Download Comparing Fermentation with Anaerobic and

Figure 7.2
Get used to this picture….
Light
energy
ECOSYSTEM
CO2  H2O
Photosynthesis
in chloroplasts
Cellular respiration
in mitochondria
ATP
Heat
energy
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Organic
 O2
molecules
ATP powers
most cellular work
Aerobic Respiration overview
Electron shuttles
span membrane
CYTOSOL
2 NADH
6 NADH
2 NADH
Glycolysis
Glucose
MITOCHONDRION
2 NADH
or
2 FADH2
2
Pyruvate
Pyruvate
oxidation
2 Acetyl CoA
 2 ATP
Maximum per glucose:
2 FADH2
Citric
acid
cycle
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
 2 ATP
 about 26 or 28 ATP
About
30 or 32 ATP
Can you draw this process? Can you explain it?
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Fermentation & anaerobic respiration enable cells
to produce ATP without the use of oxygen
 Most cellular respiration requires O2 to produce ATP
 Without O2, the electron transport chain will cease to
operate
 In that case, glycolysis couples with fermentation or
anaerobic respiration to produce ATP
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 Anaerobic respiration:

uses an electron transport chain with a final electron
acceptor other than O2, for example, sulfate (S has a
similar electronegativity to O)
 Fermentation:
 uses substrate-level phosphorylation instead of an electron
transport chain to generate ATP
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Figure 7.17
Glucose
CYTOSOL
Glycolysis
Pyruvate
No O2 present:
Fermentation
O2 present:
Aerobic cellular
respiration
MITOCHONDRION
Ethanol,
lactate, or
other products
Acetyl CoA
Citric
acid
cycle
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Alcohol fermentation
2 ADP  2 P
Glucose
Lactic acid fermentation
2 ADP  2 P
2 ATP
i
Glycolysis
Glucose
2 ATP
i
Glycolysis
2 Pyruvate
2 NAD
2 NADH
 2 H
2 NAD
2 CO2
2 NADH
 2 H
2 Pyruvate
2 Acetaldehyde
2 Ethanol
2 Lactate
Pathway
Alcohol
Lactic Acid
Substrate
Pyruvate
Pyruvate
Products
CO2, NAD+, EtOH
NAD+, lactate
Examples
Brewing, breadmaking
Yogurt, cheese, muscle cells
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Comparing Fermentation with Anaerobic
and Aerobic Respiration
Aerobic
Products of
glycolysis
Final Electron
Acceptor
# ATP produced
during respiration
Other products
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Anaerobic
Fermentation
• Pyruvate
• 2 ATP (net)
• NAD+ > NADH
• Pyruvate
• 2 ATP (net)
• NAD+ > NADH
• O2
• Not O2, example • Pyruvate,
SO4
acetaldehyde
• 32
• Includes Krebs
& Glycolysis
contribution
• 32 (I think)
• 2, that’s all you
get
• CO2
• H2O
• H2S
• Lactic Acid
• Ethanol
•
•
•
•
Pyruvate
2 ATP (net)
NAD+ > NADH
CO2
Comparing Fermentation with Anaerobic and
Aerobic Respiration
 All use glycolysis (net ATP  2) to oxidize glucose
and harvest chemical energy of food
 In all three, NAD is the oxidizing agent that accepts
electrons during glycolysis
 The processes have different final electron acceptors:
an organic molecule (such as pyruvate or
acetaldehyde) in fermentation and O2 in cellular
respiration
 Cellular respiration produces 32 ATP per glucose
molecule; fermentation produces 2 ATP per glucose
molecule
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 Obligate anaerobes carry out only fermentation or
anaerobic respiration and cannot survive in the
presence of O2
 Facultative anaerobes: can survive using either
fermentation or cellular respiration
 In a facultative anaerobe, pyruvate is a fork in the
metabolic road that leads to two alternative catabolic
routes
© 2014 Pearson Education, Inc.