Respiration

• Mitochondria


  A site of aerobic respiration in the cell
• Respiration


  1. Glucose is broken down in the cytoplasm

  2. Substrate is transported into the mitochondria

  3. Further processing to release ATP
• Mitochondria


  • Double membrane structure
  • Outer membrane for compartmentalization
  • Inner membrane with cristae to increase surface area
  • Contains proteins for electron transport chain and ATP synthase
  • Inter-membrane space for proton concentration gradient
  • Matrix contains enzymes for link reaction and Krebs cycle, and mitochondrial DNA
• Mitochondria used to be a bacteria that was absorbed by cells and evolved into a symbiotic relationship
• Mitochondrial DNA is an exact copy from the mother, which is used to trace the origin of mitochondrial Eve
• Mitochondrial Eve is the single lady from Africa that all human mitochondrial DNA can be traced back to
• Glycolysis


  1. Glucose gets two phosphate groups donated from two ATP's to become hexose bisphosphate

  2. Hexose bisphosphate splits up into two triose phosphate

  3. Triose bisphosphate is converted into pyruvate with two ADP collecting the phosphate groups to become two ATP

  4. NAD comes along and steals a hydrogen atom from triose bisphosphate, becoming reduced
• Glycolysis


  The first stage of aerobic respiration, happening in the cytoplasm, involving the breakdown of glucose
• Hexose bisphosphate


  Glucose with two phosphate groups added
• Triose phosphate


  The two halves of the split hexose bisphosphate
• Triose bisphosphate


  Triose phosphate with an additional phosphate group added
• Pyruvate


  The final product of glycolysis, missing two phosphate groups
• NAD


  A coenzyme that comes along and steals a hydrogen atom from triose bisphosphate, becoming reduced
• Glycolysis


  Produces two pyruvate molecules and a net gain of two ATP
• Reduced NAD


  Can make three ATP molecules in the next stage of respiration
• Glycolysis does not require oxygen or light, unlike photophosphorylation and oxidative phosphorylation which use the electron transport chain and ATP synthase
• The reaction where ADP collects phosphate groups from triose bisphosphate to form ATP is called substrate-level phosphorylation
• Link reaction


  1. Pyruvate to acetyl coenzyme A

  2. Decarboxylation

  3. Oxidative decarboxylation
• Acetyl coenzyme A


  Two carbon molecule formed from pyruvate
• Krebs cycle


  1. Acetyl coenzyme A combines with oxaloacetate to form citrate

  2. Citrate undergoes multiple steps to regenerate oxaloacetate

  3. Generates carbon dioxide, reduced NAD, reduced FAD
• From one pyruvate molecule


  Generates 4 reduced NAD, 1 reduced FAD, 3 carbon dioxide, 1 ATP
• Reduced NAD and reduced FAD feed into the final stage of oxidative phosphorylation
• Decarboxylation


  Removal or loss of a carboxyl group (usually carbon dioxide)
• Oxidation


  NAD becoming reduced
• Substrate level phosphorylation


  ATP made from an unstable intermediate, without the use of electron transport chain or ATP synthase
• Oxidative phosphorylation


  The final stage of aerobic respiration
• Oxidative phosphorylation


  1. Reduced coenzymes release protons and electrons

  2. Electrons enter electron transport chain

  3. Electron transport chain releases energy to pump protons across membrane

  4. Proton concentration gradient forms

  5. Protons diffuse through ATP synthase

  6. ATP synthase uses proton motive force to produce ATP

  7. Oxygen accepts protons and electrons to form water
• Electron transport chain


  • Series of electron carriers that transport electrons
• Proton concentration gradient


  Increased concentration of protons in the intermembrane space compared to the matrix
• Chemiosmosis


  The diffusion of protons down their concentration gradient through ATP synthase to drive ATP production
• Proton motive force


  The energy released as protons diffuse through ATP synthase, which drives ATP production
• Reduced coenzymes


  NADH and FADH2 that carry high-energy electrons and protons from earlier stages of respiration
• Oxygen is the terminal electron acceptor in oxidative phosphorylation, combining with protons and electrons to form water
• Oxidative phosphorylation is the most important stage of respiration for producing ATP
• Aerobic respiration


  Happens mainly in the mitochondria
• Anaerobic respiration


  The body's final survival mechanism when there is not enough oxygen, providing just enough ATP for basic functions
• Types of anaerobic respiration

  • Lactic fermentation in animals
  • Alcoholic fermentation in plants
• Fermentation


  Another name for anaerobic respiration, the breaking down of complex molecules to simpler molecules without the use of oxygen or electron transfer chain
• Lactic fermentation


  1. Glycolysis in cytoplasm

  2. Pyruvate converted to lactate using reduced NAD

  3. Lactate enters bloodstream

  4. Transported to liver

  5. Reacts with oxygen to regenerate glucose (Cori cycle)
• Lactic fermentation


  • Produces lactic acid, which can denature enzymes and proteins causing muscle fatigue
  • Cori cycle uses 6 ATP to regenerate glucose, resulting in a net loss of 4 ATP