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Chapter 6
• Cellular Respiration
FEELING THE ―BURN‖
• When you exercise
– Muscles need energy in order to perform work
• Enzymes in muscle cells help a cell use glucose and
oxygen to produce ATP
• Aerobic metabolism
– When enough oxygen reaches cells to support
energy needs
• Anaerobic metabolism
– When the demand for oxygen outstrips the
body’s ability to deliver it
• Anaerobic metabolism
– Without enough oxygen, muscle cells break
down glucose to produce lactic acid
– Lactic acid is associated with the ―burn‖
associated with heavy exercise
– If too much lactic acid builds up, your muscles
give out
• Physical conditioning
allows your body to
adapt to increased
activity
– The body can increase
its ability to deliver
oxygen to muscles
• Long-distance runners
wait until the final
sprint to exceed their
aerobic capacity
Figure 6.1
ENERGY FLOW AND CHEMICAL CYCLING
IN THE BIOSPHERE
• Fuel molecules in food represent solar
energy
– Energy stored in food can be traced back to the
sun
• Animals depend on plants to convert solar
energy to chemical energy
– This chemical energy is in the form of sugars
and other organic molecules
Producers and Consumers
• Photosynthesis
– Light energy from the sun powers
a chemical process that makes
organic molecules
– This process occurs in the leaves
of terrestrial plants
• Leaves are green because they
contain chlorophyll, the pigment in
chloroplasts
• Chloroplasts are the organelles that
house the equipment for
photosynthesis
• Autotrophs
– ―Self-feeders‖
– Plants and other organisms that make all their
own organic matter from inorganic nutrients (can
make own food)
• Heterotrophs
– ―Other-feeders‖
– Humans and other animals that cannot make
organic molecules from inorganic ones (have to
eat other organisms)
• Producers
– Plants and other
autotrophic organisms
because they produce
food for consumers
• Consumers
– Heterotrophs are
consumers, because
they eat plants or
other animals
Figure 6.2
Chemical Cycling Between Photosynthesis
and Cellular Respiration
• The ingredients for photosynthesis are carbon
dioxide and water
– CO2 is obtained from the air by pores on a
plant’s leaves
– H2O is absorbed from the damp soil by the roots
– Veins transport the water from roots to leaves
• Chloroplasts rearrange the atoms of these
ingredients to produce sugars (glucose) and
other organic molecules (key products =
glucose and oxygen)
– Oxygen gas is a by-product of photosynthesis
• Both plants and animals perform cellular
respiration
– Plants use cellular respiration to harvest
energy that is stored in sugars and other
organic molecules:
– Uses oxygen and produces ATP
– Cellular respiration is a chemical process that
harvests energy from organic molecules
– Cellular respiration occurs primarily in
mitochondria
• The waste products of cellular respiration,
CO2 and H2O, are used in photosynthesis
Sunlight
energy
Ecosystem
Photosynthesis
(in chloroplasts)
Glucose
Oxygen
Carbon dioxide
Water
Cellular respiration
(in mitochondria)
for cellular work
Heat energy
Figure 6.3
CELLULAR RESPIRATION: AEROBIC
HARVEST OF FOOD ENERGY
• Cellular respiration
– The main way that chemical energy is harvested
from food and converted to ATP
– This is an aerobic process—it requires oxygen
The Relationship Between Cellular
Respiration and Breathing
• Cellular respiration and breathing are closely
related
– Cellular respiration requires a cell to exchange
gases with its surroundings
– Breathing exchanges these gases between the
blood and outside air
Breathing
Lungs
Muscle
cells
Cellular
respiration
Figure 6.4
The Overall Equation for Cellular
Respiration
• A common fuel molecule for cellular
respiration is glucose
– This is the overall equation for what happens to
glucose during cellular respiration
Glucose
Oxygen
Carbon
dioxide
Water
Cellular respiration can produce up to 38 ATP
molecules for each glucose molecule consumed
Energy
Unnumbered Figure 6.1
A Road Map for Cellular Respiration
Cytosol
Mitochondrion
High-energy
electrons
carried
mainly by
NADH
High-energy
electrons
carried
by NADH
Glycolysis
Glucose
2
Pyruvic
acid
Krebs
Cycle
Electron
Transport
Figure 6.7
• Glycolysis makes some ATP directly when
enzymes transfer phosphate groups from
fuel molecules to ADP
Enzyme
Figure 6.9
SUMMARY OF KEY CONCEPTS
• Chemical Cycling Between Photosynthesis
and Cellular Respiration
Heat
Sunlight
Photosynthesis
Cellular
respiration
Visual Summary 6.1
• The Overall Equation for Cellular
Respiration
Oxidation:
Glucose loses electrons
(and hydrogens)
Glucose
Carbon dioxide
Electrons
(and hydrogens)
Oxygen
Energy
Reduction:
Oxygen gains
electrons (and
hydrogens)
Visual Summary 6.2
• The Metabolic Pathway of Cellular
Respiration
Glucose
Oxygen
Water
Energy
Visual Summary 6.3
Today:
• Bookwork and Reading due Friday
• Prepare for Yeast Lab
– Look at the Rubric!
– Graded on Design
– Graded on Conclusion Evaluation
– Today, set up
• Variables, Hypothesis, question
• Method
• Make data table