1. Cellular Respiration

2. What we will cover
Adenosine triphosphate ATP is the immediate source of energy for most cellular processes
ATP breaks down to ADP and releases energy
ATP is generated in the aerobic breakdown of carbohydrate
In anaerobic respiration ethanol and lactate are produced and NAD (a coenzyme) is regenerated and can be used to make ATP

3. C N
NH2 HC CH H O OH
CH2 O- P
Ribose
Phosphates
Adenine
Adenosine
Triphosphate
In cells ATP is converted to ADP; energy is released when the bond connecting the phosphates is broken.

4. ATP to ADP +Pi Releases Energy

5. Aerobic Respiration

6. There are three phases to Aerobic Respiration ... they are:
1. Glycolysis (same as the glycolysis of anaerobic respiration)
2. Krebs cycle (AKA - Citric Acid cycle)
3. Oxidative Phosphorylation and The Electron Transport Chain

7. The Separate Biochemical Steps
GLYCOLYSIS
LINK REACTION
TRICARBOXYLIC ACID OR KREBS CYCLE
ELECTRON TRANSPORT SYSTEM OR OXIDATIVE PHOSPHORYLATION

8. Phase One: Glycolysis (takes place in the cytoplasm)
Glucose (6 carbons)
Pyruvic Acid (3C)
2 ATP’s supply the activation energy
4 ATP’s are produced
2 NAD+ + 2 e NADH
4 ATP Yield = 2 ATP Net Gain

10. The First Stage of Respiration for ALL living organisms, anaerobes or aerobes, is called Glycolysis and takes place in the Cytosol.

11. Glycolysis
glyco means “glucose/sugar”, and
lysis means “to split”. Therefore,
glycolysis means “to split glucose”
This process was likely used to supply energy for the ancient forms of bacteria.

12. Glycolysis
Function - to split glucose and produce NADH, ATP and Pyruvate (pyruvic acid).
Location - Cytosol

13. Reactants for Glycolysis
Glucose
2 ATP…. As activation energy
4 ADP and 4P
Enzymes
2 NAD+ (Nicotinamide Adenine Dinucleotide, an energy carrier)

14. 2 ATP’s supply the activation energy
Glycolysis
4 ATP’s are produced
Pyruvic Acid (3 Carbons)
Glucose (6 carbons)
2 ATP’s supply the activation energy
Pyruvic Acid (3 Carbons)
2 NAD+ + 2 e NADH
4 ATP Yield = 2 ATP Net Gain

15. Products of Glycolysis
2 Pyruvic Acids (a 3C acid)
4 ATP
2 NADH

16. Net Result 2 Pyruvic Acid 2 ATP per glucose (4 – 2 = 2) 2 NADH
In summary, glycolysis takes one glucose and turns it into 2 pyruvates (molecules of pyruvic acid), 2 NADH and a net of 2 ATP.

17. Recap phase 1 - Glycolysis Phase 2 – Krebs Cycle
Cellular Respiration
Recap phase 1 - Glycolysis
Phase 2 – Krebs Cycle

18. Glycolysis
Function - Split down the glucose molecules so they are small enough to enter the Mitochondria
Products:
2 Pyruvic Acids (a 3 Carbon acid)
4 ATP
2 NADH
ATP – is the immediate source of energy for most cellular processes
NADH – carries electrons to the Electron Transport Chain

19. 2 molecules of triose phosphate
Glycolysis
1 molecule of glucose
(What you need to know) 6
2ATP
2ADP
phosphorylation
2 molecules of triose phosphate 3 3
4ADP
4ATP
2NAD
Reduced 2NAD
2 molecules of pyruvate
What is the net production of ATP? 3 3

20. The story so far

21. NADH and FADH NAD = Nicotinamide Adenine Dinucleotide
FAD = Flavin Adenine Dinucleotide
NADH and FADH are Coenzymes which carry energy in the form of electrons
NADH = reduced NAD
FADH = FADH2 = reduced FAD

22. Oxidation and Reduction
Oxidation describes the loss of electrons / hydrogen or gain of oxygen (NAD/ FAD)
Reduction describes the gain of electrons / hydrogen or a loss of oxygen. (NADH/ FADH)

23. The Link Reaction
In order for Aerobic Respiration to continue the Pyruvic acid is first converted to Acetic Acid by losing a carbon atom and 2 oxygens as CO2.
The Acetic acid then must enter the matrix region of the mitochondria. The CO2 produced is the CO2 animals exhale when they breathe.

