The document outlines the key stages of cellular respiration within mitochondria when oxygen is present. It discusses how pyruvate is oxidized to acetyl CoA which enters the citric acid cycle in the mitochondrial matrix. The citric acid cycle converts the acetyl groups to CO2 while producing ATP, NADH, and FADH2. The electron transport chain uses NADH and FADH2 to establish a hydrogen ion gradient across the inner mitochondrial membrane, allowing ATP synthase to produce ATP through chemiosmosis. The maximum ATP yield from completely oxidizing one glucose molecule is approximately 30 ATP.

2. UNIT A: Cell Biology
Chapter 2: The Molecules of Cells
Chapter 3: Cell Structure and Function
Chapter 4: DNA Structure and Gene
Expression
Chapter 5: Metabolism: Energy and
Enzymes
Chapter 6: Cellular Respiration:
Section 6.4
Chapter 7: Photosynthesis

3. UNIT A Chapter 6: Cellular Respiration
Chapter 6: Cellular Respiration
In this chapter you will learn about the many chemical reactions,
known as cellular respiration, that break down molecules such as
glucose to produce the ATP that fuels physical activities.
Why are there differences
between the aerobic and
anaerobic pathways?
How is the energy of a
glucose molecule harvested by
a cell?
How are other organic
nutrients, such as proteins and
fats, used as energy?
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4. UNIT A Chapter 6: Cellular Respiration Section 6.4
6.4 Inside the Mitochondria
When oxygen is present, the final reactions of cellular
respiration occur: preparatory reaction, citric acid cycle, and
electron transport chain reactions.
•Preparatory (prep) reaction occurs in the mitochondrial
matrix and is the oxidation of pyruvate to acetyl CoA, which
enters the citric acid cycle
For each glucose, two pyruvates are oxidized to two acetyl CoA.
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5. UNIT A Chapter 6: Cellular Respiration
Section 6.4
Citric Acid Cycle
The citric acid cycle occurs in the matrix and is a cyclical
pathway that converts the acetyl groups to CO2.
•ATP, NADH, and FADH2 are produced
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From Figure 6.8 Citric Acid Cycle.

6. UNIT A Section 6.4
Citric Acid Cycle
• To start, acetyl-CoA joins with a C4 to form a C6
• During the cycle, each acetyl from the prep reaction is
released as two CO2, oxidations produce NADH + H+ and
FADH2, and substrate-level ATP synthesis occurs
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Chapter 6: Cellular Respiration
From Figure 6.8 Citric Acid Cycle.

7. UNIT A Chapter 6: Cellular Respiration
Section 6.4
Inputs and Outputs of the Citric Acid Cycle
By the end of the citric acid cycle, the six carbons originally
in glucose have become part of six CO2 molecules.
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8. UNIT A Chapter 6: Cellular Respiration
Section 6.4
Electron Transport/ATP Synthesis
The electron transport chain is in the cristae of
mitochondria.
•Electrons are passed along a series of carriers
•High energy e− enter the system and low-energy e−exit
•NADH + H + becomes NAD+ and FADH2 becomes FAD +
•Energy is captured in the form of
a hydrogen ion gradient
•O2 receives e− that exit and react
with H+ to form H2O
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From Figure 6.9 The electron
transport chain.

9. UNIT A Chapter 6: Cellular Respiration
Section 6.4
From Figure 6.9 The
electron transport chain.
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10. UNIT A Chapter 6: Cellular Respiration
Section 6.4
Organization of Cristae
The components of the electron transport chain have a
specific arrangement in the cristae of the mitochondria.
•H+ ions are pumped from the matrix to the intermembrane
space. This produces an unequal distribution of H+ ions,
called an electrochemical gradient
•The H+ move back from the intermembrane space to the
matrix by passing through the ATP synthase complex. This
causes the enzyme complex to produce ATP from ADP and
phosphate.
•ATP synthesis is said to occur by chemiosmosis
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11. UNIT A Chapter 6: Cellular Respiration
Section 6.4
Organization of Cristae
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Figure 6.10 Organization
and function of the
electron transport chain.

12. UNIT A Chapter 6: Cellular Respiration
Section 6.4
Energy Yield from Cellular Respiration
The maximum ATP yield from the complete oxidation of
glucose can be calculated.
•Glycolysis (cytoplasm): 2 ATP
•Citric acid cycle (matrix): 2 ATP
•Electron transport chain and chemiosmosis: 26 to 28 ATP
Experimental observations show:
•2-3 ATP per NADH in electron transport chain
•1-2 ATP per FADH2 in electron transport chain
In many cells, NADH produced in the cytoplasm by
glycolysis requires ATP for transport into the mitochondria.
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13. UNIT A Chapter 6: Cellular Respiration
Section 6.4
Energy Yield from Cellular Respiration
Figure 6.11
Accounting
of the maximum
energy yield per
glucose molecule
breakdown.
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14. UNIT A Section 6.4
Efficiency of Cellular Respiration
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Chapter 6: Cellular Respiration
To determine how much of the energy in glucose becomes
available to the cell:
•Difference in energy between reactants (glucose and O2) and
products (CO2 and H2O) = 686 kcal
•Breaking of 30 phosphate bonds in the conversion of 30 ATP
to 30 ADP + 30 phosphates = 219 kcal
Therefore, 219/686, or 32%, of available energy is transferred
from glucose to ATP. The remaining energy dissipates as heat.

15. UNIT A Section 6.4
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Chapter 6: Cellular Respiration
Check Your Progress
1. Explain the relationship between the metabolic
pathways within the mitochondria with glycolysis.
2. Calculate the number of NADH, FADH2, and ATP
molecules produced by each stage of cellular
respiration per glucose molecule.
3. Discuss why there is variation in the number of ATP
molecules produced per glucose.

16. UNIT A Section 6.4
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Chapter 6: Cellular Respiration

17. UNIT A Section 6.4
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Chapter 6: Cellular Respiration

18. UNIT A Section 6.4
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Chapter 6: Cellular Respiration