lecture 3

Question 1

post pyruvate oxidation

Answer 1

• citric acid cycle completes oxidation of organic molecule

Question 2

pyruvate oxidation

Answer 2

• pyruvate dehydrogenase complex (PDC) catalyse 3 rxns:
  – CO2 released
  – NAD+ reduced forming NADH
  – CoA attatched to 2-C molecule forming acetyl (CoA)

Question 3

citric acid cycle

Answer 3

• oxidises organic fuel derived from pyruvate
  – 1 ATP
  – 3 NADH
  – 1 FADH2
• eight steps each catalysed by specific enzyme
• NADH and FADH2 produced relay electrons extracted from food to electron transport chain
• closed loop

Question 4

steps of citric acid cycle

Answer 4

• citrate synthase
  – acetyl grp of CoA joins cycle combining with oxaloacetate (forms citrate)
• aconitase
  – molecules rearranged to produce isomer
• isocitrate dehydrogenase
  – redox rxn produce NADH
  – CO2 released
• alpha-ketoglutarate dehydrogenase
  – another CO2 released
  – redox produces NADH then Co-A attached
• succinyl-CoA-synthesase
  – P-grp displaces S-CoA
  – later generates ATP
• succinic dehydrogenase
  – redox rxn reducing FAD
• fumarase
  – addition of H2O molecule
• malate dehydrogenase
  – redox rxn producing NADH

Question 5

energy output

Answer 5

• glycolysis
  – 0 ATP
  – 2 NADH
• oxidation of pyruvate
  – 2 ATP
  – 6 NADH; 2 FADH2
• citric acid cycle
  – 4 ATP
  – 10 NADH; 2 FADH2