1. Cellular Respiration: Harvesting Chemical Energy Figures 6.1 – 6.5
CHAPTER 6
Cellular Respiration: Harvesting Chemical Energy
Figures 6.1 – 6.5

2. Bacteria are used to produce yogurt, sour cream, pepperoni, and cheese
Both carbon monoxide and cyanide kill by disrupting cellular respiration

3. All the energy in all the food you eat can be traced back to sunlight
If you exercise too hard, your muscles shut down from a lack of oxygen

4. BIOLOGY AND SOCIETY: FEELING THE “BURN”
When you exercise
Muscles need energy in order to perform work
Your cells use oxygen to release energy from the sugar glucose

5. Aerobic metabolism Anaerobic 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

6. 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

7. 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

8. 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

9. 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

10. Autotrophs Heterotrophs “Self-feeders”
Plants and other organisms that make all their own organic matter from inorganic nutrients
Heterotrophs
“Other-feeders”
Humans and other animals that cannot make organic molecules from inorganic ones

11. Producers
Biologists refer to plants and other autotrophs as the producers in an ecosystem
Consumers
Heterotrophs are consumers, because they eat plants or other animals
Figure 6.2

12. Chemical Cycling Between Photosynthesis and Cellular Respiration
The ingredients for photosynthesis are carbon dioxide and water
CO2 is obtained from the air by a plant’s leaves
H2O is obtained from the damp soil by a plant’s roots
Chloroplasts rearrange the atoms of these ingredients to produce sugars (glucose) and other organic molecules
Oxygen gas is a by-product of photosynthesis

13. Both plants and animals perform cellular respiration
Cellular respiration is a chemical process that harvests energy from organic molecules
Cellular respiration occurs in mitochondria
The waste products of cellular respiration, CO2 and H2O, are used in photosynthesis

14. Sunlight
energy
Ecosystem
Photosynthesis
(in chloroplasts)
Glucose
Carbon dioxide
Oxygen
Water
Cellular respiration
(in mitochondria)
for cellular work
Heat energy
Figure 6.3

15. CELLULAR RESPIRATION: AEROBIC HARVEST OF FOOD ENERGY
The main way that chemical energy is harvested from food and converted to ATP
This is an aerobic process—it requires oxygen

16. 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

17. Breathing Lungs Muscle cells Cellular respiration
Figure 6.4

18. 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
Energy
Unnumbered Figure 6.1

19. The Role of Oxygen in Cellular Respiration
During cellular respiration, hydrogen and its bonding electrons change partners
Hydrogen and its electrons go from sugar to oxygen, forming water

20. Redox Reactions
Chemical reactions that transfer electrons from one substance to another are called oxidation-reduction reactions
Redox reactions for short

21. The loss of electrons during a redox reaction is called oxidation
The acceptance of electrons during a redox reaction is called reduction

22. [Glucose loses electrons (and hydrogens)]
Oxidation
[Glucose loses electrons (and hydrogens)]
Glucose
Oxygen
Carbon
dioxide
Water
Reduction
[Oxygen gains electrons (and hydrogens)]
Unnumbered Figure 6.2

23. Why does electron transfer to oxygen release energy?
When electrons move from glucose to oxygen, it is as though they were falling
This “fall” of electrons releases energy during cellular respiration
Release
of heat
energy
Figure 6.5