1. (c) The McGraw-Hill Companies, Inc.
Chapter 9
Biology
Sixth Edition
Raven/Johnson
(c) The McGraw-Hill Companies, Inc.

2. Overall reaction for cellular respiration:
Cellular respiration is the step-wise release of energy from molecules (usually carbohydrates) used to synthesize ATP molecules.
Oxidation of glucose is an exergonic reaction (releases energy) which drives ATP synthesis - an endergonic reaction (energy is required).
Drives ATP synthesis
Overall reaction for cellular respiration:

3. NAD+ and FAD
Each step of cellular respiration requires a separate enzyme
Some enzymes use the oxidation-reduction coenzyme NAD+ or the coenzyme FAD.

4. The NAD+ cycle Remember: When NAD+  NADH it has been reduced.
When NADH  NAD+ it has been oxidized.

5. 4 Phases of Complete Glucose Breakdown
Glycolysis - yields 2 ATP
Pyruvate oxidation – oxidation reaction
Krebs cycle – yields 2 ATP
Electron transport chain – yields ATP
Net ATP produced from respiration: 36-38

6. Outside the Mitochondria: Glycolysis
Universally found in all organisms.
Does not require oxygen.
Outside the Mitochondria: Glycolysis

7. Overview of Glycolysis
Glucose (6-C sugar)
2 ATP
2 ADP
6-C sugar diphosphate
3-C sugar-phosphate
3-C sugar-phosphate
2 ADP
2 ADP
2 ATP
2 ATP
2 NAD+
2 NAD+
2 NADH
2 NADH
3-C pyruvate
3-C pyruvate

10. Glycolysis summary Inputs: Glucose 2 NAD+ 2 ATP 4 ADP + 4 P Outputs:
2 pyruvate
2 NADH
2 ADP
4 ATP (2 net gain)

11. Pyruvate (Oxygen present) (Oxygen not present) Cellular Respiration
Fermentation
Fermentation inputs and outputs per glucose molecule
Inputs:
glucose
2 ATP
4 ADP + 4 P
Outputs:
2 lactate or 2 alcohol and 2 CO2
2 ADP
4 ATP (2 net gain)

12. 2-carbon molecule + 1 CO2
3-carbon molecule + 0 CO2

13. Pyruvate oxidation: if oxygen is present
2Pyruvate + 2CoA
2 Acetyl-CoA + 2CO2
2 NAD+
2 NADH + H+
Pyruvate is converted to a C2 acetyl group attached to coenzyme A (CoA), and CO2 is released. This occurs in the cytoplasm if oxygen is present.

14. Krebs Cycle
The Krebs cycle is a cyclical metabolic pathway located in the matrix of the mitochondria.
At the start of the citric acid cycle, CoA carries the C2 acetyl group to join a C4 molecule, and C6 citrate results.

15. Acetyl-CoA (2 C) C6 C4 C5 NADH CO2 ATP FADH2 Krebs cycle NAD+ FADH
ADP + P

18. Krebs cycle inputs and outputs per glucose molecule
2 acetyl groups
6 NAD+
2 FAD
2 ADP + 2 P
Outputs:
4 CO2
6 NADH
2 FADH2
2 ATP

19. Electron Transport Chain
The electron transport chain located in the cristae of mitochondria is a series of protein carriers
Electrons carried by NADH and FADH2 enter the electron transport chain.
As a pair of electrons is passed from carrier to carrier, energy is released and is used to form ATP molecules by oxidative phosphorylation.

22. Oxygen receives energy-spent electrons at the end of the electron transport system then combines with hydrogen to form water:
½ O2 + 2 e- + 2 H+ → H2O

23. Glucose + O2  CO2 + H2O + ATP

25. Remember: Electrons = Energy
NAD+
NADH
Glycolysis
Transition
Reaction
Krebs
Cycle
Electron
Transport
Chain
Remember: Electrons = Energy

28. Feedback mechanisms

30. Acidic group
H group
Amino group
R-group

31. With Beta-oxidation the last two carbons of a fatty acid chain enter the Krebs cycle.
This process is repetitive until the entire fatty acid chain is consumed.
A 6 Carbon fatty acid molecule produces more ATP than a glucose (based on the amount of NADH and FADH2 produced.

32. When PEP transfers a phosphate group to ADP, pyruvate is formed
When PEP transfers a phosphate group to ADP, pyruvate is formed. This is called substrate level phosphorylation.

33. ADP and PEP are substrates and an enzyme facilitates the transfer of a phosphate group from PEP to ADP to create ATP. The energy in the bond is conserved.

34. The End.