1. How do cells extract energy from glucose?
Cellular Respiration
How do cells extract energy from glucose?

2. Where did Chuck Norris get all that energy from?
Cellular Respiration
Where did Chuck Norris get all that energy from?

3. What is Cellular Respiration?
An aerobic process (requires oxygen)
Uses chemical energy from glucose to make ATP
The chemical energy stored in ATP can be used throughout the cell O2
glucose 1
ATP 36
cellular resp.

4. Four Main Stages Glycolysis Pyruvate Oxidation Krebs Cycle
Anaerobic / In cytosol
breaks glucose (6C) into two pyruvate (3C)
Generates 2 ATP and 2 NADH
Pyruvate Oxidation
Pyruvate converted to acetyl CoA
Oxidative decarboxylation
Generates NADH (inside mitochondria)
Krebs Cycle
Within mitochondrial matrix
Two more oxidative decarboxylation reactions
Generates ATP, NADH and FADH2
Electron Transport Chain
Along the inner mitochondrial membrane
Uses high energy electrons from NADH and FADH2 to create an electrochemical proton (H+) gradient which powers ATP synthesis

5. Key Reactions substrate level phosphorylation
An enzyme mediated reaction that directly produces ATP
oxidative decarboxylation
The formation of CO2 coupled with the formation of NADH, FADH2 or ATP
oxidative phosphorylation
Use of a proton gradient to generate ATP using ATP synthase

6. Do Cells NEED Mitochondria?
It is possible to generate relatively small amounts of ATP relying exclusively on the reactions in the cytoplasm
Fermentation is essentially glycolysis, however, the final products are slightly modified
We will return to this process in detail after learning about cellular respiration

7. Cellular Respiration Equation
General Formula O2
glucose
CO2
H2O H+
Energy
C6H12O O2  6 CO H2O + energy
The process begins immediately when glucose enters the cytoplasm. Here, there are enzymes waiting to begin the process of glycolysis.

8. Glycolysis I The “investment” period ATP is USED to activate glucose
This is accomplished via phosphorylation reactions
Adding a phosphate group from ATP

9. Numbering The Carbons glucose
In order to keep track of how glucose is modified and rearranged during glycolysis we number each carbon C O 6 5
glucose 1 4 3 2

10. Glycolysis (I) glucose glucose-6-phosphate fructose-6-phosphate
fructose-1-6-bisphosphate
2 molecules of
G3P (glyceraldehyde-3-phosphate) P P P C O C O P C O P P P C O P P C P C P

11. Glycolysis (I) glucose glucose-6-phosphate fructose-6-phosphate
fructose-1-6-bisphosphate
2 molecules of
G3P (glyceraldehyde-3-phosphate)
ATP
ADP P C O C O P
ATP
ADP C O P P C P C P

12. Glycolysis (II) The “pay-off” period
ATP and NADH (a temporary high energy carrier) are PRODUCED during glycolysis II
By the end of glycolysis II, glucose has been broken down to two 3 carbon compounds called pyruvate (pyruvic acid)

13. Glycolysis (II) G3P glyceraldehyde-3-phosphate
PGAP 1,3-bisphosphoglycerate
PGA
3 - phosphoglycerate
PEP
phosphoenolpyruvate
Pyruvate C P C P
NAD
NAD Pi Pi
NADH
NADH C P P P P P P C P P C P
H2O H
H2O H C P P P P P P C

14. Glycolysis (II) G3P PGAP PGA PEP Pyruvate glyceraldehyde-3-phosphate
1,3-bisphosphoglycerate
PGA
3 - phosphoglycerate
PEP
phosphoenolpyruvate
Pyruvate C P C P
NADH
NADH C P P
ATP
ATP C P
H2O H
H2O H C P C
ATP
ATP C

15. 2 2 Summing Up Glycolysis Used 2 ATP, but made 4 ATP Net Gain: and
Glycolysis I
Glycolysis II
Used 2 ATP, but made 4 ATP
Net Gain:
and
ATP 2
NADH 2
(high energy molecule)

16. Glycolysis: Overall Reaction
C6H12O6 + 2ADP + 2P + 2NAD+  2C3H4O3 + 2NADH + 2ATP
glucose (6C)
pyruvate (3C)
Notice: There is no oxygen used in glycolysis. It is an anaerobic process O2

17. The POWER HOUSE!
Glycolysis (in the cytosol) produces only 2 ATP per glucose
This means that more ATP are made in the mitochondria!
How does pyruvate get in there and what happens inside!?
nucleus
cytosol
ATP
ATP
mitochondria
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP

18. Mitochondria
On a separate page draw a labeled diagram of a mitochondrion
outer membrane
inner membrane
matrix
Kreb’s H+
intermembrane space
ETC
cristae

