Midterms 7

• ATP


  The primary energy carrier in metabolic pathways
• Metabolism


  The total biochemical reactions occurring in a living organism
• Types of metabolism

  • Catabolism - the destructive portion, breakdown of larger molecules to simpler ones
  • Anabolism - the constructive portion, synthesis of complex molecules from simpler ones
• Catabolism


  The breakdown of larger molecules to simpler ones (e.g. starch to monosaccharides)
• Anabolism


  The synthesis of complex molecules from simpler ones (e.g. glucose to glycogen)
• Biochemical energy production process

  1. Stage 1: Digestion

  2. Stage 2: Acetyl group formation

  3. Stage 3: Citric Acid Cycle

  4. Stage 4: Electron transport chain and oxidative phosphorylation
• Digestion


  • Begins in mouth, continues in stomach, completed in small intestine
  • Results in small molecules that can cross intestinal membrane into the blood
• End products of digestion


  • Glucose and monosaccharides from carbohydrates
  • Amino acids from proteins
  • Fatty acids and glycerol from fats and oils
• Acetyl group formation


  1. Small molecules from Stage 1 are further oxidized

  2. End product is acetyl CoA
• Acetyl CoA


  The end product of the oxidation reactions
• NAD


  Coenzyme that is reduced to NADH during oxidation reactions
• NADH


  The reduced form of NAD, indicates the presence of hydrogen
• Citric Acid Cycle

  1. Takes place inside the mitochondria

  2. Acetyl group is oxidized to produce CO2 and energy

  3. Most energy is trapped in reduced coenzymes NADH and FADH2

  4. Some energy is lost as heat
• Citric Acid Cycle

  Also known as the Tricarboxylic Acid (TCA) Cycle or Krebs Cycle
• Citric Acid Cycle

  • Oxidation of NAD+ and FAD to produce NADH and FADH2
  • Decarboxylation of citric acid to produce carbon dioxide
• Electron Transport Chain and Oxidative Phosphorylation

  1. NADH and FADH2 are oxidized to release H+ and electrons

  2. H+ are transported to the inter-membrane space in mitochondria

  3. Electrons are transferred to O2 and O2 is reduced to H2O

  4. H+ ions reenter the mitochondrial matrix and drive ATP-synthase reaction to produce ATP
• Electron Transport Chain


  A series of biochemical reactions in which electrons are transferred from NADH and FADH2 to oxygen, which is reduced to water
• Protein complexes in the Electron Transport Chain

  • Complex 1: NADH-coenzyme Q reductase
  • Complex 2: Succinate-coenzyme Q reductase
  • Complex 3: Coenzyme Q - cytochrome C reductase
  • Complex 4: Cytochrome C oxidase
• Cytochrome


  A heme iron protein in which reversible oxidation of an iron atom occurs, acting as an electron carrier
• Oxygen gas serves as the major and final acceptor of electrons in the Electron Transport Chain