1. Cellular Respiration
Cellular respiration breaks down glucose molecules and banks their energy in ATP
The process uses O2 and releases CO2 and H2O
Glucose
Oxygen gas
Carbon dioxide
Water
Energy
Figure 6.2A

2. glucose
GLYCOLYSIS
pyruvate

3. Efficiency of Cellular Respiration
Energy released from glucose banked in ATP
Energy released from glucose (as heat and light)
Gasoline energy converted to movement
100%
About 40%
25%
Burning glucose in an experiment
“Burning” glucose in cellular respiration
Burning gasoline in an auto engine
Figure 6.2B

4. BASIC MECHANISMS OF ENERGY RELEASE
Glucose gives up energy as it is oxidized
Loss of hydrogen atoms
Energy
Glucose
Gain of hydrogen atoms
Figure 6.4

5. Hydrogen Carriers Such as NAD+ Shuttle Electrons
Enzymes remove electrons from glucose molecules and transfer them to a coenzyme
OXIDATION
Dehydrogenase and NAD+
REDUCTION
Figure 6.5

6. Redox reactions release energy when electrons “fall” from a hydrogen carrier to oxygen
As electrons move from carrier to carrier, their energy is released in small quantities
Energy released and now available for making ATP
ELECTRON CARRIERS of the electron transport chain
Electron flow
Figure 6.6

7. Two Mechanisms Make ATP
Cells use the energy released by “falling” electrons to pump H+ ions across a membrane
The energy of the gradient is harnessed to make ATP by chemiosmosis
High H+ concentration
ATP synthase uses graient energy to make ATP
Membrane
Electron transport chain
ATP synthase
Energy from
Low H+ concentration
Figure 6.7A

8. Organic molecule (substrate) New organic molecule (product)
ATP can also be made by transferring phosphate groups from organic molecules to ADP
Enzyme
Adenosine
Organic molecule (substrate)
This process is called substrate-level phosphorylation
Adenosine
New organic molecule (product)
Figure 6.7B

9. Impacts, Issues

10. inner compartment
outer compartment
cytoplasm
outer mitochondrial membrane
inner mitochondrial membrane

11. Transfer Phosphorylation Typical Energy Yield: 36 ATP
CYTOPLASM
glucose
ATP 2
ATP 4
Glycolysis
e- + H+
(2 ATP net)
2 NADH
2 pyruvate
e- + H+
2 CO2
2 NADH
e- + H+
8 NADH
4 CO2
Krebs Cycle
e- + H+ 2
ATP
2 FADH2 e-
Electron
Transfer Phosphorylation 32
ATP H+
water
e- + oxygen
Typical Energy Yield: 36 ATP

12. Energy-Requiring Steps of Glycolysis fructose1,6-bisphosphate
2 ATP invested
Energy-Requiring Steps of Glycolysis
glucose
ADP P
ATP
glucose-6-phosphate P
fructose-6-phosphate
ATP
fructose1,6-bisphosphate P
ADP
PGAL P

13. 1,3-bisphosphoglycerate
PGAL P
NAD+
NADH Pi
1,3-bisphosphoglycerate P
ADP
ATP P
3-phosphoglycerate P
2-phosphoglycerate
H2O P
PEP
ADP
ATP
pyruvate

14. pyruvate coenzyme A (CoA) NAD+ NADH carbon dioxide CoA acetyl-CoA
PREPARATORY STEPS
pyruvate
coenzyme A (CoA)
NAD+
NADH O O
carbon dioxide
CoA
acetyl-CoA

15. An overview of cellular respiration
High-energy electrons carried by NADH
GLYCOLYSIS
ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS
KREBS CYCLE
Glucose
Pyruvic acid
Cytoplasmic fluid
Mitochondrion
Figure 6.8

16. Glycolysis harvests chemical energy by oxidizing glucose to pyruvic acid
Figure 6.9A

17. PREPARATORY PHASE (energy investment)
Steps – A fuel molecule is energized, using ATP.
Glucose 1 3
Details of glycolysis
Step 1
Glucose-6-phosphate 2
Fructose-6-phosphate 3
Fructose-1,6-diphosphate
Step A six-carbon intermediate splits into two three-carbon intermediates. 4 4
Glyceraldehyde-3-phosphate (G3P)
ENERGY PAYOFF PHASE 5
Step A redox reaction generates NADH. 5
1,3-Diphosphoglyceric acid (2 molecules) 6
Steps – ATP and pyruvic acid are produced.
3-Phosphoglyceric acid (2 molecules) 6 9 7
2-Phosphoglyceric acid (2 molecules) 8
2-Phosphoglyceric acid (2 molecules) 9
Pyruvic acid
Figure 6.9B
(2 molecules per glucose molecule)

18. Pyruvic acid is chemically groomed for the Krebs cycle
Each pyruvic acid molecule is broken down to form CO2 and a two-carbon acetyl group, which enters the Krebs cycle
Pyruvic acid
Acetyl CoA (acetyl coenzyme A)
CO2
Figure 6.10

