1. Photosynthesis Wrap-up Onto Cellular Respiration!
Today:
Photosynthesis Wrap-up
Onto Cellular Respiration!

2. How did we do with our questions?
Are there different types of photosynthesis?
Is it possible at night?
Do other organisms besides plants do PS?
What’s the best light for PS?
How is it regulated?
What types of sugars are formed?
Do all plants photosynthesize?

3. Onto Respiration: Note that Energy Flow is Directional, but Matter is Cycled

4. Cellular Respiration What form of Energy?? Enzyme –Mediated Catabolic
Yields Energy!
Organic Compounds
Carbon Dioxide
+ Oxygen
+ Water
+ Energy!
What form of Energy??

5. ATP!

6. Cellular RESPIRATION: An Overview

7. Requires an input of energy!
Step 1: Glycolysis
Requires an input of energy!
In the cytosol…
1. Glucose (6C) is split into 2, 3-Carbon Sugars
2. These 2, 3-Carbon sugars are then oxidized two form 2 molecules of pyruvate
Releases Energy!

8. Step 1: Glycolysis

9. Step 2: The Citric Acid Cycle

10. Step 2: The Citric Acid Cycle

11. The Citric Acid Cycle Each Turn: Two carbons enter as acetate
Two completely oxidized carbons leave (CO2)
For each acetate, 3 molecules of NADH, 1 FADH2, and 1 ATP

12. The Citric Acid (Kreb’s) Cycle: A Friendlier View
German scientist Hans Krebs deciphers the Krebs Cycle in 1957.

13. All ATP Generated by Glycolysis and the Citric Acid Cycle is through Substrate-level Phosphorylation

14. Step 3: Oxidative Phosphorylation
So far, only 4 molecules of ATP from each Glucose
Where’s the rest of the energy??
How can we capture it??

15. Reviewing Electron Transport Chains

16. The Electron Transport Chain in the Inner Mitochondrial Membrane

17. This exergonic flow of electrons pumps H+ into the intermembrane space, creating a concentration gradient

18. ATP Synthase Generates ATP (Oxidative Phosphorylation!)

19. Energetic Summary of Cellular Respiration:
Efficiency = ~40%

20. Can we generate ATP under anaerobic conditions?? How??
Aerobic = oxygen present
Anaerobic = without oxygen

21. Can this proceed indefinitely? Why or why not?
Glycolysis!
Can this proceed indefinitely? Why or why not?

22. Anaerobic Respiration: Alcohol Fermentation

23. Anaerobic Respiration: Lactic Acid Fermentation

24. Anaerobic Respiration
Cellular Respiration usually requires OXYGEN as the final electron acceptor. But ANAEROBIC respiration can occur with an alternate electron acceptor.
You Try:
Diagram the process of cellular respiration.
Use your diagram to trace the movement of a single electron through this process!

25. Evolutionary Implications
Why do we think RUBISCO is sloppy?
What does this suggest about the earliest mechanisms for generating ATP??

26. The Fluid Nature of Catabolic Pathways

27. Do you want to regulate cellular respiration?
When? Where? How? Why?

28. Regulating Respiration
Phosphofructokinase is an allosteric enzyme inhibited by ATP and stimulated by AMP. It also may be inhibited by citrate from the Citric Acid Cycle.

29. Applying Your Understanding of Photosynthesis and Respiration
Am I a carbon source or sink??
What does it mean to be a carbon source?
What does it mean to be a carbon sink?

30. The Biology of the Carbon Cycle

31. More Applications…
The fat-soluble compound 2, 4-dinitrophenol (DNP, shown above) acts as a proton ionophore. In this role, it can bind protons on one side of a membrane and drift through the membrane, effectively transporting protons across a membrane. The probability of this happening is greatest on the side of the membrane with the highest concentration of protons.

32. More Applications…
Based on this information, what effect do you think DNP would have on mitochondrial function? Use your drawing of cellular respiration to explain this effect! What short –term and long-term effects do you think exposure to DNP would have on a human? Explain!