1. Cellular Respiration Vocabulary Glycolysis Cellular respiration
Fermentation
Anaerobic
Aerobic
ATP
Glucose

2. After glucose is made in photosynthesis, energy in the bonds of the glucose molecule are broken down to release energy.
Remember: all food we eat is eventually broken down into glucose
Occurs in two steps:
Glycolysis: Breaks down glucose
Cell respiration: Uses oxygen to finish breaking down the products from glycolysis
Cellular Respiration occurs in both plant & animal cells in the cytoplasm and the mitochondria

3. Glucose + Oxygen Carbon Dioxide + Water C6H12O6 + 6O2 6CO2 + 6H2O
Animal
GLUCOSE
CO2 O2
H2O & heat energy
cell
Glucose Oxygen Carbon Dioxide Water
C6H12O O CO2 + 6H2O
Look Familiar?

4. Chemical Energy and Food
Cells gradually release energy from food
Food (glucose), like fuel, is "burned" by our cells for energy
if it's burned all at once, too much energy is released
Therefore, the reaction is broken down into many small steps controlled by ENZYMES
Cells gradually release the energy from glucose and other compounds

5. The energy our body uses exists in the form of ATP.
ATP provides a base chemical reaction that allows all body functions to occur regularly
energy is stored in bonds between phosphate groups

6. Step 1: Glycolysis
Process of releasing energy from carbohydrates starts with gylcolysis
Glycolysis= breaking down glucose
Glucose is broken in half
Product= 2 3-carbon molecules called pyruvic acid
Takes place in the cytoplasm of a cell
NO oxygen required
Needs two ATP to get started (an “investment”)
Produces 4 ATP when done
NAD+ accepts high energy electrons from food  NADH
Electron carrier

7. After glycolysis, it all depends on oxygen
If oxygen IS present, the cell next takes a pathway called Respiration (Krebs Cycle)
If oxygen is NOT present, the cell next takes a pathway called fermentation

9. Respiration/Krebs Cycle
takes place in the Mitochondria
Only happens if oxygen is PRESENT (aerobic)
Uses the pyruvic acid from glycolysis to produce carbon dioxide, water, and 34 ATP per molecule of glucose

10. The folds of the mitochondria provide more surface area for these chemical reactions

11. The Kreb Cycle or Citric Acid Cycle can be very confusing!!
We only need to know that pyruvate goes in and C02 comes out.

12. Summary of Cellular Respiration
GLYCOLYSIS
“breaks down glucose”
RESPIRATION/ Kreb’s Cycle
Location in the cell:
Cytoplasm
Mitochondria
It starts with:
C6H12O6 (glucose)
2 pyruvic acid
It ends with:
2 (C3H6O3) pyruvic acid
H2O, CO2, ATP
Is Oxygen required? NO
YES!  AEROBIC
# of ATP’s Produced:
2 (tiny)
34 (lots!)

13. GRAND TOTAL= 36 ATP!! 2 are produced in Glycolysis
34 in Respiration/ Kreb’s Cycle
How efficient is this??
The 36 ATP molecules the cell makes per 1 glucose represents about 38% of the total energy in glucose
Even though it doesn’t seem like much, this is more efficient than your car’s gas burning engine
What happens to the remaining 62%???
It is released as heat.

14. Changes NADH back to NAD+ so glycolysis can continue
Fermentation: release of energy from food molecules in absence of oxygen (anaerobic)
Enables cells to carry out energy production in the absence of Oxygen
Fermentation occurs in many organisms:
In Humans and animals, lactic acid fermentation occurs
In yeast and other microorganisms, alcoholic fermentation occurs
Result of glycolysis + fermentation yields 2 ATP molecules per 1 molecule of glucose (not nearly as much energy!!!!)
Changes NADH back to NAD+ so glycolysis can continue

15. 2 Fermentation Pathways:
1. Lactic Acid Fermentation:
pyruvic acid from glycolysis is converted to lactic acid
lactic acid is produced in muscles during rapid exercise (body can't supply enough O2 to the tissues)
the build-up of lactic acid causes a burning, painful sensation in your muscles
Without enough oxygen, the body can’t produce all of the ATP that is required
Lactic Acid Fermentation allows the body to “catch up” from an oxygen deficit so that glycolysis/Krebs cycles can continue (producing more ATP)

16. Lactic Acid Fermentation
Without enough oxygen, the body can’t produce all of the ATP that is required
Lactic Acid Fermentation allows the body to “catch up” from an oxygen deficit so that glycolysis/Krebs cycles can continue (producing more ATP)

17. Alcoholic Fermentation:
Occurs in yeast cells & some other microorganisms
Pyruvic acid is broken down into a 2-Carbon alcohol plus carbon dioxide

19. Remember… Glycolysis can occur if oxygen is present or absent
Glycolysis is ALWAYS the first step in breaking down glucose
If oxygen IS present, then cells proceed with Respiration/Krebs
If oxygen is NOT present, then cells ferment