19. Mitochondria in 3D

20. Electron Micrograph of Mitochondria

21. Pyruvate Oxidation
pyruvate translocase

22. multi-enzyme pyruvate dehydrogenase complex
Pyruvate Oxidation
NAD+
NADH
Decarboxylation
Oxidation
Attachment (of coenzyme A)
ENERGY
CO2
multi-enzyme pyruvate dehydrogenase complex

23. multi-enzyme pyruvate dehydrogenase complex
Pyruvate Oxidation
NADH
Acetyl-CoA
multi-enzyme pyruvate dehydrogenase complex
Decarboxylation
Oxidation
Attachment (of coenzyme A)

24. Pyruvate Oxidation
Pyruvate enters the mitochondria via a protein carrier called pyruvate translocase
Once inside, a multi-enzyme pyruvate dehydrogenase complex converts pyruvate into acetyl CoA via an oxidative decarboxylation
Acetyl CoA can enter Krebs cycle

25. steps 1 and 2 together are an oxidative decarboxylation
Pyruvate Oxidation
In the pyruvate oxidation, for each molecule of pyruvate:
CO2 1
is released
and
NADH 1
is produced
steps 1 and 2 together are an oxidative decarboxylation

26. steps 1 and 2 together are an oxidative decarboxylation
Pyruvate Oxidation
Remember: There are 2 pyruvates produced for each glucose. Therefore, for each glucose:
CO2 1
is released
and
NADH
is produced
CO2 2
are released
and
NADH
are prodcued X2
steps 1 and 2 together are an oxidative decarboxylation

27. Krebs / Citric Acid Cycle
Pyruvate Oxidation
Krebs Cycle

28. Krebs Cycle
In the Krebs Cycle for each molecule of pyruvate:
CO2 2
are released
and
NADH 3
ATP 1
FADH2 1
are produced

29. X2 4 6 2 2 3 1 Krebs Cycle NADH FADH2 NADH FADH2
Remember: There are 2 pyruvates produced for each glucose. Therefore, for each glucose:
CO2 4
are released
NADH 6
and
FADH2 2
ATP
are produced
CO2 2
are released
NADH 3
and
FADH2 1
ATP
are prodcued X2

30. pyruvate oxidation & Krebs Cycle
The Story So Far
pyruvate oxidation & Krebs Cycle
glycolysis
glucose 1
C – C – C
pyruvate 2
CO2 6
(6C)
(3C)
(1C)
ATP 4
ATP 2
NADH 10
NADH 2
FADH2 2

31. 2 2 2 6 4 10 2 The Story So Far Totals Glycolysis
Tracking High Energy Molecules
Metabolic Process
ATP Produced
High Energy Molecules
Glycolysis
Pyruvate Oxidation (x2)
Krebs Cycle (x2)
Totals
ATP 2
NADH
in cytosol
NADH 2
ATP 2
NADH 6
FADH2
ATP 4
NADH 10
FADH2 2

32. Oxidative Phosphorylation
NADH and FADH2 are in their high energy reduced form with an extra pair of electrons
These electrons are donated to carrier proteins in the Electron Transport Chain (ETC).
The electrons are passed from protein to protein via redox reactions
The energy from the electrons is used to pump protons (H+) into the intermembrane space of the mitochondria

33. Electron Transport Chain
not part of the ETC C
Cristae UQ
NADH
reductase
Cytochrome
b1c1
Cytochrome c
Cytochrome c
oxidase
Ubiquinone
ATP Synthase
Electron Carriers:
1. Complex I [protein]
2. Ubiquinone [non-protein]
3. Complex III
4. Cytochrome c
5. Complex IV
[protein]

34. Electron Transport Chain
Cristae UQ
To pass electrons along ETC, each carrier is reduced (gains electrons) then oxidized (donates electrons)

35. Electron Transport Chain
Cristae UQ
NAD+
NADH
NADH donates a pair of electrons to NADH reductase
electrons continue along ETC via sequential oxidations and reductions

36. Electron Transport Chain
Cristae UQ
FADH2
FADH2 donates a pair of electrons to coenzyme Q
electrons also continue along ETC

37. Electron Transport Chain
Cristae UQ
FADH2 donates a pair of electrons to coenzyme Q
electrons also continue along ETC

38. For each NADH, 6 H+ are pumped across the mitochondrion inner membrane
Cristae UQ
NAD+ H+ H+ H+ H+ H+ H+ H+
NADH H+ H+ H+ H+ H+ H+
For each NADH, 6 H+ are pumped across the mitochondrion inner membrane

39. For each NADH, 6 H+ are pumped across the mitochondrion inner membrane
Cristae UQ
H2O H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ O2
For each NADH, 6 H+ are pumped across the mitochondrion inner membrane
Oxygen is the final electron acceptor and is converted to H2O

40. H+ H+ H+ C
Cristae UQ
H2O H+ H+ H+ H+ H+ H+ H+
FADH2 H+ H+ H+ H+ O2
For each FADH2, 4 H+ are pumped across the mitochondrion inner membrane

41. The electrochemical proton gradient
High Proton Concentration H+ H+
Gradient C
Cristae UQ H+
Low Proton Concentration H+ H+ H+ H+ H+
The electrochemical proton gradient
(sometimes referred to as the proton motive force)

42. ATP synthase works a bit like a water mill

43. H+ H+ H+ H+ H+ H+ H+ C
Cristae UQ
ATP H+ H+ H+ H+ H+ H+
Using the energy stored in the proton gradient, ATP is generated using oxidative phosphorylation: formation of ATP coupled to oxygen consumption
The movement of ions along their concentration gradient across a semi-permeable membrane is known as chemiosmosis.

