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CELLULAR RESPIRATION:
AEROBIC HARVEST OF FOOD ENERGY
• Cellular respiration is:
– The main way that chemical energy is har...
• Cellular respiration and breathing are closely related.
– Cellular respiration requires a cell to exchange gases with it...
Breathing
Cellular
respiration
Muscle
cells
Lungs
CO2
CO2
O2
O2
Figure 6.3
Breathing
Cellular
respiration
Muscle
cells
Lungs
CO2
CO2
O2
O2
Figure 6.3a
C6H12O6 CO2
O2
H2O
Glucose Oxygen Carbon
dioxide
Water
+ 6 + 66
Reduction
Oxidation
Oxygen gains electrons (and hydrogens)...
© 2010 Pearson Education, Inc.
The Role of Oxygen in Cellular Respiration
• Cellular respiration can produce up to 38 ATP ...
© 2010 Pearson Education, Inc.
Redox Reactions
• Chemical reactions that transfer electrons from one substance to
another ...
© 2010 Pearson Education, Inc.
• The loss of electrons during a redox reaction is called oxidation.
• The acceptance of el...
© 2010 Pearson Education, Inc.
• During cellular respiration glucose is oxidized while oxygen is
reduced.
© 2010 Pearson Education, Inc.
• Why does electron transfer to oxygen release energy?
– When electrons move from glucose t...
© 2010 Pearson Education, Inc.
• Cellular respiration is:
– A controlled fall of electrons
– A stepwise cascade much like ...
© 2010 Pearson Education, Inc.
NADH and Electron Transport Chains
• The path that electrons take on their way down from gl...
© 2010 Pearson Education, Inc.
• The first step is an electron acceptor called NAD+
.
– The transfer of electrons from org...
Electrons from food
Stepwise release
of energy used
to make
Hydrogen, electrons,
and oxygen combine
to produce water
Elect...
© 2010 Pearson Education, Inc.
An Overview of Cellular Respiration
• Cellular respiration:
– Is an example of a metabolic ...
Cytoplasm
Cytoplasm
Cytoplasm
Animal cell Plant cell
Mitochondrion
Mitochondrion
High-energy
electrons
carried
by NADH
Hig...
Cytoplasm
Mitochondrion
High-energy
electrons
carried
by NADH
High-energy
electrons carried
mainly by
NADH
Citric
Acid
Cyc...
© 2010 Pearson Education, Inc.
The Three Stages of Cellular Respiration
• With the big-picture view of cellular respiratio...
© 2010 Pearson Education, Inc.
Stage 1: Glycolysis
• A six-carbon glucose molecule is split in half to form two
molecules ...
Energy investment phase
Carbon atom
Phosphate
group
High-energy
electron
Key
Glucose
2 ATP
2 ADP
INPUT OUTPUT
Figure 6.7-1
Energy investment phase
Carbon atom
Phosphate
group
High-energy
electron
Key
Glucose
2 ATP
2 ADP
INPUT OUTPUT
Energy harve...
Energy investment phase
Carbon atom
Phosphate
group
High-energy
electron
Key
Glucose
2 ATP
2 ADP
INPUT OUTPUT
Energy harve...
© 2010 Pearson Education, Inc.
• Glycolysis:
– Uses two ATP molecules per glucose to split the six-carbon glucose
– Makes ...
ADP
ATP
P
P P
Enzyme
Figure 6.8
© 2010 Pearson Education, Inc.
Stage 2: The Citric Acid Cycle
• The citric acid cycle completes the breakdown of sugar.
© 2010 Pearson Education, Inc.
• In the citric acid cycle, pyruvic acid from glycolysis is first
“prepped.”
(from glycolysis) (to citric acid cycle)
Oxidation of the fuel
generates NADH
Pyruvic acid
loses a carbon
as CO2
Acetic ac...
© 2010 Pearson Education, Inc.
• The citric acid cycle:
– Extracts the energy of sugar by breaking the acetic acid molecul...
3 NAD+
ADP + P
3 NADH
FADH2
FAD
Acetic
acid
Citric
acid
Acceptor
molecule
Citric
Acid
Cycle
ATP
2 CO2
INPUT OUTPUT
Figure ...
