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Cellular Respiration: Fermentation Ch. 9

Cellular Respiration: Fermentation Ch. 9. Ms. Springstroh AP Biolgoy Adapted from Ms. Gaynor-Day. What’s the point?. The point is to make ATP !. ATP. Fermentation. Cellular respiration Relies on oxygen to produce ATP Oxygen is needed to accept electrons at the end of the ETC

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Cellular Respiration: Fermentation Ch. 9

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  1. Cellular Respiration: FermentationCh. 9 Ms. Springstroh AP Biolgoy Adapted from Ms. Gaynor-Day

  2. What’s thepoint? The pointis to makeATP! ATP

  3. Fermentation • Cellular respiration • Relies on oxygen to produce ATP • Oxygen is needed to accept electrons at the end of the ETC • oxidative phosphorylation (a method of producing ATP) = chemiosmosis + ETC • Requires O2 • In the absence of O2, oxidative phosphorylation, which produces a large amount of ATP, cannot occur • Fermentation enables some cells to produce more ATP (energy!) without the use of oxygen (O2)

  4. Reminder: Glycolysis… • Can produce ATP with or without oxygen, in aerobic or anaerobic conditions • When O2 is absent, glycolysis and fermentation both produce sufficient ATP

  5. Fermentation • Process of generating ATP (energy!) and organic molecules from sugars. Occurs in the absence of oxygen. • Involves glycolysis & reactions that regenerate NAD+ from NADH • NAD+ is regenerated when electrons from NADH are transferred to pyruvate (instead of to the ETC, which happens under aerobic conditions) • Two types: • Alcohol fermentation • Lactic acid fermentation

  6. Alcohol Fermentation • Pyruvate (from glycolysis) is converted to ethanol (ethyl alcohol) in two steps • Step 1: release CO2 from pyruvate • Pyruvate then becomes acetaldehyde • Step 2: Acetaldehyde accepts e-’s (gets reduced) from NADH  ethanol • Now NAD+ has been regenerated  glycolysis can continue, as can [minimal] ATP production • GLUCOSE  Pyruvate  Ethanol + CO2 • Ex: bacteria and yeast do this

  7. P1 2 ATP 2 ADP + 2 O – C O C O Glucose Glycolysis CH3 2 Pyruvate 2 NADH 2 NAD+ CO2 2 H H H C C O OH CH3 CH3 2 Acetaldehyde (gets reduced by NADH. It is the oxidizing agent.) 2 Ethanol (a) Alcohol fermentation 2 ATP P1 2 ADP + 2 Glucose Glycolysis O– C O C O 2 NADH 2 NAD+ CH3 O C O H OH C CH3 2 Lactate (b) Lactic acid fermentation

  8. Lactic Acid Fermentation • Pyruvate is reduced directly (in one step) by NADH to form lactate as a waste product • Now NAD+ has been regenerated  glycolysis can continue, as can [minimal] ATP production • NO CO2 is released • Ex #1: fungus and bacteria in dairy industry to make cheese/ yogurt • Ex #2: Human muscle cells

  9. Fermentation and Cellular Respiration Compared • Both fermentation and cellular respiration • produce ATP by harvesting the chemical energy of food • Use glycolysis to oxidize glucose and other organic fuels to pyruvate

  10. Fermentation and cellular respiration • Differ in their final electron acceptor • Cell respiration uses oxygen • Fermentation uses pyruvate (in lactic acid fermentation) or acetaldehyde (in alcohol fermentation) • Cellular respiration • Produces more ATP (~36-38 ATP) • Fermentation • Produces 2 ATP per cycle

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