1. Copyright Pearson Prentice Hall
9-1 Chemical Pathways
Photo Credit: Duomo Photography, Inc.
Copyright Pearson Prentice Hall

2. Copyright Pearson Prentice Hall
Both plant and animal cells carry out the final stages of cellular respiration in the mitochondria.
Animal Cells
Outer membrane
Intermembrane space
Mitochondrion
Inner membrane
Photo Credits: left: ©Bob Gurr/DRK Photo; middle bottom: ©John Durham/Science Photo Library/Photo Researchers, Inc. ; middle top: ©Ron Boardman/Stone; right: ©Keith Porter/Photo Researchers, Inc.
Matrix
Plant Cells
Copyright Pearson Prentice Hall

3. Chemical Energy and Food
One gram of the sugar glucose (C6H12O6), when burned in the presence of oxygen, releases 3811 calories of heat energy.
A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.
Copyright Pearson Prentice Hall

4. Overview of Cellular Respiration
Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.
Copyright Pearson Prentice Hall

5. Overview of Cellular Respiration
The equation for cellular respiration is:
6O2 + C6H12O6 → 6CO2 + 6H2O + Energy
oxygen + glucose → carbon dioxide + water + Energy
Copyright Pearson Prentice Hall

6. Overview of Cellular Respiration
Electrons carried in NADH
Electrons carried
in NADH and
FADH2
Pyruvic acid
Glucose
Glycolysis
Cytoplasm
Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place inside the mitochondria.
Mitochondrion
Copyright Pearson Prentice Hall

7. Copyright Pearson Prentice Hall
Glycolysis
This gives the cell a net gain of 2 ATP molecules.
2 ATP
2 ADP
4 ADP
4 ATP
Glucose
2 Pyruvic
acid
Copyright Pearson Prentice Hall

8. Copyright Pearson Prentice Hall
Glycolysis
The Advantages of Glycolysis
The process of glycolysis is so fast that cells can produce thousands of ATP molecules in a few milliseconds.
Glycolysis does not require oxygen= Anaerobic
Copyright Pearson Prentice Hall

9. Copyright Pearson Prentice Hall
Fermentation
Fermentation
When oxygen is not present, glycolysis is followed by a different pathway. The combined process of this pathway and glycolysis is called fermentation.
Fermentation releases energy from food molecules by producing ATP in the absence of oxygen.
Copyright Pearson Prentice Hall

10. Copyright Pearson Prentice Hall
Fermentation
Alcoholic Fermentation
Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes.
Copyright Pearson Prentice Hall

11. Copyright Pearson Prentice Hall
Fermentation
Lactic Acid Fermentation
In many cells, pyruvic acid that accumulates as a result of glycolysis can be converted to lactic acid.
This type of fermentation is called lactic acid fermentation. It regenerates NAD+ so that glycolysis can continue.
Copyright Pearson Prentice Hall

12. 9-2 The Krebs Cycle and Electron Transport
Oxygen is required for the final steps of cellular respiration.
Because the pathways of cellular respiration require oxygen, they are aerobic.
Copyright Pearson Prentice Hall

13. Copyright Pearson Prentice Hall
The Krebs Cycle
During the Krebs cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions.
Copyright Pearson Prentice Hall

14. Copyright Pearson Prentice Hall
Electron Transport
Electron Transport
The electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP into ATP and water is formed.
Copyright Pearson Prentice Hall

15. Copyright Pearson Prentice Hall
Electron Transport
At the end of the chain, an enzyme combines these electrons with hydrogen ions and oxygen to form water.
Copyright Pearson Prentice Hall

16. Copyright Pearson Prentice Hall
Electron Transport
As it rotates, the enzyme grabs a low-energy ADP, attaching a phosphate, forming high-energy ATP.
Channel
ATP synthase
The electron transport chain uses high-energy electrons from the Krebs cycle to convert ADP to ATP.
ATP
Copyright Pearson Prentice Hall

17. Copyright Pearson Prentice Hall
The Totals
The Totals
Glycolysis produces just 2 ATP molecules per molecule of glucose.
The complete breakdown of glucose through cellular respiration, including glycolysis, results in the production of 36 molecules of ATP.
Copyright Pearson Prentice Hall

18. Copyright Pearson Prentice Hall
The Totals
The complete breakdown of glucose through cellular respiration, including glycolysis, results in the production of 36 molecules of ATP.
Copyright Pearson Prentice Hall

19. Comparing Photosynthesis and Cellular Respiration
The energy flows in photosynthesis and cellular respiration take place in opposite directions.
Copyright Pearson Prentice Hall

20. Copyright Pearson Prentice Hall
9-1
Copyright Pearson Prentice Hall

21. Copyright Pearson Prentice Hall
9-1
The raw materials required for cellular respiration are
carbon dioxide and oxygen.
glucose and water.
glucose and oxygen.
carbon dioxide and water.
Copyright Pearson Prentice Hall

22. Copyright Pearson Prentice Hall
9-1
Glycolysis occurs in the
mitochondria.
cytoplasm.
nucleus.
chloroplasts.
Copyright Pearson Prentice Hall

23. Copyright Pearson Prentice Hall
9-1
The net gain of ATP molecules after glycolysis is
3 ATP molecules.
2 ATP molecules.
3 pyruvic acid molecules.
4 pyruvic acid molecules
Copyright Pearson Prentice Hall

24. Copyright Pearson Prentice Hall
9-1
Fermentation releases energy from food molecules in the absence of
oxygen.
glucose.
NADH.
alcohol.
Copyright Pearson Prentice Hall

25. Copyright Pearson Prentice Hall
9-1
The first step in fermentation is always
lactic acid production.
the Krebs cycle.
glycolysis.
alcohol production.
Copyright Pearson Prentice Hall

26. END OF SECTION