© 2010 Pearson Education, Inc.
Stage 3: Electron Transport
• Electron transport releases the energy your cells need to mak...
© 2010 Pearson Education, Inc.
• The molecules of the electron transport chain are built into the
inner membranes of mitoc...
© 2010 Pearson Education, Inc.
• When the hydrogen ions flow back through the membrane, they
release energy.
– The hydroge...
Space between
membranes
Inner
mitochondrial
membrane
Electron
carrier
Protein
complex
Electron
flow
Matrix Electron transp...
1
2
Space
between
membranes
Inner
mitochondrial
membrane
Electron
carrier
Protein
complex
Electron
flow
Matrix Electron tr...
© 2010 Pearson Education, Inc.
The Versatility of Cellular Respiration
• In addition to glucose, cellular respiration can ...
Food
Polysaccharides Fats Proteins
Sugars Glycerol Fatty acids Amino acids
Glycolysis Acetyl
CoA
Citric
Acid
Cycle
Electro...
© 2010 Pearson Education, Inc.
Adding Up the ATP from Cellular Respiration
• Cellular respiration can generate up to 38 mo...
Cytoplasm
Mitochondrion
NADH
Citric
Acid
Cycle
Electron
Transport
Glycolysis
Glucose
2
Pyruvic
acid
2
ATP
2
ATP
NADH
NADH
...
© 2010 Pearson Education, Inc.
FERMENTATION: ANAEROBIC HARVEST
OF FOOD ENERGY
• Some of your cells can actually work for s...
© 2010 Pearson Education, Inc.
Fermentation in Human Muscle Cells
• After functioning anaerobically for about 15 seconds:
...
© 2010 Pearson Education, Inc.
• Glycolysis:
– Does not require oxygen
– Produces two ATP molecules for each glucose broke...
© 2010 Pearson Education, Inc.
• Pyruvic acid, produced by glycolysis, is
– Reduced by NADH, producing NAD+
, which keeps ...
Glucose
2 ATP
2 NAD+
2 NADH 2 NADH 2 NAD+
+ 2
2 ADP
2 Pyruvic
acid 2 Lactic acid
Glycolysis
INPUT OUTPUT
+ 2 P
H+
Figure 6...
© 2010 Pearson Education, Inc.
• Observation: Muscles produce lactic acid under anaerobic
conditions.
• Question: Does the...
Battery
Force
measured
Battery
Force
measured
Frog muscle
stimulated by
electric current
Solution prevents
diffusion of la...
© 2010 Pearson Education, Inc.
• Results: When lactic acid could diffuse away, performance
improved greatly.
• Conclusion:...
© 2010 Pearson Education, Inc.
Fermentation in Microorganisms
• Fermentation alone is able to sustain many types of
microo...
© 2010 Pearson Education, Inc.
• Yeast are a type of microscopic fungus that:
– Use a different type of fermentation
– Pro...
Glucose
2 ATP
2 NAD+
2 NADH 2 NADH 2 NAD+
+ 2
+ 2 P
2 Pyruvic
acid 2 Ethyl alcohol
Glycolysis
INPUT OUTPUT
2 CO2 released
...
Glucose
2 ATP
2 NAD+ 2 NADH 2 NADH 2 NAD+
+ 2
2 ADP
2 Pyruvic
acid 2 Ethyl alcohol
Glycolysis
INPUT OUTPUT
2 CO2 released
...
C6H12O6 CO2
ATPO2 H2O
Glucose Oxygen Carbon
dioxide
Water Energy
+ 6 + 66 +
Figure 6.UN01
C6H12O6 CO2
O2
H2O
Glucose Oxygen Carbon
dioxide
Water
+ 6 + 66
Reduction
Oxidation
Oxygen gains electrons (and hydrogens)...
