1. Kreb’s Cycle and ETC

2. Oxygen is Present
If oxygen is present at the end of glycolysis, pyruvic acid enters the aerobic pathway. The acid changes to become Acetyl-CoA.
Here it will enter the Krebs Cycle (Citric Acid Cycle)
During the Krebs Cycle, Acetyl-CoA undergoes a series of reactions that further break it down and make energy ( 2 ATP)

4. Krebs Cycle
Pyruvic Acid undergoes a few reactions before it enters the Krebs cycle.
It becomes a molecule called Acetyl-CoA
Acetyl-CoA enters the cycle
This takes place in the mitochondria

5. Krebs Cycle (Cont.)
Acetyl-CoA is broken down into ATP and Carbon Dioxide.
Each Acetyl-CoA molecule goes through the cycle twice in order to make two ATP molecules.
Carbon Dioxide is given off as waste

7. Electron Transport Chain
Further inside the mitochondria, the last stage of respiration takes place.
Here the cell makes 32 ATP!!!
Energized electrons get passed down a chain of proteins. They give off energy at each protein(ATP)

9. ETC (Cont.) The last stop in the chain is an oxygen molecule.
The cycle stops when oxygen combines with 2 hydrogen to make the last waste product….
WATER!!!

10. Summary During Respiration we make : 1. Glycolysis – 4 ATP
2. Krebs Cycle ATP
3. Electron Transport Chain ATP
4. Total ATP!

11. Glucose
Glycolysis
Yes Oxygen
No Oxygen
Yeast
Human
____ ATP
____ as waste
Kreb’s Cycle
____ ATP
____ Final Electron Acceptor
Fermentation
Electron Transport Chain