Kreb's Cycle

Question 1

Where does the kreb’s cycle occur?

Answer 1

Mitochondrial Matrix

Question 2

What happens in the Kreb’s Cycle?

Answer 2

• Acetyl CoA
• Enters circular pathway from link reaction
• (if acetyl CoA is formed from fatty acids or amino acids then it enters kreb’s cycle from other metabolic pathways)
• 4C Oxaloacetate accepts Acetyl fragment from Acetyl CoA forming 6C Citrate
• Coenzyme A is released
• Citrate converted back to oxaloacetate through series of oxidation and reduction reactions

Question 3

How is Oxaloacetate regenerated?

Answer 3

• 2 Decarboxylations of Citrate (2 CO2 released)
• 4 Oxidations (dehydrogenations) of citrate (H atoms reduce 3 NAD and 1 FAD molecules)
• Phosphate transferred from one of the 5C intermediates (after decarboxylation) to ADP forming ATP molecule

Question 4

What are the products for the Kreb’s Cycle?

Answer 4

For 1 Acetyl CoA molecule
1 ATP
2 CO2
1 FADH2
3 NADH