Citric
Acid
Cycle
Electron
TransportGlycolysis
ATP ATP
ATP
Figure 6.UN03
Citric
Acid
Cycle
Electron
TransportGlycolysis
ATP ATP
ATP
Figure 6.UN04
Citric
Acid
Cycle
Electron
TransportGlycolysis
ATP ATP
ATP
Figure 6.UN05
C6H12O6
CO2
H2O
ATP
O2
Heat
Photosynthesis
Sunlight
Cellular
respiration
Figure 6.UN06
C6H12O6
CO2 ATPO2 H2O+ 6 + 66 + Approx. 38
Figure 6.UN07
C6H12O6
CO2
ATP
O2
H2O
Oxidation
Glucose loses electrons
(and hydrogens)
Reduction
Oxygen gains
electrons (and
hydrogens)
...
NADH
Citric
Acid
Cycle
Electron
Transport
Glycolysis
Glucose
2
Pyruvic
acid
2
ATP
2
ATP
NADH
NADH
FADH2
2
Acetyl
CoA
About...
© 2010 Pearson Education, Inc.
Sunlight energy
enters ecosystem
Photosynthesis
Cellular respiration
C6H12O6
Glucose
O2
Oxy...
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  • Figure 6.3 How breathing is related to cellular respiration.
  • Figure 6.3a How breathing is related to cellular respiration.
  • Figure 6.UN2 Redox reaction


  • Figure 6.5 The role of oxygen in harvesting food energy.
  • Figure 6.6 A road map for cellular respiration
  • Figure 6.6a A road map for cellular respiration


  • Figure 6.7 Glycolysis (Step 1)
  • Figure 6.7 Glycolysis (Step 2)
  • Figure 6.7 Glycolysis (Step 3)
  • Figure 6.8 ATP synthesis by direct phosphate transfer
  • Student Misconceptions and Concerns
    1. Perhaps more than anywhere else in general biology, students studying aerobic metabolism fail to see the forest for the trees. Students often focus on the details of each stage of aerobic metabolism and devote little attention to the overall process and products. Consider emphasizing the products, locations, and energy yields associated with glycolysis, the citric acid cycle, and electron transport before detailing the specifics of each reaction.
    2. Students often fail to realize that aerobic metabolism is a process generally similar to the burning of wood in a fireplace or campfire. Pointing out the general similarities can help students comprehend the overall reaction and heat generation associated with both processes.
    3. The advantage of the gradual degradation of glucose may not be obvious to some students. Many analogies exist that reveal the advantages of short and steady steps. Fuel in an automobile is burned slowly to best utilize the energy released from the fuel. A few fireplace logs release gradual heat to keep a room temperature steady. In both situations, excessive use of fuel becomes wasteful, reducing the efficiencies of the systems.
    Teaching Tips
    1. During cellular respiration, our cells convert about 40% of our food energy to useful work. The other 60% of the energy is released as heat. We use this heat to maintain a relatively steady body temperature near 37°C (98–99°F). This is about the same amount of heat generated by a 100-watt incandescent light bulb. If you choose to include a discussion of heat generated by aerobic metabolism, consider the following:
    a. Ask your students why they feel warm when it is 30°C (86°F) outside if their core body temperature is 37°C (98.6°F). Shouldn’t they feel cold? The answer is, our bodies are always producing heat. At these higher temperatures, we are producing more heat than we need to maintain a body temperature around 37°C. Thus, we sweat and behave in ways that helps us get rid of the extra heat from cellular respiration.
    b. Share this calculation with your students. Depending upon the size and activity of a person, a human might burn 2,000 dietary Calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0 to 100°C. This is something to think about the next time you heat water on the stove! (Note: Consider bringing a 2-liter bottle as a visual aid, or ten 2-liter bottles to make the point above; 100 Calories raises 1 liter of water 100C; Note: it takes much more energy to melt ice or evaporate water as steam.)
    2. The location within a cell of each of the following reactions is often lost in the details of the processes. Yet, the locations are important. The Evolution Connection section at the end of this chapter discusses the significance of glycolysis occurring in the cytosol. Consider pointing to a diagram of a cell, with mitochondrial detail, as you lecture on cellular respiration to emphasize the location of each stage.
    3. As you relate the structure of the inner mitochondrial membrane to its functions, challenge the students to suggest an adaptive advantage of the many folds of this inner membrane. These folds greatly increase the membrane region available for the associated reactions.
