2. Food serves as a source of raw
materials for the cells in the body and
as a source of energy.
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Animal
Plant
Animal Cells
Plant Cells
Mitochondrion
3. Both plant and animal cells carry out
cellular respiration in the
mitochondria.
Outer membrane Intermembrane
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Animal Cells
Plant Cells
Mitochondrion
space
Inner
membrane
Matrix
4.
5. 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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6. Cells don't “burn” glucose. Instead,
they gradually release the energy from
glucose and other food compounds.
This process begins with a pathway
called glycolysis.
Glycolysis releases a small amount of
energy.
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7. Overview of Cellular
Respiration
If oxygen is present, glycolysis is
followed by the Krebs cycle and the
electron transport chain.
Glycolysis, the Krebs cycle, and
the electron transport chain
make up a process called
cellular respiration.
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8. Overview of Cellular Respiration
Electrons carried in NADH
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Cytoplasm
Pyruvic
acid
Electrons carried
in NADH and
FADH2
Mitochondrion
Glucose Glycolysis
9. 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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10. The equation for cellular respiration is:
6O2 + C6H12O6 → 6CO2 + 6H2O + Energy
oxygen glucose carbon water energy
dioxide
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11. Each of the three stages of cellular
respiration captures some of the
chemical energy available in food
molecules and uses it to produce ATP.
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12. Glycolysis takes place in the
cytoplasm. The Krebs cycle and
electron transport take place in the
mitochondria.
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Cytoplasm
Mitochondrion
Glycolysis
13. In glycolysis, one molecule of
glucose is broken in half, producing
two molecules of pyruvic acid.
2 ADP 4 ADP 4 ATP
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2 Pyruvic
acid
2 ATP
Glucose
14. Glycolysis requires 2 ATP to start the
reaction.
When glycolysis is complete, 4 ATP
molecules have been produced.
2 ATP 2 ADP 4 ADP 4 ATP
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Glucose
2 Pyruvic
acid
15. Glycolysis gives the cell a net
gain of 2 ATP molecules.
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4 ADP 4 ATP
Glucose
2 ATP 2 ADP
2 Pyruvic
acid
16. NADH Production
One reaction of glycolysis removes 4
high-energy electrons, passing them to
an electron carrier called NAD+.
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Glucose
2 Pyruvic
acid
2 ATP 2 ADP 4 ADP 4 ATP
2NAD+
17. Each NAD+ accepts a pair of high-energy
electrons and becomes an NADH molecule.
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Glucose
2 Pyruvic
acid
2 ATP 2 ADP 4 ADP 4 ATP
2NAD+ 2
18. The NADH molecule holds high energy
electrons until they can be transferred to
other molecules.
2 ATP 2 ADP 4 ADP 4 ATP
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2NAD+ 2 Pyruvic
acid
2
To the electron
transport chain
19. 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.
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20.
21. Glycolysis
makes
Krebs cycle and fermentation
electron transport
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With
oxygen
Without
oxygen
22. 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.
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23. During fermentation, cells convert NADH to NAD+
by passing high-energy electrons back to pyruvic
acid.
This action converts NADH back into NAD+, and
allows glycolysis to continue producing a steady
supply of ATP.
Fermentation does not require
oxygen—it is an anaerobic process.
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24. The two main types of
fermentation are lactic acid
fermentation and alcoholic
fermentation.
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25. Yeasts use alcoholic fermentation to
get energy from pyruvic acid.
Alcoholic fermentation forms ethanol
and carbon dioxide as wastes.
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26. In lactic acid fermentation, the
pyruvic acid and NADH from
glycolysis are converted to lactic
acid.
It regenerates NAD+ so that glycolysis can
continue.
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27. The first part of the equation is glycolysis.
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28. The second part shows the conversion of
pyruvic acid to lactic acid.
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29. Energy needs are great when you exercise.
If oxygen is limited, muscle cells will produce
energy by lactic acid fermentation.
Lactic acid buildup in muscles will
cause soreness and cramps.
Proper breathing will promote
cellular respiration.
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30. 9-2 The Krebs Cycle and
Electron Transport
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31. 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.
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32. In the presence of oxygen, pyruvic
acid produced in glycolysis enters
the Krebs cycle.
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33. The Krebs Cycle
During the Krebs cycle, pyruvic
acid is broken down into carbon
dioxide in a series of energy-extracting
reactions.
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34. The Krebs Cycle
The Krebs cycle begins when
pyruvic acid produced by
glycolysis enters the
mitochondrion.
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35. The Krebs Cycle
One carbon is
removed, forming
CO2, and electrons
are removed,
changing NAD+ to
NADH.
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36. The Krebs Cycle
Coenzyme A joins
the 2-carbon
molecule, forming
acetyl-CoA.
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37. The Krebs Cycle
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Citric acid
Acetyl-CoA then
adds the 2-
carbon acetyl
group to a 4-
carbon
compound,
forming citric
acid.
38. Citric acid is broken down into a 5-
carbon compound, then into a 4-carbon
compound.
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39. Two more molecules of CO2 are released
and electrons join NAD+ and FAD, forming
NADH and FADH2
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40. The Krebs Cycle
In addition, one molecule of ATP is
generated.
