Chapter 9
Cellular Respiration:
Harvesting Chemical Energy
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
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Energy Flow
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Energy Flow
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Concept 9.1
Catabolic Pathways
Oxidize organic fuels
Energy
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• Catabolic pathways yield energy due to the
transfer of electrons
• Redox Reactions: Oxidation and Reduction
becomes oxidized
(loses electron)
Na
+
Cl
Na+
+
becomes reduced
(gains electron)
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Cl–
• Catabolic pathways yield energy due to the
transfer of electrons
• Redox Reactions: Oxidation and Reduction
becomes oxidized
(loses electron)
LEO
Na
+
Cl
Na+
+
becomes reduced
(gains electron)
GER
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Cl–
• Catabolic pathways yield energy due to the
transfer of electrons
• Redox Reactions: Oxidation and Reduction
becomes oxidized
(loses electron)
LEO
Na
+
Cl
Na+
+
becomes reduced
(gains electron)
GER
LEO the tiger says GER
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Cl–
Incompletely exchange electrons
Products
Reactants
becomes
oxidized
CO2 + Energy +
2O2
+
CH4
becomes
reduced
O O
C
O
H
O
O
H
H
H
C
2 H2 O
H
H
Figure 9.3
Methane
(reducing
agent)
Oxygen
(oxidizing
agent)
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Carbon dioxide
Water
During cellular respiration
becomes oxidized
C6H12O6 + 6O2
6CO2 + 6H2O + Energy
becomes reduced
LEO the tiger says GER
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• Cellular respiration oxidizes glucose in a series
of steps
e-
Glucose  ?  Oxygen
e-
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• Cellular respiration oxidizes glucose in a series
of steps
e-
Glucose  ?  Oxygen
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NAD+, a coenzyme
Figure 9.4
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NAD+, a coenzyme
Figure 9.4
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NAD+, a coenzyme
1. 2 Hydrogen atoms removed by dehydrogenase enzyme
Figure 9.4
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NAD+, a coenzyme
1. 2 Hydrogen atoms removed by dehydrogenase enzyme
2. 2 electrons (e-) and 1 proton (H+) transferred to NAD+ NADH
3. Other proton release into surrounding solution
Figure 9.4
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Overview of Cellular Respiration
Enzyme?
# e- pulled
# H pulled
Transferred
# e+
#
H
+
# e- ?
• Food --------------> NAD --------> NADH ------>
e- transport chain  O2
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Overview of Cellular Respiration
Dehydrogenase
2 e2H
2e2 e+
1H
+
• Food --------------> NAD --------> NADH ------>
e- transport chain  O2
-What is Oxidized?
-What is Reduced?
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Mitochondria Structure!
• Outer Membrane
• Intermembrane Space
• Inner Membrane
– Cristae
• Matrix
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The Stages of Cellular Respiration: A Preview
•
Cellular Respiration- 3 metabolic stages
1. Glycolysis
2. Citric Acid Cycle
3. Oxidative Phosphorylation
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1.
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2.
3.
•Stage 1: Glycolysis
•
Occurs in the cytoplasm
•
Oxidizes glucose to pyruvate
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Glycolysis consists of two major phases:
1. Energy investment phase
2. Energy payoff phase
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1. Energy Investment Phase
Glucose
ATP
ATP
_______
Total ATP used?
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1. Energy Payoff Phase
2 NADH
2 ATP
2 ATP
2 Pyruvate
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Total ATP made?
Energy Investment and Payoff Phases
Starting with 1
glucose indicate how
many molecules of
the following are
produced during
glycolysis:
A. Total ATP made
B. Total pyruvate?
C. Total NADH?
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Stage 2: Citric Acid Cycle
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Before the citric acid cycle can begin
Pyruvate  Acetyl CoA
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Before the citric acid cycle can begin
Pyruvate  Acetyl CoA
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Citric Acid Cycle
• Produce:
-NADH/FADH2
-CO2
-ATP
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Citric Acid Cycle
• Produce:
-NADH/FADH2
-CO2
-ATP
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Citric Acid Cycle
• Produce:
-NADH/FADH2
-CO2
-ATP
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Citric Acid Cycle
• Produce:
-NADH/FADH2
-CO2
-ATP
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An overview of the citric acid cycle
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An overview of the citric acid cycle
1. How many of
each of the following
molecules are
produced per turn?
2. How many of
each is made per
glucose molecule?
NADH
FADH2
CO2
ATP
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Concept 9.4
• Oxidative Phosphorylation:
• NADH and FADH2:
– Donate electrons to the electron transport
chain
– Electron transport  inner membrane
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Electron Transport Chain
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Electron Transport Chain
1. NADH + FADH2 electrons 2. electron transport chain
 3. O2  4. O2 + 2H+ = H20
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Electron Transport Chain
 5. H+ pumped through electron transport chain proteins from
matrix to intermembrane space
Copyright
6. H+
diffuse back into matrix through ATP Synthase = ATP!!!
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Electron Transport Chain/ Ox. Phosphorylation
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• ATP
Synthase
Rotor
Stator
Rod
Knob
(Catalytic sites)
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Certain poisons interrupt cellular respiration
Figure 6.11
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• Energy flow during respiration:
Glucose
NAD+  NADH
e- transport chain = proton-motive force
ATP
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3 main metabolic processes
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Concept 9.5
• Fermentation vs. Cellular respiration
= Cells produce ATP without the use of oxygen
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Alcohol Fermentation
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Alcohol Fermentation
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Alcohol Fermentation
4e2H+
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Lactic Acid Fermentation
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Lactic Acid Fermentation
4e2H+
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• Pyruvate is a key juncture in catabolism
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The Evolutionary Significance of Glycolysis
• Glycolysis
– Occurs in nearly all organisms
– Probably evolved in ancient prokaryotes before
there was oxygen in the atmosphere
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Concept 9.6
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Regulation of Cellular Respiration via Feedback
Mechanisms
• Cellular respiration
– Is controlled by an allosteric enzymes in
glycolysis and the citric acid cycle
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Control of cellular respiration in glycolysis
+
–
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–
Review Ch. 9
• Ch. 9 Cellular Respiration
• Reactants and Products?
• How are electrons pulled from Glucose?
– Dehydrogenase, NAD+, NADH
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Review!
• Mitochondrial Structure
• 3 Stages of Cellular Respiration:
1. Glycolysis (glucose 2 pyruvate)
#NADH, #ATP, #CO2, #FADH2?
2. Citric Acid Cycle (pyruvate acetyl CoA)
#NADH, #ATP, #CO2, #FADH2?
3. Oxidative Phosphorylation
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Review
• Fermentation no O2
• Alcohol and Lactic Acid
• Carbs., fats and proteins can be used in C.R.
• Phosphofructokinase
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Certain poisons interrupt cellular respiration
Figure 6.11
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