Anaerobic Respiration

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Anaerobic Respiration
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During the last stage of cell respiration,
electrons from glucose are passed down the
electron passport chain to the final electron
acceptor, oxygen
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Chemiosmosis couples the electron transport chain
to ATP synthesis
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Aerobic Respiration

• When oxygen is the final electron acceptor, the
  process is called aerobic respiration
• Aerobic occurring in the presence of oxygen

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Anaerobic Respiration

• Some prokaryotes are able to carry out anaerobic
  respiration, respiration in which an inorganic
  molecule other than oxygen (O2) is the final
  electron acceptor.
• For example, some bacteria, called nitrate
  reducers, can transfer electrons to nitrate
  (NO3-) reducing it to nitrite (NO2-).
• Less efficient usually 30-34 ATPs per glucose
  molecule.

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What happens if there is no available electron
acceptor?
Glucose
2 ADP
2 NAD
glycolysis
2 ATP
2 NADH
2 pyruvate
Aerobic respiration The NADH then passes its
high energy e- to the electron transport chain
(becoming NAD again) and eventually to
O2 Anaerobic respiration Without O2, NADH has
nowhere to donate its e- to, NAD cannot be
regenerated, and glycolysis stops
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Anaerobic fermentation

• Fermentation An alternative set of reactions
  that can follow glycolysis in the absence of
  oxygen as a final electron acceptor.
• Extremely inefficient no Krebs cycle, no ETC.
  Glycolysis produces a net of 2 ATPs per glucose
  molecule

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FERMENTATION PATHWAYS ALLOWS CELLS TO REGENERATE
NAD FOR GLYCOLSIS
Fermentation by-product
Intermediate accepts electrons from NADH
2 NAD
2 NADH
2 Pyruvate
Glucose
2 ATP
2 ADP
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LACTIC ACID FERMENTATION OCCURS IN HUMANS
Pyruvate accepts electrons from NADH
2 NAD
2 Lactate
2 NADH
Glucose
2 Pyruvate
2 ADP
2 ATP
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During heavy exercise, ATP production will
switch from aerobic respiration to anerobic
respiration
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ALCOHOL FERMENTATION OCCURS IN YEAST
2 CO2
2 Acetylaldehyde
2 Ethanol
2 NAD
2 NADH
Glucose
2 ATP
2 Pyruvate
2 ADP
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The Stuff of Life