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41.
42. The Krebs Cycle
The energy tally from 1 molecule
of pyruvic acid is
• 4 NADH- electron carrier
• 1 FADH2- electron carrier
• 1 ATP- energy carrier
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43. The Krebs Cycle
What does the cell do with all those high-energy
electrons in carriers like NADH?
In the electron transport chain,
the high-energy electrons from
NADH and FADH2 are used to
generate huge amounts of ATP.
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44. Electron Transport
Electron Transport
The electron transport chain uses the
high-energy electrons from the Krebs
cycle to convert ADP into ATP.
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45. High-energy electrons from NADH and
FADH2 are passed along the electron
transport chain from one carrier protein
to the next.
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46. Electron Transport
At the end of the chain, an enzyme
combines these electrons with hydrogen
ions and oxygen to form water.
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47. As the final electron acceptor of the electron
transport chain, oxygen gets rid of the low-energy
electrons and hydrogen ions.
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48. When 2 high-energy electrons move down
the electron transport chain, their energy is
used to move hydrogen ions (H+) across the
membrane.
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49. During electron transport, H+ ions build
up in the intermembrane space, so it is
positively charged.
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50. The other side of the membrane, from
which those H+ ions are taken, is now
negatively charged.
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51. The inner membranes of the mitochondria
contain protein spheres called ATP
synthases.
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ATP
synthase
52. As H+ ions escape through channels into
these proteins, the ATP synthase spins.
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Channel
ATP
synthase
53. As it rotates, the enzyme grabs a low-energy
ADP, attaching a phosphate, forming high-energy
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ATP.
ATP
Channel
ATP
synthase
54. On average, each pair of high-energy
electrons that moves down the electron
transport chain provides enough energy to
produce three molecules of ATP from ADP.
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55.
56. 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.
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58. Comparing Photosynthesis and Cellular Respiration
Photosynthesis and cellular respiration are the
same chemical reaction except in opposite
directions.
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59. Comparing Photosynthesis and Cellular Respiration
Same reaction flipped over!
Photosynthesis
+ 6CO2 + 6H2O C6H12O6 + 6O2
Cellular Respiration
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
out
Energy
in
60. Photosynthesis in the chloroplast
Only plants and algae have
chloroplasts
Cellular respiration in the
mitochondria
Almost all eukaryotes have
mitochondriaC
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61. Comparing Photosynthesis and
Cellular Respiration
On a global level, photosynthesis and
cellular respiration are also opposites.
•Photosynthesis removes carbon
dioxide from the atmosphere and
cellular respiration puts it back.
•Photosynthesis releases oxygen into
the atmosphere and cellular
respiration uses that oxygen to
release energy from food.
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62. Copyright Pearson Prentice Hall
9-1
The raw materials required for cellular
respiration are
a. carbon dioxide and oxygen.
b. glucose and water.
c. glucose and oxygen.
d. carbon dioxide and water.
63. Copyright Pearson Prentice Hall
9-1
Glycolysis occurs in the
a. mitochondria.
b. cytoplasm.
c. nucleus.
d. chloroplasts.
64. Copyright Pearson Prentice Hall
9-1
The net gain of ATP molecules after glycolysis is
a. 3 ATP molecules.
b. 2 ATP molecules.
c. 3 pyruvic acid molecules.
d. 4 pyruvic acid molecules
65. Copyright Pearson Prentice Hall
9-1
Fermentation releases energy from food
molecules in the absence of
a. oxygen.
b. glucose.
c. NADH.
d. alcohol.
66. Copyright Pearson Prentice Hall
9-1
The first step in fermentation is always
a. lactic acid production.
b. the Krebs cycle.
c. glycolysis.
d. alcohol production.
67. Copyright Pearson Prentice Hall
9-2
The Krebs cycle breaks pyruvic acid down into
a. oxygen.
b. NADH.
c. carbon dioxide.
d. alcohol.
68. Copyright Pearson Prentice Hall
9-2
What role does the Krebs cycle play in the cell?
a. It breaks down glucose and releases its
stored energy.
b. It releases energy from molecules formed
during glycolysis.
c. It combines carbon dioxide and water into
high-energy molecules.
d. It breaks down ATP and NADH, releasing
stored energy.
69. Copyright Pearson Prentice Hall
9-2
In eukaryotes, the electron transport chain is
located in the
a. cell membrane.
b. inner mitochondrial membrane.
c. cytoplasm.
d. outer mitochondrial membrane.
70. Copyright Pearson Prentice Hall
9-2
To generate energy over long periods, the body
must use
a. stored ATP.
b. lactic acid fermentation.
c. cellular respiration.
d. glycolysis.
71. Copyright Pearson Prentice Hall
9-2
Which statement correctly describes
photosynthesis and cellular respiration?
a. Photosynthesis releases energy, while
cellular respiration stores energy.
b. Photosynthesis and cellular respiration use
the same raw materials.
c. Cellular respiration releases energy, while
photosynthesis stores energy.
d. Cellular respiration and photosynthesis
produce the same products.
