1. Cellular Respiration and Fermentation

2. Review
The purpose of photosynthesis is to take kinetic light energy and convert it into potential chemical energy in the form of GLUCOSE
In order to build glucose, low energy CO2 and H20 molecules are built up using light energy.

3. Chloroplasts  fix carbon which requires energy input
Mitochondria  release energy from organic molecules

4. Cellular Respiration
 Goal – To BREAK DOWN glucose and use energy to produce ATP
Can happen WITH oxygen present  Aerobic 
Can happen WITHOUT oxygen present  Anaerobic

5. Two Routes an organism can release energy
Fermentation (aka anaerobic respiration)
Takes place entirely in the cytoplasm (no mitochondria necessary)
Only nets 2 ATP (inefficient) per glucose
No oxygen necessary!
Aerobic Cellular Respiration
Takes place mostly in mitochondria
Nets 36 ATP per glucose
Oxygen necessary!
Either way, both start with the same process, Glycolysis, which means “glucose splitting”

6. Overview of Cell Respiration and Fermentation
Glucose
Krebs cycle
Electron transport
Glycolysis
Alcohol or lactic acid
Fermentation (without oxygen)
IT ALL STARTS WITH GLYCOLYSIS!!!!

7. To the electron transport chain
Glycolysis
Glucose
To the electron transport chain

8. Glycolysis Summary
One molecule of glucose split in half  two molecules of pyruvic acid
Uses 2 ATP to start the process but gets 4 ATP back in the end. (Net 2 ATP!)
4 high energy electrons are removed from the carbon compounds and passed to an electron carrier
2 NAD+  2 NADH
Electrons carriers will take high energy electrons to the electron transport chain for later use!

9. What happens after glycolysis?
Depends on who you are and what your oxygen availability is.
In order to move forward with cell respiration, you must have the following;
Mitochondria
Available Oxygen
If an organism does not have one or more of these, big problem as all available NAD+ molecules will be used-up. Without available NAD+, glycolysis shuts down and now not even 2 ATP generated from glucose via glycolysis
Enter fermentation AKA anaerobic respiration.

10. Fermentation
Release of energy from food molecules in the absence of oxygen
AKA: Anaerobic respiration
Two forms:
Alcoholic fermentation
Lactic acid fermentation
NADH reverts back to NAD+ in both types by dropping back off their electrons and H ions.
With NAD+ freed up again, ATP production can continue via glycolysis

11. Lactic Acid Fermentation
Occurs in many cells
Both eukaryotic and prokaryotic
Pyruvic acid + NADH  lactic acid + NAD+
In foods, production of acid results in characteristic flavors of cheeses and yogurt
This is what happens in our muscles when we exercise heavily “feel the burn”

12. Lactic Acid Fermentation
Point of this happening is so the NADH can go back to NAD+ and keep glycolysis going!
Glucose
Pyruvic acid
Lactic acid

13. Alcoholic Fermentation
Occurs in yeast and a few other microorganisms
Pyruvic acid + NADH  alcohol + CO2 + NAD+
Bread dough rising
Wine and Beer fermentation

14. Alcohol Fermentation
(same as pyruvate)

15. Uses – producing alcohol

16. Uses – producing CO2 Bubbles

17. 3 Possible Pathways
Fermentation
Aerobic Cellular
Respiration

18. Aerobic Cellular Respiration
THE PROCESS BY WHICH CELLS UTILIZE OXYGEN TO BREAK DOWN ORGANIC MOLECULES INTO WASTE PRODUCTS, WITH THE RELEASE OF ENERGY THAT CAN BE USED FOR BIOLOGICAL WORK.
Using energy from glucose into ATP!
Equation
6O2 + C6H1206  6CO2 + 6H20 + Energy (ATP)

19. Cellular Respiration - 3 Main Steps
1.Glycolysis (same process as in fermentation)
Occurs in cytoplasm of cell
Net 2 ATP per glucose
2. Krebs Cycle
Occurs in mitochondria
3. Electron Transport Chain
Net 32 ATP per glucose

20. Electron Transport Chain
Cellular Respiration
Glucose (C6H1206) +
Oxygen (02)
Glycolysis
Krebs Cycle
Electron Transport Chain
Carbon
Dioxide
(CO2) +
Water
(H2O)

21. Electron Transport Chain
Cellular Respiration
Electrons carried in NADH
Electrons carried in NADH and FADH2
Pyruvic acid
Glucose
Electron Transport Chain
Krebs Cycle
Glycolysis
Mitochondrion
Cytoplasm

22. Overview of Aerobic Respiration2 2 32
Glucose
Glycolysis
Acetyl
CoA
Krebs cycle
Electron transport
6 NADH
2 FADH2
2 NADH
2 NADH
Alcohol or lactic acid
Fermentation (without oxygen)

