Cellular Respiration

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Cellular Respiration

• Process that releases energy by breaking down
  food molecules in the presence of oxygen

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Overview of Cellular Respiration

• A. Glycolysis takes place in cytoplasm
• breaks glucose into 2 molecules of pyruvate
  (3carbons each)
• produces a net of 2 ATPs
• B. Krebs cycle -- takes place in mitochondria
• turns pyruvate into carbon dioxide
• produces a net of 2 ATPs
• C. Electron Transport Chain
• takes place in inner membrane of
  mitochondrion
• accepts e-s from A and B via NADH
• at end, e-s are combined with H and
  oxygen to form water
• forms a net of 34 ATPs
• D. Fermentation Pathways
• takes place in cytoplasm
• 2 types alcoholic and Lactic Acid
  Fermentation
• stores most of the energy in chemical bonds
• no production of ATP

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Glycolysis (2 ATP)
No oxygen present (Anaerobic respiration)
Oxygen present (Aerobic respiration)

Fermentation pathways
Krebs Cycle (2 ATP) (Citric Acid Cycle)

• 2 types
• Alcoholic fermentation
• Lactic Acid fermentation

found in yeasts and a few other microorganisms
Electron Transport Chain (34 ATP)
found in most heterotrophs
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No Oxygen

• Fermentation aside from the original 2 ATPs
  made during glycolysis, the only energy produced
  is that which is in the bonds of
• ethyl alcohol - C2H6O lactic acid C3H5O3
• Uses bread making, wine, beer, gasohol

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Lactic Acid Formation

• Occurs when no oxygen is present
• Causes the burn you feel in muscles from over
  exertion (build up of lactic acid in muscles)
• No ATP is formed

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Figure 9.17a Fermentation
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Figure 9.17b Fermentation
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Oxygen Present

• Oxygen acts as final electron acceptor again, so
  molecules can be broken down into smaller
  particles efficiently and continuously
• Called Aerobic Respiration
• Occurs in the mitochondria
• Produces 36 ATP from 1 glucose molecule

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Figure 9.6 An overview of cellular respiration
(Layer 1)
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Figure 9.6 An overview of cellular respiration
(Layer 2)
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Figure 9.6 An overview of cellular respiration
(Layer 3)
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Figure 9.16 Review how each molecule of glucose
yields many ATP molecules during cellular
respiration
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Amount of ATPs Formed

• Glycolysis 2 ATP
• Anaerobic Respiration
• Fermentation 0 ATP Aerobic
  Respiration
• Total ATP 2 Krebs Cycle 2 ATP
• 
  ETC 34 ATP
• Total ATP
  38

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Comparison of Photosynthesis and Cellular
Respiration

• Occurs in producers (autotrophs)
• Reactions take place in chloroplasts
• Pathway
• 1. Light reactions
• (light dependent)
• 2. Dark reactions
• (light independent)
• Final results
• CO2 and H2O used,
• Glucose and
• O2 is byproduct

• Occurs in ALL organisms (autotrophs and
  heterotrophs)
• Reactions take place in cytoplasm and in
  mitochondria
• Pathway
• 1. Glycolysis
• -- in cytoplasm
• 2. Anaerobic or Aerobic
• (no oxygen or oxygen)
• -- in mitochondria
• Final results
• no O2 fermentation - 2 ATP
• O2 oxidative respiration 38 ATP
• (H2O made, CO2 is byproduct)