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• Metabolism


  Sum total of all the biochemical reactions that take place in a living organism
• Catabolism


  Large biochemical molecules are broken down to smaller ones (release energy)
• Anabolism


  Small biochemical molecules are joined together to form larger ones (require energy)
• Metabolic Pathway


  1. Series of consecutive biochemical reactions used to convert a starting material into an end product

  2. Linear metabolic pathway - generates a final product

  3. Cyclic metabolic pathway - regenerates the first reactant
• Prokaryotic cells


  No nucleus and are found only in bacteria
• Eukaryotic cells


  DNA is found in a membrane-enclosed nucleus
• Cytoplasm


  Water-based material of a eukaryotic cell; lies between nucleus and outer membrane
• Organelle


  Minute structure within the cytoplasm; carries out specific cellular function; surrounded by cytosol
• Cytosol


  Water-based fluid part of the cytoplasm
• Three Important Organelles


  • Ribosomes - Site of protein synthesis
  • Lysosomes - Contains hydrolytic enzymes needed for cellular rebuilding, repair, and degradation
  • Mitochondria - Responsible for the generation of most of the energy for a cell
• Mitochondria


  • Sausage-shaped, containing both an outer membrane and multifolded inner membrane
  • Outer membrane - 50% lipid, 50% protein, freely permeable
  • Inner membrane - 20% lipid, 80% protein, highly impermeable
  • Matrix - interior region
  • Intermembrane space - region between inner and outer membranes
  • Cristae - folds of the inner membrane that protrude into the matrix
• Adenosine Phosphates


  • ATP - Adenosine triphosphate
  • ADP - Adenosine diphosphate
  • AMP - Adenosine monophosphate
• Flavin Adenine Dinucleotide (FAD, FADH2)


  A coenzyme required in numerous metabolic redox reactions
• Nicotinamide Adenine Dinucleotide (NAD+, NADH)


  A coenzyme required in numerous metabolic redox reactions
• Coenzyme A (CoA – SH)


  Derivative of B vitamin pantothenic acid
• Acetyl group


  Portion of an acetic acid molecule (CH3 – COOH) that remains after the –OH group is removed from the carboxyl carbon atom
• Acetyl group + CoA–SH → acetyl CoA
• Simple Carboxylic Acids


  • Succinic acid - 4-Carbon diacid
  • Glutaric acid - 5-Carbon diacid
• High-energy compound


  A compound that has a greater free energy of hydrolysis than that of a typical compound; differ from other compounds in that they contain one or more very reactive bonds (strained bonds)
• Stage 1: Digestion


  Begins in the mouth, continues in the stomach, and is completed in the small intestine
• Stage 2: Acetyl group formation


  Primary products include two-carbon acetyl units (which become attached to coenzyme A to give acetyl CoA) and the reduced coenzyme NADH
• Stage 3: Citric Acid Cycle

  Occurs inside mitochondria; acetyl groups are oxidized to produce CO, and energy. Some of the energy released by these reactions is lost as heat, and some is carried by the reduced coenzymes NADH and FADH, to the fourth stage
• Stage 4: Electron Transport Chain and Oxidative Phosphorylation


  Occurs inside mitochondria. NADH and FADH, supply the "fuel" (hydrogen ions and electrons) needed for the production of ATP molecules, the primary energy carriers in metabolic pathways. Molecular O2, inhaled via breathing, is converted to H2O in this stage
• The Citric Acid Cycle


  1. Step 1. Condensation

  2. Step 2. Isomerization

  3. Step 3. Oxidation and decarboxylation

  4. Step 4. Oxidation and decarboxylation

  5. Step 5. Phosphorylation

  6. Step 6. Oxidation

  7. Step 7. Hydration

  8. Step 8. Oxidation
• The Electron Transport Chain


  1. NADH and FADH2 produced in the citric acid cycle pass the electron transport chain

  2. Electron Transport Chain - Series of biochemical reactions in which electrons and hydrogen ions from NADH and FADH2 are passed to intermediate carriers and then ultimately react with molecular oxygen to produce water

  3. Complex I: NADH – Coenzyme Q Reductase

  4. Complex II: Succinate – Coenzyme Q Reductase

  5. Complex III: Coenzyme Q – Cytochrome Reductase

  6. Complex IV: Cytochrome c Oxidase
• Cytochrome


  Heme containing protein in which reversible oxidation and reduction of an iron atom occur
• Oxidative Phosphorylation


  Biochemical process by which ATP is synthesized from ADP as a result of the transfer of electron and hydrogen ions from NADH or FAHD2 to O2 through the electron carriers involved in the electron transport chain
• Coupled reactions


  Pairs of biochemical reactions that occur concurrently in which energy released by one reaction is used in the other reaction
• Chemiosmotic Coupling


  1. The "proton flow" of ATP-ETC coupling. An explanation for the coupling of ATP synthesis with electron transport chain reactions

  2. The result of pumping of protons in the mitochondrial matrix across the inner mitochondrial membrane is a higher concentration of protons in the intermembrane membrane space than in the matrix. This concentration difference constitutes an electrochemical (proton) gradient.

  3. A spontaneous flow of proton from the region of high concentration to low occurs because of the gradient.

  4. ATP synthase has 2 subunits F° and F¹. The F° part of the synthase is the channel for proton flow, whereas the formation of ATP occurs in F¹ subunit.

  5. The ATP produced through oxidative phosphorylation must be moved from the matrix back to the intermembrane space before it can be used for metabolic reactions.
• 3 NADH → 7.5 ATP

  1 FADH2 → 1.5 ATP

  1 GTP → 1 ATP
• Total ATP production: 10 ATP
• Highly Reactive Oxygen Species (ROS)

  Hydrogen peroxide (H2O2)

  Superoxide ion (O2‾)

  Hydroxyl radical (OH)
• Phytochemical


  Nonnutrient compound found in plant-derivative foods that has a positive effect on human health
• Four Vitamins Involved in Metabolic Reactions

  • Niacin - NAD+ and NADH

  Riboflavin - FAD, FADH2, and FMN

  Thiamin - TPP

  Pantothenic acid - CoA