1. Chapter 9:
Cellular Respiration:
Harvesting Chemical Energy

2. Principles of Energy Harvest
Catabolic pathway
Aerobic Cellular Respiration (usually)
C6H12O6 + 6O2 ---> 6CO2 + 6H2O + E
E = ATP + heat

4. Redox reactions Oxidation-reduction OIL RIG
Oxidation is e- loss; reduction is e- gain
Reducing agent: e- donor
Oxidizing agent: e- acceptor

5. Oxidizing agent in respiration
NAD+: reduced to NADH
Removes electrons from food
Enzyme: dehydrogenase
Oxygen is final e- acceptor

7. Electron transport chains
E- carrier molecules (membrane proteins)
Shuttle e-s:
E- energy builds ATP
Sequence of reactions:
prevent E release in 1 explosive step
Electron route:
food---> NADH---> ETC---> O2

9. BioFlix: Cellular Respiration
Glycolysis:
cytosol, degrades glucose into pyruvate
Kreb’s Cycle:
mitochondrial matrix, pyruvate into CO2
Electron Transport Chain:
Cristae
E-’s passed to oxygen
BioFlix: Cellular Respiration

11. Glycolysis 1 Glucose ---> 2 pyruvate molecules
Energy investment phase:
Use ATP to start rxn
Energy payoff phase:
ATP made by substrate-level phosphorylation
NAD+ reduced to NADH by food oxidation
Net E yield per glucose molecule:
2 ATP + 2 NADH, no CO2
occurs aerobically or anaerobically

13. Kreb’s Cycle If molecular oxygen is present…….
Each pyruvate is converted into acetyl CoA (begin w/ 2):
CO2 is released
NAD+ ---> NADH
coenzyme A (from B vitamin), makes molecule very reactive

14. Kreb’s Cycle Cont.
Each turn: 2 C atoms enter (acetyl CoA) and 2 exit (carbon dioxide)
Oxaloacetate regenerated (“cycle”)
Per pyruvate (acetyl CoA):
3 NAD+ reduced to NADH
1 FAD reduced to FADH2
1 ATP molecule

16. Electron transport chain
Cytochromes carry e-s from carrier molecules (NADH & FADH2) to O2
Chemiosmosis: E coupling mechanism
ATP synthase:
makes ATP using proton-motive force in inner membrane space due to ETC
Enzyme uses flow of H+ back into the matrix to make ATP (oxidative phosphorylation)

18. Review: Cellular Respiration
Glycolysis:
2 ATP (substrate-level phosphorylation)
Kreb’s Cycle:
2 ATP (SL phosphorylation)
ETC & oxidative phosphorylation:
2 NADH (glycolysis) = 6ATP
2 NADH (acetyl CoA) = 6ATP
6 NADH (Kreb’s) = 18 ATP
2 FADH2 (Kreb’s) = 4 ATP
36-38 TOTAL ATP/glucose
BioFlix

20. Related metabolic processes
Fermentation:
alcohol: pyruvate to ethanol
lactic acid: pyruvate to lactate
Both regenerate NAD+ to cont. glycolysis
Neither generates additional ATP
Facultative vs. Obligative anaerobes (yeast/bacteria)
Animation: Fermentation Overview

22. Regulating Respiration
Feedback inhibition
If ATP conc. drops, respiration increases;

23. You should now be able to:
Explain in general terms how redox reactions are involved in energy exchanges
Name the three stages of cellular respiration; for each, state the region of the eukaryotic cell where it occurs and the products that result
In general terms, explain the role of the electron transport chain in cellular respiration
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

24. Distinguish between fermentation and anaerobic respiration
Explain where and how the respiratory electron transport chain creates a proton gradient
Distinguish between fermentation and anaerobic respiration
Distinguish between obligate and facultative anaerobes
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings