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9-1 Chemical Pathways
Photo Credit: Duomo Photography, Inc.
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9-1 Chemical Pathways
Food serves as a source of raw materials for the cells in the body and as a source of energy.
Animal Cells
Animal
Mitochondrion
Plant
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Plant Cells
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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
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Matrix
Plant Cells
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4. 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.
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5. Overview of Cellular Respiration
What is cellular respiration?
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6. 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.
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7. 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
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8. Overview of Cellular Respiration
Glycolysis takes place in the cytoplasm and is an anaerobic process. The Krebs cycle and electron transport take place in the mitochondria and both are aerobic processes.
Glycolysis
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.
Cytoplasm
Mitochondrion
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9. Overview of Cellular Respiration
Glycolysis must take place first.
anaerobic process (does not require oxygen)
takes place in cytoplasm
splits glucose into two three-carbon molecules
produces two ATP molecules
Glycolysis
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.
Cytoplasm
Mitochondrion
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10. Overview of Cellular Respiration
6H O 2
6CO 6O
mitochondrion
matrix (area enclosed
by inner membrane)
inner membrane
ATP
energy
energy from glycolysis 1 4 3
and
The Krebs cycle transfers energy to an electron transport chain.
takes place in mitochondrial matrix
breaks down three-carbon molecules (pyruvate) from glycolysis
makes a small amount of ATP
releases carbon dioxide
transfers energy-carrying molecules
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
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11. Overview of Cellular Respiration
6H O 2
6CO 6O
mitochondrion
matrix (area enclosed
by inner membrane)
inner membrane
ATP
energy
energy from glycolysis 1 4 3
and
The electron transport chain produces a large amount of ATP.
takes place in inner membrane
energy transferred to electron transport chain
oxygen enters process
ATP produced
Water is released as a waste product
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
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12. Electron Transport Chain
Flowchart
Section 9-2
Cellular Respiration
Carbon
Dioxide
(CO2) +
Water
(H2O)
ATP
Glucose (C6H1206) +
Oxygen (02)
Glycolysis
Krebs Cycle
Electron Transport Chain

13. Total ENERGY Yield Glycolysis 2 ATP Krebs Cycle 2 ATP ETC  32 ATP
Total 36 ATP

14. Overview of Cellular Respiration
Cellular respiration is like a mirror image of photosynthesis.
The reactants in photosynthesis are the same as the products of cellular respiration.
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.
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15. Overview of Cellular Respiration
The equation for cellular respiration is:
6O2 + C6H12O6 → 6CO2 + 6H2O + Energy
oxygen + glucose → carbon dioxide + water + Energy
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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.
So what happens is no O2 is available?
Cellular respiration stops…
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17. Aerobic vs. Anaerobic Anaerobic DOES NOT require oxygen
Simple
fast
produces smaller amounts of energy (ATP)
Aerobic requires oxygen
Yields large amounts of energy
What is this energy molecule?
ATP, ATP, ATP

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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 is the process that allows glycolysis to continue to ATP when oxygen is not available.
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Fermentation
What are the two main types of fermentation?
Alcohol fermentation
Lactic acid fermentation
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Fermentation
Alcoholic Fermentation
Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol (to make alcoholic beverages) and carbon dioxide (what makes bread rise) as wastes.
The equation for alcoholic fermentation after glycolysis is:
pyruvic acid + NADH → alcohol + CO2 + NAD+
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Fermentation
Lactic Acid Fermentation
In many cells (of bacteria, plants and most animals), pyruvic acid that accumulates as a result of glycolysis can be converted to lactic acid.
The equation for lactic acid fermentation after glycolysis is:
pyruvic acid + NADH → lactic acid + NAD+
Sometimes happens in your muscles (burning or cramps) from exercise.
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Fermentation
The first part of the equation is glycolysis. The second part shows the conversion of pyruvic acid to lactic acid.
Lactic acid fermentation converts glucose into lactic acid. The first part of the equation is glycolysis. The second part shows the conversion of pyruvic acid to lactic acid.
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24. Fermentation is used in food & beverage production.
Uses
Fermentation is used in food & beverage production.
Yogurt
Cheese
Bread
Beer and wine

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9-1
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9-1
The raw materials required for cellular respiration are
carbon dioxide and oxygen.
glucose and water.
glucose and oxygen.
carbon dioxide and water.
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9-1
Glycolysis occurs in the
mitochondria.
cytoplasm.
nucleus.
chloroplasts.
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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
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Fermentation releases energy from food molecules in the absence of
oxygen.
glucose.
NADH.
alcohol.
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9-1
The first step in fermentation is always
lactic acid production.
the Krebs cycle.
glycolysis.
alcohol production.
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31. END OF SECTION