1. Chapter 9 Respiration Title: 9-2 The Krebs Cycle & Electron Transport
Essential Question?
What happens during the Krebs Cycle and the Electron Transport Chain

2. Objective What happens during the Krebs cycle?
How are high-energy electrons used by the electron transport chain?

3. Overview of Respiration
At The End Of Glycolysis, 90% Of The Energy Is Still Contained In The Pyruvate Molecules. Aerobic Respiration Will Release The Energy

4. Overview of Respiration
Cellular Respiration
Is The Process That Releases Energy By Breaking Down Molecules Of Glucose In The Presence Of Oxygen.

5. In The Presence of Oxygen
Cellular Respiration
C6H12O6 + 6O2 6CO2 + 6H2O
In The Presence of Oxygen
Back Where We Started

6. The Krebs Cycle Glycolysis Happens In The Cytoplasm
Hans Krebs ( )
Forced to emigrate from Germany to England in 1933.
Noble Prize in Physiology 1953
Discovered:
Glycolysis Happens In The Cytoplasm
Pyruvic Acid Then Moves To The Mitochondria

7. Mitochondria

8. The Krebs Cycle Key Concept:
During The Krebs Cycle, Pyruvic Acid Is Broken Down Into Carbon Dioxide, In A Series Of Energy- Extracting Reactions

9. The Krebs Cycle
The Krebs Cycle
AKA
The Citric Acid Cycle

10. Citric Acid Production
The Krebs Cycle
Step A
Citric Acid Production
Pyruvic Acid (3 Carbon Compound) Enters The Mitochondria
1 Carbon becomes CO2
2 Carbons Join Coenzyme A Forming Acetyl-CoA next
2 Carbon acetyl group added forming Citric Acid (6 Carbon)

11. The Krebs Cycle Citric Acid breaks down to a 4- Carbon Molecule + 2CO2
Step B
Energy Extraction
Citric Acid breaks down to a 4- Carbon Molecule + 2CO2
High Energy Electrons Released
Electrons Captured By:
NAD+
FAD
(flavine adenine dinucleotide)

12. The Krebs Cycle
CO2-You breath it out ATP-Powers Cellular Activities NADH & FADH2-Powers Electron Transport Chain

13. Electron Transport Chain
Key Concept: The Electron Transport Chain In The Mitochondria Inner Membrane Uses High Energy Electrons From The Krebs Cycle To Convert ADP into ATP

14. Electron Transport Chain

15. Electron Transport Chain

16. Electron Transport Chain
Step A
NADH & FADH2 Release High Energy Electrons & H+
Electrons Picked Up By Carrier Proteins In The Mitochondrial Inner Membrane (Eukaryotes)
In The Cell Membrane of Prokaryotes

17. Electron Transport Chain
Step A (continued)
At The End Of The Electron Transport Chain The Electrons Must Be Passed To An Electron Acceptor – They Can Not Just Vanish
Where Do They Go??????

18. Electron Transport Chain
Step A (continued)
Oxygen Is The Final Electron Acceptor. Hydrogen Ions Are Attached And Water Is Formed
This Is Why You Need To Breath In Oxygen!

19. Electron Transport Chain
Step B
Every Time 2 High Energy Electrons Pass Through The Electron Transport Chain
H+ (Hydrogen Ions) Are Transported Into The Mitochondrial Intermembrane Space!
Intermembrane Space
Matrix

20. Electron Transport Chain
Step C
ATP Synthase
H+ Provides
Energy For
ATP Production

21. ATP = 38% Energy In 1 Glucose Heat = 62% Energy In 1 Glucose
The Totals per Glucose
Glycolysis ATP
Krebs Cycle &
Electron Transport 34 ATP
36 ATP
ATP = 38% Energy In 1 Glucose
Heat = 62% Energy In 1 Glucose

22. Energy & Exercise Quick Exercise Uses Current ATP Stores
Cell Kicks In Lactic Acid Fermentation
Provides Energy Only For About 90 Seconds

23. Energy & Exercise Quick Energy (continued)
Lactic Acid Builds Up In The Cell & MUST Be Removed
That Requires Extra Oxygen
Heavy Breathing
Sore, Tired Muscles

24. Energy & Exercise Long-Term Energy Glucose Glycogen Fats
Cellular Respiration Must Accelerate Drawing Energy From:
Glucose
Glycogen
Fats