24. Phase Two: The Krebs Cycle (AKA the Citric Acid Cycle)
Once the Acetic Acid enters the Matrix it combines with Coenzyme A to form a new molecule called Acetyl-CoA. The Acetyl-CoA then enters the Krebs Cycle.
CoA breaks off to gather more acetic acid. The Acetic acid is broken down.
Sir Hans Adolf Krebs
Produces most of the cell's energy in the form of NADH and FADH2… not ATP
Does NOT require O2

25. The Link reaction
Mitochondrion
Citric Acid Production

26. Link Reaction 3 2 pyruvate coenzyme A NAD Reduced NAD NAD Reduced NAD
Carbon
dioxide
acetyl coenzyme A 2

27. The Krebs cycle 27

28.  The Krebs Cycle
Citric Acid Production
Mitochondrion

29. Reduced co enzymes 3NADH
Krebs Cycle 2
acetyl coA
citrate
oxaloacetate 6 4
2 Carbon dioxide
ATP
Reduced co enzymes 3NADH
1 FADH

30. As a result of one turn of the Krebs cycle the cell makes:
Summary
As a result of one turn of the Krebs cycle the cell makes:
1 FADH2
3 NADH
1 ATP
However, each glucose produces two pyruvic acid molecules…. So the total outcome is:
2 FADH2
6 NADH
2 ATP
The key function of the Krebs cycle is to provide electrons for the Electron Transport Chain, the production of ATP is a bonus.

31. The story so far

32. Phase Three: Oxidative Phosphorylation
Function: Extract energy (in the form of electrons) from NADH and FADH2 in order to add a phosphate group to ADP to make ATP.
Location: Mitochondria cristae.

33. Oxidative Phosphorylation
Requires
NADH or FADH2
ADP and P O2

34. Electron Transport Chain Uses NADH
During the electron transport chain, H+ is moved against a gradient.
The energy needed to do this is supplied by electrons carried by NADH

35. What happens along the inner membrane of the mitochondria?
The loss of electrons from NADH result in the addition of energy to protein pumps in the membrane resulting in a H+ being moved from the inside to the outside of the inner membrane
This happens many times creating an imbalance (gradient) of H+.
Oxygen pulls electrons to keep them moving.

36. What happens along the inner membrane of the mitochondria?
ATP is made as H+ ions are allowed back into the matrix of the mitochondria by a different protein (ATP synthase).
The energy released by the “rush” of H+ is used by this enzyme to make ATP (kind of like a rush of water in a stream being used to turn a water wheel).
Ultimately, aerobic respiration produces ~36 ATP molecules from each individual glucose molecule.

37. The Electron Transport Chain

38. Cytochrome c Cytochrome c:
is one of the proteins of the electron transport chain;
exists in all living organisms;
is often used by geneticists to determine relatedness.

39. Chemiosmotic Hypothesis
Biologists still don’t know exactly how ATP is made.
The best theory we have is called the Chemiosmotic Hypothesis.

40. The Chemiosmotic Hypothesis
proposes that the Electron Transport Chain energy is used to move H+ (protons) across the cristae membrane, and
that ATP is generated as the H+ diffuse back into the matrix through ATP Synthase.

41. Electron Transport Chain
FAD enters here so 2 ATP produced
Reduced
Carrier 3
Carrier 2
Carrier 4
Reduced NAD
Water
NAD
ATP
ATP
ATP
Oxygen
Reduced
Carrier 2
Carrier 3
Reduced
Carrier 4

42. ATP Sum 10 NADH x 3 = 30 ATPs 2 FADH2 x 2 = 4 ATPs
2 ATPs (Gly) = ATPs
2 ATPs (Krebs) = 2 ATPs
Max = 38 ATPs per glucose

43. However...
Some energy (2 ATP’s) is used to shuttle the NADH from Glycolysis into the mitochondria…..So, some biologists teach there is an actual ATP yield of 36 ATP’s per glucose.

44. The Final story