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Interest Grabber

Feel the Burn

Do you like to run, bike, or swim? These all are good ways to exercise. When you exercise, your body uses oxygen to get energy from glucose,a six-carbon sugar.

Section 9-1

1. How does your body feel at the start of exercise, such as a long, slowrun? How do you feel 1 minute into the run; 10 minutes into the run?

2. What do you think is happening in your cells to cause the changesin how you feel?

3. Think about running as fast as you can for 100 meters. Could youkeep up this pace for a much longer distance? Explain your answer.

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Section Outline

9–1 Chemical PathwaysA. Chemical Energy and Food

B. Overview of Cellular Respiration

C. Glycolysis

1. ATP Production

2. NADH Production

D. Fermentation

1. Alcoholic Fermentation

2. Lactic Acid Fermentation

Section 9-1

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Glucose

Glycolysis Krebs cycle

Electrontransport

Fermentation (without oxygen)

Alcohol or lactic acid

Chemical Pathways

Section 9-1

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GlucoseGlycolysis

Cytoplasm

Pyruvic acid

Electrons carried in NADH

Krebs Cycle

Electrons carried in

NADH and FADH2 Electron

Transport Chain

Mitochondrion

Figure 9–2 Cellular Respiration: An Overview

Mitochondrion

Section 9-1

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Glucose

To the electron transport chain

Figure 9–3 Glycolysis

Section 9-1

2 Pyruvic acid

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Glucose

To the electron transport chain

Figure 9–3 Glycolysis

Section 9-1

2 Pyruvic acid

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Glucose

To the electron transport chain

Figure 9–3 Glycolysis

Section 9-1

2 Pyruvic acid

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Glucose Pyruvic acidLactic acid

Figure 9–4 Lactic Acid Fermentation

Section 9-1

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Glucose Pyruvic acidLactic acid

Figure 9–4 Lactic Acid Fermentation

Section 9-1

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Glucose Pyruvic acidLactic acid

Figure 9–4 Lactic Acid Fermentation

Section 9-1

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Interest Grabber

Rolling and Folding

Some of the steps in cellular respiration take place in the membrane inside the cell structure called the mitochondrion, which has a folded inner membrane. What purpose do these folds serve?

To find out the answer to this question, perform this activity.

Section 9-2

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Interest Grabber continued

1. Obtain two sheets of paper and a metric ruler. What is the surface area of the paper?

2. Roll one sheet of paper into a tube lengthwise. What is the surface area of the rolled paper?

3. Fold the second sheet of paper into a fan. Then, roll the firstsheet of paper around the folded paper so it is inside the rolled paper.What has happened to the surface area of the inside of the rolled paper?

4. What would be the value of increasing the surface area of the membrane inside a mitochondrion?

Section 9-2

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Section Outline

9–2 The Krebs Cycle and Electron TransportA. The Krebs Cycle

B. Electron Transport

C. The Totals

D. Energy and Exercise

1. Quick Energy

2. Long-Term Energy

E. Comparing Photosynthesis and Cellular Respiration

Section 9-2

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Flowchart

Section 9-2

Glucose(C6H1206)

+Oxygen

(02)

GlycolysisKrebsCycle

ElectronTransport

Chain

Carbon Dioxide

(CO2)+

Water(H2O)

Cellular Respiration

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Citric Acid Production

Figure 9–6 The Krebs Cycle

Section 9-2

Mitochondrion

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Citric Acid Production

Figure 9–6 The Krebs Cycle

Section 9-2

Mitochondrion

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Figure 9–7 Electron Transport Chain

Section 9-2

Electron TransportHydrogen Ion Movement

ATP Production

ATP synthase

Channel

Inner Membrane

Matrix

Intermembrane Space

Mitochondrion

Video Contents

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Aerobic Respiration

Glycolysis

Krebs Cycle, Part 1

Krebs Cycle, Part 2

Electron Transport Chain, Part 1

Electron Transport Chain, Part 2

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Video 1

Aerobic Respiration

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Video 2

Glycolysis

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Video 3

Krebs Cycle, Part 1

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Video 4

Krebs Cycle, Part 2

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Video 5

Electron Transport Chain, Part 1

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Video 6

Electron Transport Chain, Part 2

Links from the authors on Creatine

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Interactive test

For links on cellular respiration, go to www.SciLinks.org and enter the Web Code as follows: cbn-3091.

For links on the Krebs cycle, go to www.SciLinks.org and enter the Web Code as follows: cbn-3092.

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Interest Grabber Answers

1. How does your body feel at the start of exercise, such as a long, slowrun? How do you feel 1 minute into the run; 10 minutes into the run?Students may answer that they feel no fatigue at the start of a run; however, after 1 minute and more so after 10 minutes, they are breathing hard, their heart rate has increased significantly, and their muscles may hurt.

2. What do you think is happening in your cells to cause the changesin how you feel?Students may say that the increase in heart rate and breathing rate are a response that gets extra oxygen to the cells. The pain may be attributed to the cells becoming fatigued.

3. Think about running as fast as you can for 100 meters. Could youkeep up this pace for a much longer distance? Explain your answer.Students may know that very high levels of performance can be sustained only very briefly even among the best of athletes. Students may say that the body runs out of readily available energy, food, or oxygen, or that the body builds up too many waste products in the cells.

Interest Grabber Answers

1. Obtain two sheets of paper and a metric ruler. What is the surface area of the paper? The area will vary depending on the size of paper used. A sheet of notebook paper has an area of approximately 600 cm 3.

2. Roll one sheet of paper into a tube lengthwise. What is the surface area of the rolled paper?The surface area is the same as the original sheet of paper.

3. Fold the second sheet of paper into a fan. Then, roll the firstsheet of paper around the folded paper so it is inside the rolled paper.What has happened to the surface area of the inside of the rolled paper?The surface area has increased (surface area of rolled paper + surface area of folded paper).

4. What would be the value of increasing the surface area of the membrane inside a mitochondrion?Increasing the surface area increases the amount of space where chemical reactions can take place.

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