Cellular Respiration
1
Cellular Respiration


A catabolic (molecule breakdown), exergonic
(energy tranformation), oxygen (O2) requiring
process that uses energy extracted from
macromolecules (glucose) to produce energy
(ATP) and water (H2O).
ATP (Adenosine Triphosphate) Energy is held
in the phosphate bonds.
glucose
ATP
C6H12O6 + 6O2  6CO2 + 6H2O + energy
2
Question:

In what kinds organisms does cellular
respiration take place?
3
Plants and Animals


Plants - Autotrophs: self-producers.
Animals - Heterotrophs: consumers.
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Mitochondria

Organelle where cellular respiration takes
place.
Outer
membrane
Inner
membrane space
Matrix
Cristae
Inner
membrane
5
Breakdown of Cellular
Respiration

3 main parts (reactions).
1. Glycolysis (splitting of sugar)
a. cytosol, just outside of mitochondria.
2. Krebs Cycle (Citric Acid Cycle)
a. mitochondrial matrix
3. Electron Transport Chain (ETC) and
Oxidative Phosphorylation
a. Also called Chemiosmosis
b. inner mitochondrial membrane
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1. Glycolysis (Anaerobic)


Occurs in the cytosol just outside of
mitochondria.
Two phases:
A. Energy investment phase
a. Preparatory phase.
B. Energy yielding phase
a. Energy payoff phase.
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1. Glycolysis
A. Energy Investment Phase:
Glucose (6C)
2ATP
C-C-C-C-C-C
2 ATP - used
0 ATP - produced
0 NADH - produced
2ADP + P
Glyceraldehyde phosphate (2 - 3C)
(G3P or GAP)
C-C-C
C-C-C
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1. Glycolysis
B. Energy Yielding Phase
Glyceraldehyde phosphate (2 - 3C)
(G3P or GAP)
4ADP + P
4ATP
GAP
GAP
C-C-C C-C-C
0 ATP - used
4 ATP - produced
2 NADH - produced
Pyruvate (2 - 3C)
(PYR)
C-C-C C-C-C
(PYR) (PYR)
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1. Glycolysis

Total Net Yield Products
2 - 3C-Pyruvate (PYR)
2 - ATP (Substrate-level
Phosphorylation)
2 - NADH
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Substrate-Level
Phosphorylation

ATP is formed when an enzyme transfers a
phosphate group from a substrate to
ADP.
Enzyme
Example:
PEP to PYR
Substrate
(PEP)
Product
(Pyruvate)
OC=O
C-OCH2
OC=O
C=O
CH2
P
P
P
Adenosine
ADP
P P
P
Adenosine
ATP
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Fermentation



Occurs in cytosol when “NO Oxygen” is
present (called anaerobic).
Remember: glycolysis is part of
fermentation.
Two Types:
1. Alcohol Fermentation
2. Lactic Acid Fermentation
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Alcohol Fermentation

C
C
C
C
C
C
glucose
Plants and Fungi
2ADP
+2 P
beer and wine
2ATP
2NADH
C
C
C
Glycolysis
2 NAD+

2NADH
2 Pyruvic
acid
2 NAD+
C
C
2 Ethanol
2CO2
released
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Alcohol Fermentation

End Products: Alcohol fermentation
2 - ATP (substrate-level phosphorylation)
2 - CO2
2 - Ethanol’s
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Lactic Acid Fermentation

Animals (pain in muscle after a workout).
C
C
C
C
C
C
2ADP
+2 P
2ATP
2NADH
C
C
C
Glycolysis
2 NAD+
2NADH
2 Pyruvic
acid
2 NAD+
C
C
C
2 Lactic
acid
Glucose
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Lactic Acid Fermentation

End Products: Lactic acid fermentation
2 - ATP (substrate-level phosphorylation)
2 - Lactic Acids
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3. Krebs Cycle (Citric Acid Cycle)



Location: mitochondrial matrix.
Acetyl CoA (2C) bonds to Oxalacetic acid
(4C - OAA) to make Citrate (6C).
It takes 2 turns of the krebs cycle to
oxidize 1 glucose molecule.
Mitochondrial
Matrix
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3. Krebs Cycle (Citric Acid Cycle)
1 Acetyl CoA (2C)
OAA (4C)
Citrate (6C)
FADH2
Krebs
Cycle
2 CO2
(one turn)
3 NAD+
FAD
3 NADH
ATP
ADP + P
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3. Krebs Cycle (Citric Acid Cycle)
2 Acetyl CoA (2C)
Citrate (6C)
OAA (4C)
2 FADH2
Krebs
Cycle
4 CO2
(two turns)
6 NAD+
2 FAD
6 NADH
2 ATP
2 ADP +
P
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3. Krebs Cycle (Citric Acid Cycle)

Total net yield (2 turns of krebs
cycle)
1. 2 - ATP (substrate-level
phosphorylation)
2. 6 - NADH
3. 2 - FADH2
4. 4 - CO2
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4. Electron Transport Chain (ETC) and
Oxidative Phosphorylation
(Chemiosmosis)



Location: inner mitochondrial membrane.
Uses ETC (cytochrome proteins) and ATP
Synthase (enzyme) to make ATP.
ETC pumps H+ (protons) across innermembrane
(lowers pH in innermembrane space).
Inner
Mitochondrial
Membrane
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4. Electron Transport Chain (ETC) and
Oxidative Phosphorylation
(Chemiosmosis)




The H+ then move via diffusion (Proton
Motive Force) through ATP Synthase to make
ATP.
All NADH and FADH2 converted to ATP during
this stage of cellular respiration.
Each NADH converts to 3 ATP.
Each FADH2 converts to 2 ATP (enters the ETC
at a lower level than NADH).
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4. Electron Transport Chain (ETC) and
Oxidative Phosphorylation
(Chemiosmosis)
Outer
membrane
Inner
membrane space
Matrix
Cristae
Inner
membrane
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4. ETC and Oxidative Phosphorylation
(Chemiosmosis for NADH)
higher H+
concentration
Intermembrane Space
1H+
E
2H+
3H+
T
C
NAD+
(Proton Pumping)
Matrix
ATP
Synthas
e
Inner
Mitochondrial
Membrane
O2 H O
2
2H+ + 1/2
NADH
+ H+
H+
ADP + P
H+
ATP
lower H+
concentration
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4. ETC and Oxidative Phosphorylation
(Chemiosmosis for FADH2)
higher H+
concentration
Intermembrane Space
1H+
E
T
FADH2
+ H+
FAD+
(Proton Pumping)
Matrix
2H+
C
2H+ +
1/2O2
H+
ATP
Synthas
e
Inner
Mitochondrial
Membrane
H2O
ADP + P
H+
ATP
lower H+
concentration
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TOTAL ATP YIELD
1. 04 ATP - substrate-level
phosphorylation
2. 34 ATP - ETC & oxidative
phosphorylation
38 ATP - TOTAL YIELD
ATP
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Maximum ATP Yield for Cellular
Respiration (Eukaryotes)
Glucose
Cytosol
Glycolysis
2 Acetyl CoA
2 Pyruvate
Mitochondria
Krebs
Cycle
2NADH
2 ATP
6NADH
2FADH2
(substrate-level
phosphorylation)
2NADH
ETC and Oxidative
Phosphorylation
2 ATP
(substrate-level
phosphorylation)
2ATP
4ATP 6ATP
18ATP
4ATP
36 ATP (maximum per glucose)
2ATP
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