Metabolic 2

• Objective of glucose catabolism is to transfer energy from the nutrient molecule to ATP
• Glucose catabolism equation:

  glucose + 6oxygen = 6 carbon dioxide + 6 water + 30 ATP
• 4 steps of cellular respiration:

  1. glycolysis
  2. pyruvate oxidation
  3. citric acid cycle (krebs)
  4. electron transport chain and oxidative phosphorylation
• Location of cellular respiration

  • cytoplasm: glycolysis
  • mitochondria: pyruvate oxidation, krebs cycle, ETC
• Mitochondria:

  • oval sausage shaped organelle
  • found in plants and animal cells
  • power plant of the cell by converting food energy (glucose) into cell energy (ATP)
• Glycolysis

  • happens in cytoplasm
  • anaerobic process (no oxygen)
  • starting molecule is glucose
• Molecules produced in glycolysis

  • 2 ATP net
  • 2 NADH
  • 2 pyruvate molecules (pyruvic acid)
• Pyruvate oxidation

  • happens in the mitochondria
  • aerobic subprocess
  • starting molecule: 2 pyruvate molecules
• Molecules produced in pyruvate oxidation

  • 2 carbon dioxide
  • 2 NADH
  • 2 acetyl CoA molecules
• Krebs cycle

  • happens in the mitochondria
  • aerobic subprocess
  • starting molecule: 2 acetyl CoA molecules that enter the Krebs cycle one at a time
• Total molecules produced in Krebs cycle

  • 2 ATP
  • 2 FADH2
  • 6 NADH
  • 4 carbon dioxide
• Electron transport chain

  • happens in the mitochondria
  • aerobic subprocess
  • NADH and FADH2 molecules take their electrons to the ETC
  • the inner membrane proteins pump hydrogen creating a hydrogen gradient
• Oxidative phosphorylation

  • happens inside the mitochondria
  • aerobic subprocess
  • hydrogen ions move down the concentration gradient through the enzyme ATP synthase
  • ATP synthase drives the production of ATP
• Oxygen present in carbohydrate metabolism

  • aerobic respiration pathway
  • O2 is the last electron acceptor
  • allows transport of electrons down the ETC
  • allows for the formation of large amounts of ATP
• Oxygen absent in carbohydrate metabolism

  • anaerobic respiration pathway = no O2
  • no movement of electrons down ETC
  • not a lot of ATP formation
• Anaerobic pathway: Glucose catabolism is possible through an anaerobic pathway when transfering energy to ATP using only glycolysis. This occurs when there is a lack of oxygen in the skeletal muscle cells during strenuous exercise
• Products of the anaerobic pathway

  • lactic acid is produced but cannot enter the Krebs cycle
  • most of the lactic acid is carried into the liver and is converted to pyruvic acid and then to glucose or glycogen
  • glucose is then stored or returned to the bloodstream for use by other cells (cori cycle)