1. Cellular Respiration & Fermentation
4.4, 4.5, & 4.6

2. 4.4 – Overview of Cellular Respiration
Key Concept:
The overall process of cellular respiration converts sugar into ATP using oxygen.
4.5 – Cellular Respiration in Detail
Key Concept:
Cellular respiration is an aerobic process with two main stages.

3. Purpose of Cellular Respiration
To make ATP from the energy stored in glucose
Glucose comes from an organism doing photosynthesis themselves or from eating foods containing glucose
Remember: the purpose of photosynthesis was just to get glucose

4. Cellular Respiration has 2 parts
Anaerobic (does not require oxygen)
Glycolysis
Aerobic (requires oxygen)
Kreb’s Cycle (Citric acid Cycle)
Electron Transport Chain (ETC)

5. Glycolysis
Takes place in cytoplasm (eukaryotes and prokaryotes do this step since all cells have cytoplasm)
Splits one glucose molecule into two pyruvate molecules
Costs the cell 2 ATP molecules to do this
4 ATP molecules are produced (only gain 2 ATP)
2 NADH molecules are formed

6. Kreb’s Cycle (Citric Acid Cycle)
Takes place in matrix of mitochondria (only in eukaryotes)
2 pyruvate (made during glycolysis) enter the mitochondrion
Each pyruvate is broken down to create 1 ATP, 3 CO2, NADH, & FADH2
Total products of Kreb’s cycle (because of 2 pyruvates):
2 ATP
6 CO2
NADH
FADH2
Will carry energy to the next step

7. Electron Transport Chain (ETC)
Takes place in inner membrane of mitochondria (cristae)
Folded to create more surface area for reactions to produce more ATP in a small space
NADH & FADH2 (from Kreb’s) donate their energy (electrons) to the electron transport chain
Oxygen is the final electron acceptor and it picks up hydrogen ions
Oxygen and hydrogen ions combine to form water (released as a waste product)
32 ATP are made

9. ATP from Cellular Respiration
4 from Glycolysis (uses up 2, so really only gain 2 ATP)
2 ATP from Kreb’s cycle
32 ATP from ETC
GAIN 36 ATP from one glucose molecule

10. Equation for Cellular Respiration
C6H12O6 + 6O2 6CO2 + 6H2O + 36ATP  Like the reverse of photosynthesis

11. What happens when there’s no/not enough oxygen or there are no mitochondria?
Answer: Fermentation
Two Kinds:
Lactic Acid Fermentation
Alcoholic Fermentation

12. Allows glycolysis to continue making ATP without oxygen

13. Lactic Acid Fermentation
Anaerobic
Occurs in muscle cells
Produces burning feeling in muscles
Occurs when body is worked to the point that more oxygen is being used than what is being taken in
This is why you breathe harder when you’re exercising is to get more oxygen to keep making ATP
Produces Lactic Acid and 2 (net) ATP

14. Alcoholic Fermentation
Anaerobic
Occurs in some bacteria and yeast
Produces CO2, ethyl alcohol, and 2 (net) ATP
Used in food production (bake bread and make wine)