    4. The production of NADH by glycolysis and the citric acid cycle, instead of just the direct production of ATP, can get confusing for students. Help students understand that NADH molecules have energy value, to be cashed in by the electron transport chain. The NADH can therefore be thought of as casino chips, accumulated along the way to be cashed in at the electron transport cashier.
    5. The authors developed an analogy between the function of the inner mitochondrial membrane and a dam. A reservoir of hydrogen ions is built up between the two mitochondrial membranes, like a dam holding back water. As the hydrogen ions move down their concentration gradient, they spin the ATP synthase, which helps generate ATP. In a dam, water rushing downhill turns giant turbines, which generate electricity.
    6. Students should be reminded that the ATP yield per glucose molecule of up to 38 ATP is only a potential. The complex chemistry of aerobic metabolism can only yield this amount under ideal conditions, when every substrate and enzyme is immediately available. Such circumstances may only rarely occur in a working cell.
  • Figure 6.9 The link between glycolysis and the citric acid cycle: the conversion of pyruvic acid to acetyl coA.
  • Figure 6.10 The citric acid cycle
  • Figure 6.11 How electron transport drives ATP synthase machines
  • Figure 6.11a How electron transport drives ATP synthase machines
  • Figure 6.12 Energy from food
  • Figure 6.13 A summary of ATP yield during cellular respiration
  • Figure 6.14a Fermentation: Producing lactic acid
  • Figure 6.15 A.V. Hill's apparatus for measuring muscle fatigue
  • Figure 6.16 Fermentation: Producing ethyl alcohol
  • Figure 6.16a Fermentation: Producing ethyl alcohol
  • Figure 6.UN1 Overall equation of cellular respiration
  • Figure 6.UN2 Redox reaction
  • Figure 6.UN3 Glycosis orientation diagram
  • Figure 6.UN4 Citric acid cycle orientation diagram
  • Figure 6.UN5 Electron transport orientation diagram
  • Figure 6.UN6 Summary: Chemical cycling
  • Figure 6.UN7 Summary: Overall equation for cellular respiration
  • Figure 6.UN8 Summary: Role of oxygen in cellular respiration
  • Figure 6.UN9 Summary: Metabolic pathway of cellular respiration
  • Figure 6.2 Energy flow and chemical cycling in ecosystems
  • Transcript of "bio"

    1. 1. CELLULAR RESPIRATION: AEROBIC HARVEST OF FOOD ENERGY • Cellular respiration is: – The main way that chemical energy is harvested from food and converted to ATP – An aerobic process—it requires oxygen © 2010 Pearson Education, Inc.
    2. 2. • Cellular respiration and breathing are closely related. – Cellular respiration requires a cell to exchange gases with its surroundings. – Cells take in oxygen gas. – Cells release waste carbon dioxide gas. – Breathing exchanges these same gases between the blood and outside air. © 2010 Pearson Education, Inc.
    3. 3. Breathing Cellular respiration Muscle cells Lungs CO2 CO2 O2 O2 Figure 6.3
    4. 4. Breathing Cellular respiration Muscle cells Lungs CO2 CO2 O2 O2 Figure 6.3a
    5. 5. C6H12O6 CO2 O2 H2O Glucose Oxygen Carbon dioxide Water + 6 + 66 Reduction Oxidation Oxygen gains electrons (and hydrogens) Glucose loses electrons (and hydrogens) Figure 6.UN02
    6. 6. © 2010 Pearson Education, Inc. The Role of Oxygen in Cellular Respiration • Cellular respiration can produce up to 38 ATP molecules for each glucose molecule consumed. • During cellular respiration, hydrogen and its bonding electrons change partners. – Hydrogen and its electrons go from sugar to oxygen, forming water. – This hydrogen transfer is why oxygen is so vital to cellular respiration.
    7. 7. © 2010 Pearson Education, Inc. Redox Reactions • Chemical reactions that transfer electrons from one substance to another are called: – Oxidation-reduction reactions or – Redox reactions for short
    8. 8. © 2010 Pearson Education, Inc. • The loss of electrons during a redox reaction is called oxidation. • The acceptance of electrons during a redox reaction is called reduction.