44. H+ H+ H+ H+ H+ H+ H+ C
Cristae UQ
ATP
ATP
ATP H+ H+ H+ H+ H+ H+
1 ATP is generated for each proton pair flowing through ATP synthase.
Pumps H+ 6 3
NADH

45. H+ H+ H+ H+ H+ H+ H+ C
Cristae UQ
ATP
ATP H+ H+ H+ H+ H+ H+
1 ATP is generated for each proton pair flowing through ATP synthase.
Pumps H+ 4 2
FADH2

46. The WHOLE process… Cristae C UQ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+

47. The WHOLE process… Cristae NAD+ NADH C UQ H+ H+ H+ H+ H+ H+ H+ H+ H+

48. The WHOLE process… Cristae C H2O O2 UQ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+

49. The WHOLE process… Cristae C ATP ATP ATP UQ H+ H+ H+ H+ H+ H+ H+ H+ H+

50. The WHOLE process… Cristae C ATP ATP ATP UQ H+ H+ H+ H+ H+ H+ H+ H+ H+

54. Remember: BEFORE the ETC we had…
Summing up ATP
Remember: BEFORE the ETC we had…
Metabolic Process
ATP Produced
High Energy Molecules
Glycolysis
Transition Reaction (x2) (oxidative decarboxylation)
Krebs Cycle (x2)
Total
ATP 2
NADH
in cytosol
NADH 2
ATP 2
NADH 6
FADH2
ATP 4
NADH 10
FADH2 2

55. In the Electron Transport Chain
Summing up ATP
In the Electron Transport Chain
Molecules from
High Energy Molecules
ATP produced in ETC
Glycolysis
Transition Reaction (x2)
Krebs Cycle (x2)
Total
NADH 2
ATP 4
in cytosol
NADH 2
ATP 6
NADH 6
FADH2 2
ATP 22 10
FADH2 2
ATP 32
NADH

56. 2 2 4 + From Glycolysis 2 2 6 6 2 22 10 2 34 32 Summing up ATP Total
IN TOTAL
Molecules from
High Energy Molecules
ATP produced in ETC
Glycolysis
Transition Reaction (x2) (oxidative decarboxylation)
Krebs Cycle (x2)
Total
ATP 2
NADH 2
ATP 4
in cytosol
From Glycolysis
ATP 2
NADH 2
ATP 6
NADH 6
FADH2 2
ATP 22 10
FADH2 2
ATP 34
ATP 32
NADH

57. 2 2 4 + From Krebs Cycle 2 2 6 6 2 22 2 10 2 36 34 Summing up ATP
IN TOTAL
Molecules from
High Energy Molecules
ATP produced in ETC
Glycolysis
Transition Reaction (x2) (oxidative decarboxylation)
Krebs Cycle (x2)
Total
ATP 2
NADH 2
ATP 4
in cytosol
From Krebs Cycle
ATP 2
NADH 2
ATP 6
NADH 6
FADH2 2
ATP 22
ATP 2 10
FADH2 2
ATP 36
ATP 34
NADH

58. glucose + oxygen carbon dioxide + water + energy
Overall Reaction
glucose 1
CO2 6
glucose
CO2
NAD+ 10
FAD 2
NADH 10
FADH2 2
NAD+ 10
FAD 2
Catalysts
ATP 36
Energy
H2O H+
H2O H+ O2 O2
glucose oxygen carbon dioxide + water + energy

59. glucose + oxygen carbon dioxide + water + energy
Overall Reaction
Phase (location)
Glycolysis (cytosol)
Transition Reaction (mito.)
Kreb’s Cycle (mito.)
ETC (mito.)
glucose 1
CO2 6
some
NAD+ 10
FAD 2
ATP 36
some
H2O H+ O2
glucose oxygen carbon dioxide + water + energy

60. Alternate Metabolic Pathways

61. Fermentation
When oxygen is NOT available, cells can metabolize pyruvate (derived from glucose) by the process of fermentation.
Two Types
(i) alcohol fermentation: pyruvate is reduced to ethyl alcohol and CO2; occurs in yeast cells
(ii) lactic acid fermentation: pyruvate reduced to lactic acid in muscle cells