1. 5.6 Krebs/Citric Acid Cycle
Unit 5: Cell Energy
5.6 Krebs/Citric Acid Cycle

2. In the presence of oxygen, pyruvic acid produced in glycolysis passes to the second stage of cellular respiration

3. Krebs/Citric Acid Cycle
Second set of reactions in cellular respiration in which pyruvic acid is broken down into carbon dioxide
Because citric acid is the first compound formed in this series of reactions, is it also known as the citric acid cycle.

4. Summary
Takes place in the mitochondrial matrix

5. Summary
Aerobic

6. Summary Starts with pyruvic acid from glycolysis
1 Carbon from pyruvic acid becomes part of carbon dioxide and is eventually released into the air
The other 2 carbons form acetic acid, which bonds to coenzyme A to produce acetyl CoA.
Acetyl CoA reacts to form citric acid (6 carbon molecule)

7. Krebs Cycle! Pyruvic Acid (3 Carbon)
Bonds with Coenzyme A to create Acetyl CoA (2 Carbon)
Becomes part of CO2 and is eventually released into the air
Reacts with oxaloacetate to form citric acid (6 Carbon)
Krebs Cycle!

8. Summary
As the cycle continues, citric acid is broken down (to a 4 carbon molecule)
Carbon dioxide and energy are released
The molecule needed to start the reactions of the cycle is remade with every turn (oxaloacetate)

9. ATP

10. Summary
Each starting molecule of glucose results in two complete turns of the Krebs Cycle
Glycolysis produces 2 molecules of pyruvic acid from 1 molecule of glucose, allowing the cycle to run twice.

12. Production One turn through the cycle produces:
Two turns through the cycle produces:
3 NADH
1 FADH2
1 ATP
2 CO2
6 NADH
2 FADH2
2 ATP
4 CO2

13. ATP