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Cellular Respiration
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Cellular Respiration

A catabolic, exergonic, oxygen (O2) requiring
process that uses energy extracted from
macromolecules (glucose) to produce energy
(ATP) and water (H2O).
C6H12O6 + 6O2  6CO2 + 6H2O + energy
glucose
ATP
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Question:

In what kinds organisms does cellular
respiration take place?
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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
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Redox Reaction


Transfer of one or more electrons from
one reactant to another.
Two types:
1. Oxidation
2. Reduction
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Oxidation Reaction

The loss of electrons from a substance.

Or the gain of oxygen.
Oxidation
C6H12O6 + 6O2 6CO2 + 6H2O +
energy
glucose
ATP
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Reduction Reaction


The gain of electrons to a
substance.
Or the loss of oxygen.
Reduction
C6H12O6 + 6O2 
glucose
6CO2 + 6H2O + energy
ATP
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Breakdown of Cellular
Respiration

Four main parts (reactions).
1. Glycolysis (splitting of sugar)
a. cytosol, just outside of mitochondria.
2. Grooming Phase
a. migration from cytosol to matrix.
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Breakdown of Cellular
Respiration
3. Krebs Cycle (Citric Acid Cycle)
a. mitochondrial matrix
4. Electron Transport Chain (ETC) and
Oxidative Phosphorylation
a. Also called Chemiosmosis
b. inner mitochondrial membrane.
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1. Glycolysis


Occurs in the cytosol just outside of
mitochondria.
Two phases (10 steps):
A. Energy investment phase
a. Preparatory phase (first 5 steps).
B. Energy yielding phase
a. Energy payoff phase (second 5
steps).
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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
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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2. Grooming Phase


Occurs when Oxygen is present (aerobic).
2 Pyruvate (3C) molecules are transported
through the mitochondria membrane to the
matrix and is converted to 2 Acetyl CoA (2C)
molecules.
Cytosol
2 CO2
C
C
C
Matrix
C-C
2 Pyruvate
2 NAD+
2NADH
2 Acetyl CoA
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2. Grooming Phase

End Products: grooming phase
2 - NADH
2 - CO2
2- Acetyl CoA (2C)
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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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Electron Transport Chain
Animation
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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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Eukaryotes
(Have Membranes)
Total ATP Yield
02 ATP - glycolysis (substrate-level phosphorylation)
04 ATP - converted from 2 NADH - glycolysis
06 ATP - converted from 2 NADH - grooming phase
02 ATP - Krebs cycle (substrate-level phosphorylation)
18 ATP - converted from 6 NADH - Krebs cycle
04 ATP - converted from 2 FADH2 - Krebs cycle
36 ATP - TOTAL

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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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Prokaryotes
(Lack Membranes)
Total ATP Yield
02 ATP - glycolysis (substrate-level phosphorylation)
06 ATP - converted from 2 NADH - glycolysis
06 ATP - converted from 2 NADH - grooming phase
02 ATP - Krebs cycle (substrate-level phosphorylation)
18 ATP - converted from 6 NADH - Krebs cycle
04 ATP - converted from 2 FADH2 - Krebs cycle
38 ATP - TOTAL

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Question:

In addition to glucose, what other
various food molecules are use in
Cellular Respiration?
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Catabolism of Various
Food Molecules

Other organic molecules used for fuel.
1. Carbohydrates: polysaccharides
2. Fats: glycerol’s and fatty acids
3. Proteins: amino acids
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