    9. 9. © 2010 Pearson Education, Inc. • During cellular respiration glucose is oxidized while oxygen is reduced.
    10. 10. © 2010 Pearson Education, Inc. • Why does electron transfer to oxygen release energy? – When electrons move from glucose to oxygen, it is as though the electrons were falling. – This “fall” of electrons releases energy during cellular respiration.
    11. 11. © 2010 Pearson Education, Inc. • Cellular respiration is: – A controlled fall of electrons – A stepwise cascade much like going down a staircase
    12. 12. © 2010 Pearson Education, Inc. NADH and Electron Transport Chains • The path that electrons take on their way down from glucose to oxygen involves many steps.
    13. 13. © 2010 Pearson Education, Inc. • The first step is an electron acceptor called NAD+ . – The transfer of electrons from organic fuel to NAD+ reduces it to NADH. • The rest of the path consists of an electron transport chain, which: – Involves a series of redox reactions – Ultimately leads to the production of large amounts of ATP
    14. 14. Electrons from food Stepwise release of energy used to make Hydrogen, electrons, and oxygen combine to produce water Electron transportchain NADHNAD+ H+ H+ ATP H2O O2 2 2 2 2 2 1 e− e− e− e− e− e− Figure 6.5
    15. 15. © 2010 Pearson Education, Inc. An Overview of Cellular Respiration • Cellular respiration: – Is an example of a metabolic pathway, which is a series of chemical reactions in cells • All of the reactions involved in cellular respiration can be grouped into three main stages: – Glycolysis – The citric acid cycle – Electron transport
    16. 16. Cytoplasm Cytoplasm Cytoplasm Animal cell Plant cell Mitochondrion Mitochondrion High-energy electrons carried by NADH High-energy electrons carried mainly by NADH Citric Acid Cycle Electron Transport Glycolysis Glucose 2 Pyruvic acid ATP ATP ATP Figure 6.6
    17. 17. Cytoplasm Mitochondrion High-energy electrons carried by NADH High-energy electrons carried mainly by NADH Citric Acid Cycle Electron Transport Glycolysis Glucose 2 Pyruvic acid ATP ATP ATP Figure 6.6a
    18. 18. © 2010 Pearson Education, Inc. The Three Stages of Cellular Respiration • With the big-picture view of cellular respiration in mind, let’s examine the process in more detail.
    19. 19. © 2010 Pearson Education, Inc. Stage 1: Glycolysis • A six-carbon glucose molecule is split in half to form two molecules of pyruvic acid. • These two molecules then donate high energy electrons to NAD+ , forming NADH.
    20. 20. Energy investment phase Carbon atom Phosphate group High-energy electron Key Glucose 2 ATP 2 ADP INPUT OUTPUT Figure 6.7-1
    21. 21. Energy investment phase Carbon atom Phosphate group High-energy electron Key Glucose 2 ATP 2 ADP INPUT OUTPUT Energy harvest phase NADH NADH NAD+ NAD+ Figure 6.7-2
    22. 22. Energy investment phase Carbon atom Phosphate group High-energy electron Key Glucose 2 ATP 2 ADP INPUT OUTPUT Energy harvest phase NADH NADH NAD+ NAD+ 2 ATP 2 ATP 2 ADP 2 ADP 2 Pyruvic acid Figure 6.7-3
    23. 23. © 2010 Pearson Education, Inc. • Glycolysis: – Uses two ATP molecules per glucose to split the six-carbon glucose – Makes four additional ATP directly when enzymes transfer phosphate groups from fuel molecules to ADP • Thus, glycolysis produces a net of two molecules of ATP per glucose molecule.
    24. 24. ADP ATP P P P Enzyme Figure 6.8
    25. 25. © 2010 Pearson Education, Inc. Stage 2: The Citric Acid Cycle • The citric acid cycle completes the breakdown of sugar.
    26. 26. © 2010 Pearson Education, Inc. • In the citric acid cycle, pyruvic acid from glycolysis is first “prepped.”
