1. Respiration

2. Chemical Cycling Cellular Respiration Photosynthesis
C6H12O6+O2CO2+H2O
Photosynthesis
CO2+H2O C6H12O6+O2
Why do we need to eat food?

3. Respiration and Breathing
How does cellular respiration relate to breathing?
How exactly is O2 used in the cells?
Why exactly do we breath out CO2?

4. Cellular Reactions
What type of bond holds food molecules together?

5. Cellular Reactions What type of bond holds food molecules together?
Covalent bonds: sharing of electrons
When looking at the formulas, we are looking at the transfers of electrons

6. Redox Reactions
Chemical reactions that transfer electrons from one substance to another
Oxidation: loss of electrons from a molecule
Reduction: gain of electrons

7. Redox Reactions
When electrons change partners, from sugar to oxygen, energy is released
Why?
Because electrons are being transferred from a less stable molecule (sugar) to a more stable molecule (O2)
Remember, the less stable the molecule, the more potential energy
O2 is one of the most stable molecules and its used by cells to cause redox reactions

8. Redox Reactions
As electrons are passed from a less stable to a more stable molecule, energy is released
This energy is used to recycle ADP to ATP

9. Cells Must Be Efficient
What would happen if our cells burn glucose (releasing electrons) all at once?

10. Redox Reactions

11. One Way We Regenerate ATP

12. The Fast Way!

13. A Closer Look Cellular Respiration has three main stages
Glycolysis
Krebs Cycle
Electron Transport Chain
You need to know:
The purpose of each stage
Where it takes place

14. A Closer Look Glycolysis “sugar splitting” Glucose is split in two
Makes it easier to harvest electrons in the glucose molecule
Takes place in cytosol
Because glucose is split (less stable to more stable), a little energy is released to make ATP

16. Glycolysis Summary

17. Glycolysis  Krebs Cycle
Pyruvic Acid
Two molecules from glycolysis (cytoplasm)
Enters mitochondria
PA does not enter Krebs cycle
Two Acetyl-CoA

18. Pyruvate Processing

19. A Closer Look Krebs Cycle (Citric Acid Cycle)
Completely strips the split sugar molecules of their electrons
Electrons are carried off by NADH & FADH2
A waste product is produced (CO2)
A small amount of energy is used to make ATP
Takes place in mitochondria

21. Chemiosmosis Electron Transport Chain
Electrons captured by NADH are passed down a chain of proteins
O2 is the final electron acceptor (most stable)
Energy is released as electrons are passed down the chain to O2
This energy is used to make ATP….but how?

22. The ETC: Review

23. ATP Synthase

24. Summary

26. What If O2 is Absent? When muscles are over worked, they run out of O2
Without O2, the Krebs Cycle and ETC shut down
Glycolysis produces small amounts of energy and lactic acid (ethyl alcohol)
Lactic Acid

28. Summary We need the electrons in food to drive the synthesis of ATP
We need O2 because it’s a stable electron acceptor and therefore runs the ETC
CO2 is a waste product produced after foods have been completely stripped of their electrons (exhale out lungs)
Cellular respiration is a three stage process