Cellular Respiration

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Cellular Respiration

• Releasing stored energy from our food

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Cellular Respiration

• The breakdown of food to release stored chemical
  energy and thus make ATP for use in the cell

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Formulas to know and love

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Where? When? Who?

• mitochondria of eukaryotic cells
• As long as food is available and NRG is needed
• ALL living things

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Cellular Respiration

• Follows these 3 steps
• Glycolysis
• Krebs cycle
• Electron Transport Chain
• 2 pathways
• Aerobic
• anaerobic

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1st step for ALL

• Glycolysis
• Occurs in cytoplasm
• Break the cookie
• Glucose is phosphorylated
• PhosphoGlycerALdehyde (PGAL) made
• PGAL changed to 2 pyruvic acid (pyruvate)

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Glycolysis contd

• Uses 2 ATP of NRG, makes 4 ATP for a net gain of
  2 ATP
• Protons (and e-) harvested passed to coenzyme
  carrier - NAD becomes NADH
• Happens with or without oxygen ALL THE TIME

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Oxygen availability determines next step

• NO O
• Anaerobic respiration or Fermentation

• Oxygen available
• Oxidative metabolism
• Krebs cycle/citric acid cycle
• ETC (electron transport chain)

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Anaerobic Fermentation

• When oxygen is low or unavailable
• Occurs in cytoplasm
• NO NRG made protons dumped
• Regenerates NAD needed for glycolysis
• Byproducts depend on organism
• Alcohol, propionic acid, lactic acid

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Aerobic Respiration

• Two steps
• Krebs cycle
• The complete breakdown of glucose
• Harvesting of H and e- (potential energy)
• Makes a little bit of ATP
• Electron Transport Chain
• Where most ATP is made in chemiosmosis

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Krebs Cycle

• Mitochondrial matrix
• Pyruvate from glycolysis is further ripped apart
  release of CO2
• Acetyl-CoA (2C compound) formed to enter Krebs
  cycle
• Hooks up with a 4C sugar (oxaloacetate) to make a
  6C sugar

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• 6-C sugar is ripped apart and rearranged in order
  to harvest protons (H) and electrons (e-)
• NAD and FAD wagons pick up the H/e-
• Oxaloacetate is regenerated for cycle
• Glucose is completely broken down

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ETC Electron Transport Chain

• Occurs on cristae of mitochondria
• Passing of H/e- sets up concentration gradient
  of protons
• Proton pump makes ATP (chemiosmosis or oxidative
  phosphorylation)
• MOST energy of respiration is made here (34-36
  ATP)

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How to clean up all those crumbs of H?

• Oxygen is the janitor
• Final electron/H acceptor
• Makes water from our food crumbs
• ½O2 H H2O

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Comparison of respiration

• Anaerobic
• No O
• Starts with glycolysis
• Only makes 2 ATP
• Waste products of lactic acid, alcohol or
  propionic acid CO2

• Aerobic
• Oxygen available
• Starts with glycolysis
• 2 further steps
• Generates 34-36 ATP
• CO2 is waste product