    27. 27. (from glycolysis) (to citric acid cycle) Oxidation of the fuel generates NADH Pyruvic acid loses a carbon as CO2 Acetic acid attaches to coenzyme APyruvic acid Acetic acid Acetyl CoA Coenzyme A CoA CO2 NAD+ NADH INPUT OUTPUT Figure 6.9
    28. 28. © 2010 Pearson Education, Inc. • The citric acid cycle: – Extracts the energy of sugar by breaking the acetic acid molecules all the way down to CO2 – Uses some of this energy to make ATP – Forms NADH and FADH2 Blast Animation: Harvesting Energy: Krebs Cycle
    29. 29. 3 NAD+ ADP + P 3 NADH FADH2 FAD Acetic acid Citric acid Acceptor molecule Citric Acid Cycle ATP 2 CO2 INPUT OUTPUT Figure 6.10
    30. 30. © 2010 Pearson Education, Inc. Stage 3: Electron Transport • Electron transport releases the energy your cells need to make the most of their ATP.
    31. 31. © 2010 Pearson Education, Inc. • The molecules of the electron transport chain are built into the inner membranes of mitochondria. – The chain functions as a chemical machine that uses energy released by the “fall” of electrons to pump hydrogen ions across the inner mitochondrial membrane. – These ions store potential energy.
    32. 32. © 2010 Pearson Education, Inc. • When the hydrogen ions flow back through the membrane, they release energy. – The hydrogen ions flow through ATP synthase. – ATP synthase: – Takes the energy from this flow – Synthesizes ATP
    33. 33. Space between membranes Inner mitochondrial membrane Electron carrier Protein complex Electron flow Matrix Electron transport chain ATP synthase NADH NAD+ FADH2 FAD ATPADP + H2OO2 H+ 1 2 H+H+H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+H+ H++ 2 P Figure 6.11
    34. 34. 1 2 Space between membranes Inner mitochondrial membrane Electron carrier Protein complex Electron flow Matrix Electron transport chain ATP synthase NADH NAD+ FADH2 FAD ATPADP H2OO2 H+ H+H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+H+ H++ 2 P+ Figure 6.11a
    35. 35. © 2010 Pearson Education, Inc. The Versatility of Cellular Respiration • In addition to glucose, cellular respiration can “burn”: – Diverse types of carbohydrates – Fats – Proteins
    36. 36. Food Polysaccharides Fats Proteins Sugars Glycerol Fatty acids Amino acids Glycolysis Acetyl CoA Citric Acid Cycle Electron Transport ATP Figure 6.12
    37. 37. © 2010 Pearson Education, Inc. Adding Up the ATP from Cellular Respiration • Cellular respiration can generate up to 38 molecules of ATP per molecule of glucose.
    38. 38. Cytoplasm Mitochondrion NADH Citric Acid Cycle Electron Transport Glycolysis Glucose 2 Pyruvic acid 2 ATP 2 ATP NADH NADH FADH2 Maximum per glucose: 2 Acetyl CoA About 34 ATP by direct synthesis by direct synthesis by ATP synthase 2 2 2 6 About 38 ATP Figure 6.13
    39. 39. © 2010 Pearson Education, Inc. FERMENTATION: ANAEROBIC HARVEST OF FOOD ENERGY • Some of your cells can actually work for short periods without oxygen. • Fermentation is the anaerobic (without oxygen) harvest of food energy.
    40. 40. © 2010 Pearson Education, Inc. Fermentation in Human Muscle Cells • After functioning anaerobically for about 15 seconds: – Muscle cells will begin to generate ATP by the process of fermentation • Fermentation relies on glycolysis to produce ATP.
    41. 41. © 2010 Pearson Education, Inc. • Glycolysis: – Does not require oxygen – Produces two ATP molecules for each glucose broken down to pyruvic acid
    42. 42. © 2010 Pearson Education, Inc. • Pyruvic acid, produced by glycolysis, is – Reduced by NADH, producing NAD+ , which keeps glycolysis going. • In human muscle cells, lactic acid is a by-product. Animation: Fermentation Overview
    43. 43. Glucose 2 ATP 2 NAD+ 2 NADH 2 NADH 2 NAD+ + 2 2 ADP 2 Pyruvic acid 2 Lactic acid Glycolysis INPUT OUTPUT + 2 P H+ Figure 6.14a
    44. 44. © 2010 Pearson Education, Inc. • Observation: Muscles produce lactic acid under anaerobic conditions. • Question: Does the buildup of lactic acid cause muscle fatigue? • Hypothesis: The buildup of lactic acid would cause muscle activity to stop. • Experiment: Tested frog muscles under conditions when lactic acid could and could not diffuse away. The Process of Science: Does Lactic Acid Buildup Cause Muscle Burn?
