anatomy & Physiology I BIOL 2001 C Ibanez e. Metabolic Control: i. pH i. Changes charges on the enzyme, which will change the protein structure ii. Temperature i. Too high → Denaturation a. Reversible b. Nonreversible ii. Too low → Low enzyme activity iii. Enzyme concentration is directly proportional to product formation if the substrate is in excess iv. Substrate concentration is directly proportional to product formation if the enzyme is in excess v. Product Concentration i. Negative Feedback: mechanism in which a product acts to decrease the production of itself ii. Positive Feedback: mechanism in which a product acts to increase the production of itself iii. Equilibrium → Death vi. Inhibitors: i. Competitive: compete for the active site a. Reversible b. Nonreversible ii. Non-competitive: bind at a site other than the active site to alter the configuration of the enzyme Anatomy & Physiology I BIOL 2001 C Ibanez 7. Metabolism of Carbohydrates a. Polysaccharides are hydrolyzed to disaccharides and then to monosaccharides b. Monosaccharides are then converted to glucose (generally) c. Glycolysis i. Occurs in the cytoplasm d. Fermentation (if oxygen is not present) i. Lactic Acid Fermentation ii. Alcohol Fermentation e. Cellular Respiration (if oxygen is present) i. Pyruvate Oxidation i. Occurs on the mitochondrial outer membrane ii. Krebs Cycle/Citric Acid Cycle i. Occurs within the mitochondria iii. Electron Transport Chain i. Occurs on the mitochondrial inner membrane f. Summary g. Lactic Acid Fermentation Glucose → 2 Lactic Acid + 2 ATP h. Alcohol Fermentation Glucose → 2 Ethanol + 2 CO2 + 2 ATP i. Cellular Respiration Glucose + 6 O2 → 6 CO2 + 6 H2O + Energy i. In eukaryotes, 36 ATP ii. In prokaryotes, 38 ATP 8. Protein Catabolism a. Hydrolysis to form individual amino acids b. Deamination: removal of the amino group c. Enters pathways similar to glucose metabolism 9. Lipid Catabolism a. Hydrolysis to break into glycerol and three fatty acid chains b. Fatty acids are broken down into 2 carbon molecules c. These smaller molecules then can enter pathways similar to glucose metabolism