Transcript cellular respiration

Chapter 6
Cellular Respiration: Obtaining
Energy from Food
PowerPoint® Lectures for
Campbell Essential Biology, Fourth Edition
– Eric Simon, Jane Reece, and Jean Dickey
Campbell Essential Biology with Physiology, Third Edition
– Eric Simon, Jane Reece, and Jean Dickey
Lectures by Chris C. Romero, updated by Edward J. Zalisko
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Producers and Consumers
• Plants and other autotrophs (self-feeders):
– Make their own organic matter from inorganic nutrients.
Autotrophs are producers because ecosystems depend upon them for food.
• Heterotrophs (other-feeders):
– Include humans and other animals that cannot make organic molecules
from inorganic ones.
Heterotrophs are consumers because they eat plants or other animals.
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• Plant and animal cells perform cellular respiration, a chemical
process that:
– Primarily occurs in mitochondria
– Harvests energy stored in organic molecules
– Uses oxygen
– Generates ATP
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• The waste products of cellular respiration are:
– CO2 and H2O
– Used in photosynthesis
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• Animals perform only cellular respiration.
• Plants perform:
– Photosynthesis and
– Cellular respiration
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Sunlight energy
enters ecosystem
C6H12O6
Photosynthesis
CO2
Glucose
Carbon dioxide
O2
Oxygen
H2O
Water
Cellular respiration
ATP drives cellular work
Heat energy exits ecosystem
Figure 6.2
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
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• 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.
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Oxidation
Glucose loses electrons
(and hydrogens)
C6H12O6
Glucose
 6
O2
Oxygen
6
CO2
Carbon
dioxide
 6
H 2O
Water
Reduction
Oxygen gains electrons (and hydrogens)
Figure 6.UN02
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.
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The Versatility of Cellular Respiration
• In addition to glucose, cellular respiration can “burn”:
– Diverse types of carbohydrates
– Fats
– Proteins
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Food
Polysaccharides
Sugars
Fats
Glycerol Fatty acids
Glycolysis
Acetyl
CoA
Proteins
Amino acids
Citric
Acid
Cycle
Electron
Transport
ATP
Figure 6.12
38 ATP WITH
OXYGEN
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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.
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• Glycolysis during Anaerobic conditions:
– Does not require oxygen
– Produces 2ATP molecules for each glucose broken down to
pyruvic acid
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INPUT
2 ADP
2 P
OUTPUT
2 ATP
Glycolysis
2 NAD 2 NADH
Glucose
2 NADH 2 NAD
2 Pyruvic
 2 H
acid
2 Lactic acid
Figure 6.14
The Process of Science:
Does Lactic Acid Buildup Cause Muscle Burn?
• 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.
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Battery
Battery
Force
measured
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
• 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.
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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
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• 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
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INPUT
2 ADP
2 P
OUTPUT
2 ATP
2 CO2 released
Glycolysis
2 NAD 2 NADH
Glucose
2 NADH 2 NAD
2 Pyruvic
 2 H
acid
2 Ethyl alcohol
Bread with air
bubbles produced
by fermenting yeast
Beer
fermentation
Figure 6.16