    45. 45. Battery Force measured Battery Force measured Frog muscle stimulated by electric current Solution prevents diffusion of lactic acid Solution allows diffusion of lactic acid; muscle can work for twice as long Figure 6.15
    46. 46. © 2010 Pearson Education, Inc. • Results: When lactic acid could diffuse away, performance improved greatly. • Conclusion: Lactic acid accumulation is the primary cause of failure in muscle tissue. • However, recent evidence suggests that the role of lactic acid in muscle function remains unclear.
    47. 47. © 2010 Pearson Education, Inc. Fermentation in Microorganisms • Fermentation alone is able to sustain many types of microorganisms. • The lactic acid produced by microbes using fermentation is used to produce: – Cheese, sour cream, and yogurt dairy products – Soy sauce, pickles, olives – Sausage meat products
    48. 48. © 2010 Pearson Education, Inc. • Yeast are a type of microscopic fungus that: – Use a different type of fermentation – Produce CO2 and ethyl alcohol instead of lactic acid • This type of fermentation, called alcoholic fermentation, is used to produce: – Beer – Wine – Breads
    49. 49. Glucose 2 ATP 2 NAD+ 2 NADH 2 NADH 2 NAD+ + 2 + 2 P 2 Pyruvic acid 2 Ethyl alcohol Glycolysis INPUT OUTPUT 2 CO2 released Bread with air bubbles produced by fermenting yeast Beer fermentation 2 ADP H+ Figure 6.16
    50. 50. Glucose 2 ATP 2 NAD+ 2 NADH 2 NADH 2 NAD+ + 2 2 ADP 2 Pyruvic acid 2 Ethyl alcohol Glycolysis INPUT OUTPUT 2 CO2 released + 2 P H+ Figure 6.16a
    51. 51. C6H12O6 CO2 ATPO2 H2O Glucose Oxygen Carbon dioxide Water Energy + 6 + 66 + Figure 6.UN01
    52. 52. C6H12O6 CO2 O2 H2O Glucose Oxygen Carbon dioxide Water + 6 + 66 Reduction Oxidation Oxygen gains electrons (and hydrogens) Glucose loses electrons (and hydrogens) Figure 6.UN02
    53. 53. Citric Acid Cycle Electron TransportGlycolysis ATP ATP ATP Figure 6.UN03
    54. 54. Citric Acid Cycle Electron TransportGlycolysis ATP ATP ATP Figure 6.UN04
    55. 55. Citric Acid Cycle Electron TransportGlycolysis ATP ATP ATP Figure 6.UN05
    56. 56. C6H12O6 CO2 H2O ATP O2 Heat Photosynthesis Sunlight Cellular respiration Figure 6.UN06
    57. 57. C6H12O6 CO2 ATPO2 H2O+ 6 + 66 + Approx. 38 Figure 6.UN07
    58. 58. C6H12O6 CO2 ATP O2 H2O Oxidation Glucose loses electrons (and hydrogens) Reduction Oxygen gains electrons (and hydrogens) Electrons (and hydrogens) Figure 6.UN08
    59. 59. NADH Citric Acid Cycle Electron Transport Glycolysis Glucose 2 Pyruvic acid 2 ATP 2 ATP NADH NADH FADH2 2 Acetyl CoA About 34 ATPby direct synthesis by direct synthesis by ATP synthase 2 2 2 6 About 38 ATP 2 CO2 CO2 O2 H2O 4 Mitochondrion Figure 6.UN09
    60. 60. © 2010 Pearson Education, Inc. Sunlight energy enters ecosystem Photosynthesis Cellular respiration C6H12O6 Glucose O2 Oxygen CO2 Carbon dioxide H2O Water drives cellular work Heat energy exits ecosystem ATP Figure 6.2
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