Topic A6

Question 1

Citric acid cycle

Steps

Answer 1

Question 2

Citric acid cycle

Location

Answer 2

Mitochondrial matrix of each cell type (ø RBC)

Question 3

Citric acid cycle

Energy balance

Answer 3

2 ATP x 2

1 FADH₂ x 2

3 NADH+H⁺ x 2

2 CO₂

12 ATP / cycle

Question 4

Citric acid cycle

Regulation

Answer 4

• Citrate synthease
  
  • NADH+H⁺ ⊖
  • ATP ⊖
  • Fatty acyl CoA ⊖
  • AcCoA ⊕
  • ADP ⊕
  • NAD⁺ ⊕
• Isocitrate dehydrogenase
  
  • NADH+H⁺ ⊖
  • ATP ⊖
  • ADP ⊕
  • NAD ⊕
• Succinate dehydrogenase
  
  • Succinate ⊕
  • Oxaloacetate ⊖

Question 5

Citric acid cycle

Importance

Answer 5

• Energy source for body
• The NADH+H⁺ ← FADH₂ molecules carry electrones to electron transport chain (respiratory chain) for further ATP production via oxidative phosphorylation
  
  • Succinate dehydrogenase forms Complex II of chain