CELLULAR RESPIRATION
How Cells Release Energy
Cellular Respiration
Anaerobic Cellular Respiration
Aerobic Cellular Respiration
1. Glycolysis
1. Glycolysis
2. Fermentation
3. Krebs Cycle
4. Electron Transport System
Anaerobic Cellular Respiration
1. Glycolysis
2. Fermentation
1. Glycolysis
Takes place in the cytoplasm of all cells
(Sugar Splitting)
C6H12O6
Glucose
2 ADP
2 ATP
2 NAD+
2 NADH
Pyruvate
Pyruvate
2. Fermentation
Alcoholic Fermentation
Pyruvate
2 NADH
Alcohol
2 NAD+
+
CO2
The Significance of fermentation is to regenerate NAD+
from NADH for its continuous role in glycolysis
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
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
Aerobic Cellular Respiration
1. Glycolysis
3. Krebs Cycle: Step a
3. Krebs Cycle
3. Krebs Cycle: Step b
4. Electron Transport System
1. Glycolysis
Takes place in the cytoplasm of all cells
(Sugar Splitting)
C6H12O6
Glucose
2 ADP
2 ATP
2 NAD+
2 NADH
Pyruvate
Pyruvate
The output of Glycolysis
is:
2 ATP
2 NADH
The 2 pyruvates produced by glycolysis in the
cytoplasm are transported into the mitochondrion to
continue aerobic cellular respiration in Krebs cycle
3. Krebs Cycle
Takes place in the mitochondrion
Step a
1 CO2
1 NADH
1st pyruvate
Acetyl group
+
CoA
Acetyl-CoA
CoA
3. Krebs Cycle
Takes place in the mitochondrion
Step a
1 CO2
1 NADH
2nd pyruvate
Acetyl group
+
CoA
Acetyl-CoA
CoA
The output of Krebs Cycle
step a is:
2 CO2
2 NADH
3. Krebs Cycle
Step b
CoA
1st Acetyl-CoA
+
2 CO2
4-C- compound
1 ATP
3 NADH
1 FADH2
6-C-Compound
3. Krebs Cycle
Step b
CoA
2nd Acetyl-CoA
+
2 CO2
4-C- compound
1 ATP
3 NADH
1 FADH2
6-C-Compound
The output of Krebs Cycle
step b is:
2 ATP
4 CO2
6 NADH
2 FADH2
The output of Krebs Cycle
The output of Krebs Cycle
step a is:
2 CO2
2 NADH
step b is:
2 ATP
4 CO2
6 NADH
2 FADH2
The output of Krebs Cycle
both steps is:
2 ATP
6 CO2
8 NADH
2 FADH2
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
An Overview of the Electron Transport System
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.
5. Hydrogen ions build up in the outer compartment
(higher concentration of H+ in the outer compartment
than in the matrix).
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.
The Electron Transport System
Electron Transport System
Most of ATP is produced during ETS
ETS produces 32 ATP
The Overall Equation of CR
C6H12O6 + 6 O2
6 CO2 + 6 H2O + 36 ATP + Heat