19. Krebs Cycle Oxidizes Organic Fuel making NADH & FADH2
Acetyl CoA
The Krebs cycle is a series of reactions in which enzymes strip away electrons and H+ from each acetyl group 2
KREBS CYCLE
CO2
Figure 6.11A

20. Alpha-ketoglutaric acid
2 carbons enter cycle
Oxaloacetic acid 1
Citric acid
CO2 leaves cycle 5
KREBS CYCLE 2
Malic acid 4
Alpha-ketoglutaric acid 3
CO2 leaves cycle
Succinic acid
Step
Acetyl CoA stokes the furnace
Steps and
NADH, ATP, and CO2 are generated during redox reactions.
Steps and
Redox reactions generate FADH2 and NADH. 1 2 3 4 5
Figure 6.11B

21. =CoA acetyl-CoA oxaloacetate citrate CoA KREBS CYCLE NAD+ NADH
isocitrate
H2O
H2O
malate O
NAD+
NADH
a-ketoglutarate
FAD
FADH2
fumarate
succinyl-CoA O
CoA
NAD+
NADH
succinate
ADP + phosphate group
ATP

22. ELECTRON TRANSPORT CHAIN
Protein complex
Intermembrane space
Electron carrier
Inner mitochondrial membrane
Electron flow
Mitochondrial matrix
ELECTRON TRANSPORT CHAIN
ATP SYNTHASE
Figure 6.12

23. Electron transfer phosphorylation
Bonus
Electron transfer phosphorylation
OUTER COMPARTMENT
NADH
INNER COMPARTMENT

24. Electron transfer phosphorylation
Bonus
Electron transfer phosphorylation
ATP
INNER
COMPARTMENT
ADP + Pi

25. Certain poisons interrupt cellular respiration
Rotenone
Cyanide, carbon monoxide
Oligomycin
ELECTRON TRANSPORT CHAIN
ATP SYNTHASE
Figure 6.13

26. Figure 6.5 Page 87 glucose 2 ATP 2 PGAL NAD+ 4 ATP 2 ATP Krebs cycle
2 NADH
2 pyruvate
2 NADH2
2 CO2
2 acetyl-CoA
2 NADH H+ H+
2 ATP
6 NADH
Krebs
cycle
ATP H+
2 FADH2
ATP H+
4 CO2
36 ATP H+ H+
electron
transfer
phosphorylation
ADP
+Pi H+ H+ H+

27. Each Glucose Yields Lots of ATP
For each glucose molecule that enters cellular respiration, chemiosmosis produces up to 38 ATP molecules
Cytoplasmic fluid
Mitochondrion
Electron shuttle across membranes
KREBS CYCLE
GLYCOLYSIS
2 Acetyl CoA
2 Pyruvic acid
KREBS CYCLE
ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS
Glucose
by substrate-level phosphorylation
used for shuttling electrons from NADH made in glycolysis
by substrate-level phosphorylation
by chemiosmotic phosphorylation
Maximum per glucose:
Figure 6.14

28. Anaerobic Respiration:
Alcohol Fermentation
Pyruvic acid is converted to CO2 and ethanol
This recycles NAD+ to keep glycolysis working
released
GLYCOLYSIS
2 Pyruvic acid
2 Ethanol
Glucose
Figure 6.15A
Figure 6.15C

29. 2 ATP net 2 pyruvate energy output energy input ATP NADH 2 NAD+
2 ADP
2 pyruvate 4
energy output
energy input
GLYCOLYSIS
ATP
C6H12O6
NADH
2 NAD+
electrons, hydrogen from NADH
2 ethanol
ETHANOL FORMATION
2 acetaldehyde
2 CO2
2 H2O

30. Anaerobic Respiration: Lactic Acid Fermentation
Pyruvic acid is converted to lactic acid
Lactic acid fermentation is used to make cheese and yogurt
GLYCOLYSIS
2 Pyruvic acid
2 Lactic acid
Glucose
Figure 6.15B

31. ATP
C6H12O6
NADH
2 NAD+ 2
2 ADP
2 pyruvate 4
energy output
energy input
GLYCOLYSIS
2 ATP net
2 lactate
electrons, hydrogen from NADH
LACTATE FORMATION

32. ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS
Pathways of molecular breakdown
Food, such as peanuts
Polyscaccharides
Fats
Proteins
Sugars
Glycerol
Fatty acids
Amino acids
Amino groups
Pyruvic acid
ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS
Glucose
G3P
Acetyl CoA
KREBS CYCLE
GLYCOLYSIS
Figure 6.16

33. FOOD
fats
glycogen
complex
carbohydrates
proteins
fatty
acids
glycerol
simple sugars
amino acids
glucose-6-phosphate
NH3
carbon
backbones
GLYCOLYSIS
PGAL
urea
pyruvate
acetyl-CoA
KREBS
CYCLE