1. Cellular Respiration (9.1 and 9.2)

2. Chemical Energy and Food
calorie
Measure of the energy stored in food
1 calorie is the amount of energy needed to raise the temperature of 1 gram of water by 1 °C
The Calorie = 1000 calories
There is energy in each type of macromolecule
Carbohydrates 4 calories/gram
Proteins 4 calories/gram
Lipids 9 calories/gram

3. Cells Break down food molecules gradually
Capturing a little bit of energy in key steps
Energy is stored in chemical bonds
Use the energy to make molecules such as ATP that directly power the activities of the cell

4. What is Cellular Respiration?
The process that releases energy from food in the presence of oxygen
Represented by the equation:
C6H12O6 + 6O > 6CO2 + 6H2O + ATP
glucose oxygen carbon dioxide water energy
An aerobic process because oxygen in required
A living cell has to control the release of this energy

5. Stages of Cellular Respiration
Glycolysis
Krebs cycle
Electron Transport Chain

6. 1. Glycolysis Only a small amount of energy is captured to produce
energy from glucose in this stage
90% of the available energy
locked in a molecule called
pyruvic acid
6C glucose is broken down into 2 molecules of pyruvic acid, each with 3 carbons
Produces 2 ATP molecules

7. 2. Krebs Cycle Pyruvic acid from glycolysis reacts to form
acetyl-CoA which enters
this stage of the reaction
Citric acid is produced from the reaction
A little more energy is produced
Carbon dioxide and 2 more ATP molecules are produced

8. 3. Electron Transport Chain
The most energy is
produced in this part
of the reaction
Requires reactants from the other two stages
32 ATP molecules produced along with water (H2O)

9. Energy Totals Stage of Cellular Respiration
# of ATP Molecules Produced
Glycolysis 2
Krebs Cycle
Electron Transport Chain 32
TOTAL
36 ATP Molecules

10. Oxygen and Energy
Oxygen is not required for the first stage of cellular respiration
Anaerobic – in the absence of oxygen
Glycolysis does not require oxygen
Oxygen is required for the last two stages of cellular respiration
Aerobic process – requiring oxygen
Oxygen is required for the Krebs Cycle and the electron transport chain

11. Cellular Locations Cytoplasm Site of glycolysis Mitochondria
Krebs cycle
Electron transport chain

12. Fermentation (9.3) In the absence of oxygen, fermentation releases
energy from food
molecules by producing
ATP

13. 2 Types of Fermentation Alcoholic Lactic Acid
Produces ethyl alcohol and CO2
Used in beer , wine and bread-making
Lactic Acid
Converts pyruvic acid to lactic acid
Does not give off CO2
Humans produce lactic acid during exercise
Certain prokaryotes/bacteria undergo this process
Used widely in food production: cheese, yogurt, buttermilk, sour cream, pickles, sauerkraut, kimchi

14. Energy and Exercise Only enough ATP energy in
cells for a few seconds of intense activity
After energy used up, muscle cells
produce ATP through lactic acid fermentation
Fermentation produces lactic acid
as a byproduct
Heavy breathing pays the
oxygen debt created by exercise
and rids the body of lactic acid