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Describe what occurs in the Kreb’s cycle during aerobic respiration

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cenicienta | (Level 1) Valedictorian

Posted May 19, 2012 at 4:13 PM via web

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  • Describe what occurs in the Kreb’s cycle during aerobic respiration

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cgrant2 | High School Teacher | (Level 1) Valedictorian

Posted July 13, 2012 at 3:52 AM (Answer #1)

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After Glycolysis, Kreb Cycle is the next step in cellular respiration process. Glycolysis creates a pyruvate molecule that is used in the Krebs Cycle. As you go through the process of the Krebs Cycle, its important to understand the amount of carbon that are added and taken away form the starting molecule (which is pyruvate). This will make it easier to memorize the process. The process goes as follows: 

1. Pyruvate is an 3 carbon molecule (starting molecule) 

2. CO2 is lost to form Acetyl Co-A molecule (2 carbons) 

3. Oxaloacetate (4 carbons) combines with Acetyl Co-A molecule (2 carbons) to form citrate (6 carbons). Oxaloacetate is the end result of the last Kreb Cycle. 

4. Isomer of citrate forms called isocitrate (6 carbons) 

5. CO2 is lost to form alpha-ketoglutarate (5 carbons)

6. Another CO2 is lost to form succincyl Co-A (4 carbons) 

7. Co enzyme A is released to form succinate (4 carbons) 

8. H ion is added to succinate to form fumarate (4 carbons) 

9. Fumarate undergoes hydrolysis (loss of water) to form malate (4 carbons) 

10. Malate is oxidize (add electrons or H ions) to form oxaloacetate (4 carbons) 

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