23. After Glycolysis…….
With free 02 and mitochondria, a cell can release even more energy from pyruvic acid.
Only 10% of total energy of glucose released in glycolysis!
We already know how glycolysis “splits” a glucose molecule into 2 pyruvic acid, so lets pick up with what happens AFTER glycolysis

24. Structure of the Mitochondria
Outer membrane
Inner membrane
Inter-membrane space
Cristae
Projections of the inner membrane
Contain the enzymes of the ETS, ATP synthase
Matrix
Inside area of the mitochondria
Cells can contain 10 – 1000s of Mitochondria

25. Kreb’s Cycle Big Picture
Further break-down of pyruvic acid molecules into CO2 via series of energy releasing reactions.
Energy which is released is used to generate ATP (one per pyruvic acid molecule)
Electrons released during cycles used to make;
NAD+  NADH
FAD  FADH2
Will be used later in electron transport (check to be cashed!)

26. Before Pyruvic Acid enters the Kreb’s cycle, it get modified;
Carbon removed  C02
Electrons removed  NADH
Coenzyme A joins the remaining 2-carbon molecule  acetyl-CoA
Acetyl-CoA joins up with a 4-carbon compound already in the cycle and forms………… Citric Acid (6 carbon molecule)!
Equation:
Pyruvic acid  Acetyl Co A + CO2 + NADH
Entry into Krebs Cycle
Acetyl CoA + 4-C (oxaloacetate)  Citric Acid (6-C)

27. Kreb’s Cycle (aka Citric Acid Cycle
Citric Acid Production
Mitochondrion
IMPORTANT!
This cycle is repeated twice for each glucose molecule!

28. Results of Krebs Cycle Per Glucose molecule (2 cycles) 2 ATP
6 NADH  To electron transport chain
2 FADH2  To electron transport chain
6 CO2 (waste product) (4 in Krebs 2 in shuttle step)
Also, 2 NADH were generated just before Kreb’s Cyles started when pyruvic acid was converted to Acetyl-CoA!

29. Electron Transport Big Idea
All those high energy electrons which have been saved-up until now can be “cashed-in” for some big ATP gains!
Electron transport links the movement of these high-energy electrons with the formation of ATP!

30. Electron Transport
Electrons passes along an “electron transport chain”
Prokaryotes
Chain is a series of carrier proteins on cell membrane
Eukaryotes (one we really care about)
Chain is a series of carrier proteins located on inner membrane of mitochondria.

31. Electron Transport High Energy electrons passed along transport chain
At end of chain, electrons passed to H+ and Oxygen to form H20. Oxygen is final electron acceptor
Oxygen is important for the main reason that it accepts the low energy electrons and hydrogen ions which are wastes of cellular respiration!

32. Electron Transport and ATP production
The movement of electrons down transport chain is coupled to the movement of hydrogen ions across inner membrane into the intermembrane space
Hydrogen ion gradient established
Special transport proteins along inner membrane called ATP synthases.
As hydrogen moves through ATP synthase, ADP and P joined to form ATP!
CALLED CHEMIOSMOSIS

33. Electron Transport Chain
Hydrogen Ion Movement
Channel
ATP synthase
ATP Production

34. The importance of oxygen
Must be present to accept electrons and protons of hydrogen. Becomes WATER!
Krebs and ETS cannot function without O2
Photosynthesis and respiration
Products of Photosynth. are the raw materials for cellular respiration and vice versa
Both utilize ETS
Krebs and Calvin are similar, both involve rearrangements of carbon compounds
Krebs forms ATP, NADH and FADH2 while Calvin uses ATP and NADPH

35. Grand Totals  Net 36 ATP per glucose
38% efficiency
Exceeds efficiency of gas combustion in a car.

36. Totals: Step ATP NADH FADH2 Total ATP (net) Glycolysis 2 (net) 2* 66
Prep Step 2
Krebs Cycle 24
*energy is expended to get NADH (glycolysis) to ETS
Only 2 ATP per NADH from glycolysis
3 ATP per NADH (prep and Krebs); 2 ATP per FADH2

37. Energy and Exercise Quick energy After that:
ATP contained in muscles used in a few seconds
After that:
Anaerobic (weight lifting, sprinting – high ATP demands short term)
Most ATP through lactic acid fermentation (90 seconds)
Lots of oxygen required to get rid of buildup (oxygen dept)
Sore muscles – caused by tissue damage

38. (cont.) Aerobic (jogging, light weights, - med ATP demands long term)
First use ATP/glucose in blood
Glycogen
Lasts for minutes
Body breaks down fats after that