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PowerPoint Lectures for Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

Chapter 9

Cellular Respiration: Harvesting Chemical Energy

Energy Flow

Concept 9.1

Catabolic Pathways

Oxidize organic fuels

Energy

Catabolic pathways yield energy due to the transfer of electrons
Redox Reactions: Oxidation and Reduction

Na + Cl Na+ + Cl–

becomes oxidized
(loses electron)

becomes reduced
(gains electron)

Catabolic pathways yield energy due to the transfer of electrons
Redox Reactions: Oxidation and Reduction

Na + Cl Na+ + Cl–

becomes oxidized
(loses electron)

LEO

GER

becomes reduced
(gains electron)

Catabolic pathways yield energy due to the transfer of electrons
Redox Reactions: Oxidation and Reduction

Na + Cl Na+ + Cl–

becomes oxidized
(loses electron)

LEO the tiger says GER

LEO

GER

becomes reduced
(gains electron)

Incompletely exchange electrons

CH4

Methane
(reducing
agent)

Oxygen
(oxidizing
agent)

Carbon dioxide

Water

2O2

CO2

Energy

2 H2O

becomes oxidized

becomes reduced

Reactants

Products

Figure 9.3

During cellular respiration

C6H12O6 + 6O2 6CO2 + 6H2O + Energy

becomes oxidized

becomes reduced

LEO the tiger says GER

Cellular respiration oxidizes glucose in a series of steps

Glucose  ?  Oxygen

Cellular respiration oxidizes glucose in a series of steps

Glucose  ?  Oxygen

NAD+, a coenzyme

Figure 9.4

NAD+, a coenzyme

Figure 9.4

NAD+, a coenzyme

Figure 9.4

1. 2 Hydrogen atoms removed by dehydrogenase enzyme

NAD+, a coenzyme

Figure 9.4

2 Hydrogen atoms removed by dehydrogenase enzyme
2 electrons (e-) and 1 proton (H+) transferred to NAD+ NADH
Other proton release into surrounding solution

Overview of Cellular Respiration

Food --------------> NAD+ --------> NADH ------> e- transport chain  O2

Transferred

# e-

# H+

# e- ?

Enzyme?

# e- pulled

# H pulled

Overview of Cellular Respiration

Food --------------> NAD+ --------> NADH ------> e- transport chain  O2

2e-

1H+

2 e-

Dehydrogenase

2 e-

-What is Oxidized?

-What is Reduced?

Mitochondria Structure!

Outer Membrane
Intermembrane Space
Inner Membrane

Cristae

Matrix

The Stages of Cellular Respiration: A Preview

Cellular Respiration- 3 metabolic stages

Glycolysis

Citric Acid Cycle

Oxidative Phosphorylation

Occurs in the cytoplasm

Oxidizes glucose to pyruvate

Stage 1: Glycolysis

Glycolysis consists of two major phases:

1. Energy investment phase

2. Energy payoff phase

1. Energy Investment Phase

Glucose

ATP

_______

Total ATP used?

1. Energy Payoff Phase

2 NADH

2 ATP

2 Pyruvate

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?

Stage 2: Citric Acid Cycle

Before the citric acid cycle can begin

Pyruvate  Acetyl CoA

Before the citric acid cycle can begin

Pyruvate  Acetyl CoA

Citric Acid Cycle

Produce:

-NADH/FADH2

-CO2

-ATP

Citric Acid Cycle

Produce:

-NADH/FADH2

-CO2

-ATP

Citric Acid Cycle

Produce:

-NADH/FADH2

-CO2

-ATP

Citric Acid Cycle

Produce:

-NADH/FADH2

-CO2

-ATP

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

Concept 9.4

Oxidative Phosphorylation:
NADH and FADH2:

Donate electrons to the electron transport chain

Electron transport  inner membrane

Electron Transport Chain

1. NADH + FADH2 electrons 2. electron transport chain

 3. O2  4. O2 + 2H+ = H20

Electron Transport Chain

 5. H+ pumped through electron transport chain proteins from matrix to intermembrane space

 6. H+ diffuse back into matrix through ATP Synthase = ATP!!!

Electron Transport Chain/ Ox. Phosphorylation

ATP Synthase

Rotor

Stator

Rod

Knob

(Catalytic sites)

Certain poisons interrupt cellular respiration

Figure 6.11

Energy flow during respiration:

Glucose

NAD+  NADH

e- transport chain = proton-motive force

ATP

3 main metabolic processes

Concept 9.5

Fermentation vs. Cellular respiration

= Cells produce ATP without the use of oxygen

Alcohol Fermentation

4e-

2H+

Lactic Acid Fermentation

4e-

2H+

Pyruvate is a key juncture in catabolism

The Evolutionary Significance of Glycolysis

Glycolysis

Occurs in nearly all organisms

Probably evolved in ancient prokaryotes before there was oxygen in the atmosphere

Concept 9.6

Regulation of Cellular Respiration via Feedback Mechanisms

Cellular respiration

Is controlled by an allosteric enzymes in glycolysis and the citric acid cycle

Control of cellular respiration in glycolysis

–

Review Ch. 9

Ch. 9 Cellular Respiration
Reactants and Products?
How are electrons pulled from Glucose?

Dehydrogenase, NAD+, NADH

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

Review

Fermentation no O2
Alcohol and Lactic Acid
Carbs., fats and proteins can be used in C.R.
Phosphofructokinase

Certain poisons interrupt cellular respiration

Figure 6.11