CELLULAR RESPIRATION

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CELLULAR RESPIRATION

• How Cells Release Energy

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Cellular Respiration
Aerobic Cellular Respiration
Anaerobic Cellular Respiration
1. Glycolysis
1. Glycolysis
2. Fermentation
3. Krebs Cycle
4. Electron Transport System
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Anaerobic Cellular Respiration
1. Glycolysis
2. Fermentation
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• Glycolysis
• (Sugar Splitting)

Takes place in the cytoplasm of all cells
C6H12O6 Glucose
2 ATP
2 ADP
2 NAD
2 NADH
Pyruvate
Pyruvate
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2. Fermentation
Alcoholic Fermentation
Pyruvate
2 NADH
2 NAD
Alcohol
CO2

The Significance of fermentation is to regenerate
NAD from NADH for its continuous role in
glycolysis
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2. Fermentation
Lactic Acid Fermentation
Pyruvate
2 NADH
2 NAD
Lactic acid
The Significance of fermentation is to regenerate
NAD from NADH for its continuous role in
glycolysis
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Fermentation does NOT produce additional ATP
The Significance of fermentation is to regenerate
NAD from NADH for its continuous role in
glycolysis
During anaerobic cellular respiration only 2 ATP
are produced from one initial glucose molecule
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Aerobic Cellular Respiration
1. Glycolysis
3. Krebs Cycle Step a
3. Krebs Cycle
3. Krebs Cycle Step b
4. Electron Transport System
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• Glycolysis
• (Sugar Splitting)

Takes place in the cytoplasm of all cells
C6H12O6 Glucose
2 ATP
2 ADP
2 NAD
2 NADH
Pyruvate
Pyruvate
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The output of Glycolysis is 2 ATP 2 NADH
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The 2 pyruvates produced by glycolysis in
the cytoplasm are transported into the
mitochondrion to continue aerobic cellular
respiration in Krebs cycle
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3. Krebs Cycle
Takes place in the mitochondrion
Step a
1 CO2
1 NADH
1st pyruvate
Acetyl group

CoA
CoA
Acetyl-CoA
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3. Krebs Cycle
Takes place in the mitochondrion
Step a
1 CO2
1 NADH
2nd pyruvate
Acetyl group

CoA
CoA
Acetyl-CoA
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The output of Krebs Cycle step a is 2 CO2 2 NADH
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3. Krebs Cycle
CoA

Step b
1st Acetyl-CoA
2 CO2
4-C- compound
1 ATP
3 NADH
1 FADH2
6-C-Compound
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3. Krebs Cycle
CoA

Step b
2nd Acetyl-CoA
2 CO2
4-C- compound
1 ATP
3 NADH
1 FADH2
6-C-Compound
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The output of Krebs Cycle step b is 2 ATP 4
CO2 6 NADH 2 FADH2
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The output of Krebs Cycle step b is 2 ATP 4
CO2 6 NADH 2 FADH2
The output of Krebs Cycle step a is 2 CO2 2 NADH
The output of Krebs Cycle both steps is 2 ATP 6
CO2 8 NADH 2 FADH2
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Summary of energy harvest

• GLYCOLYSIS
• 2 ATP
• 2 NADH
• Krebs Cycle
• 2 ATP
• 6 CO2
• 8 NADH
• 2 FADH2

• 4 ATP can be used for cellular work
• 6 CO2 are released
• Raw materials for electron transport system
• 10 NADH
• 2 FADH2

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An Overview of the Electron Transport System
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The Electron Transport System
1. NADH and FADH2 pass electrons to the first
protein in the electron transport system
(ETS).
 2. Electrons pass from energy carrier to the
next.
 3. With each transfer, energy is released
4. This energy is used to pump hydrogen ions
into the outer compartment of the
mitochondrion.
 
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5. Hydrogen ions build up in the outer
compartment (higher concentration of H in the
outer compartment than in the matrix).
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6. Hydrogen ions flow back across the membrane
through an enzyme (ATP synthase) that
synthesizes ATP
7. The last protein in the ETS finally passes
electrons to oxygen along with hydrogen ions,
generating water.
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The Electron Transport System
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Electron Transport System

• Most of ATP is produced during ETS
• ETS produces 32 ATP

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The Overall Equation of CR

• C6H12O6 6 O2
• 6 CO2 6 H2O 36 ATP Heat