1. Cellular Respiration: 9-1 Chemical Pathways
Photo Credit: Duomo Photography, Inc.

2. Chemical Energy and Food
Food serves as a source of raw materials for the cells in the body and as a source of energy.
Animal Cells
Animal
Plant
Mitochondrion
Photo Credits: left: ©Bob Gurr/DRK Photo; middle bottom: ©John Durham/Science Photo Library/Photo Researchers, Inc. ; middle top: ©Ron Boardman/Stone; right: ©Keith Porter/Photo Researchers, Inc.
Plant Cells

3. Chemical Energy and Food
One gram of the sugar glucose (C6H12O6), when burned in the presence of oxygen, releases 3811 calories (3.8 Calories) of heat energy.
A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.
The Calorie (capital “C”) used on food labels is a kilocalorie or 1000 calories.

4. Chemical Energy and Food
Cells don't “burn” glucose. Instead, they gradually release the energy from glucose and other food compounds through a process called: Cellular Respiration:
Glycolysis
Krebs cycle
Electron Transport Chain (ETC)

5. Overview of Cellular Respiration
If oxygen is present (aerobic), glycolysis is followed by…
the Krebs cycle and the electron transport chain.

6. Overview of Cellular Respiration
Electrons carried in NADH
Electrons carried
in NADH and
FADH2
Pyruvic acid
Glucose
Glycolysis
Cytoplasm
Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place inside the mitochondria.
Mitochondrion

7. Cellular Respiration What is Cellular Respiration?
Process that releases energy
by breaking down glucose
and other food molecules
in the presence of oxygen

8. Cellular Respiration The equation for cellular respiration is:
6O2 + C6H12O6 → 6CO2 + 6H2O + ATP
oxygen + glucose → carbon dioxide + water + Energy

9. Cellular Respiration
Each of the three stages of cellular respiration captures some of the chemical energy available in food molecules and uses it to produce ATP.

10. Where does each reaction take place?
Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place in the mitochondria.
Glycolysis
Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place inside the mitochondria.
Cytoplasm
Mitochondria

11. The Totals: + 1 GLUCOSE: Glycolysis: 6 ATP Krebs, ETC: 30 ATP
_______________
Total: 36 ATP

12. Review Questions Name the 3 steps of cellular respiration.
What is the overall function of respiration?
Where does glycolysis take place in the cell?
Where do Krebs and ETC take place in the cell?
Name the reactants of respiration.
Name the products of respiration.
Glycolysis, Krebs, ETC
Provide energy in form of ATP (and electron carrying molecules)
Cytoplasm
Mitochondria
Oxygen, glucose
CO2 Water Energy