Questions: How many ATP molecules are produced from the complete catabolism of 4 molecules of glycerol, HOCH2 CH(OH) CH2 OH? ATP molecule(s)

To determine the number of ATP molecules produced from the complete catabolism of 4 molecules of glycerol, we need to understand the metabolic pathway of glycerol and the ATP yield from its complete oxidation.

1. Glycerol Metabolism Overview:

   • Glycerol is first converted to glycerol-3-phosphate by the enzyme glycerol kinase, consuming 1 ATP.
   • Glycerol-3-phosphate is then oxidized to dihydroxyacetone phosphate (DHAP) by glycerol-3-phosphate dehydrogenase, producing 1 NADH.
   • DHAP is an intermediate in glycolysis and can be further metabolized through glycolysis, the citric acid cycle (TCA cycle), and oxidative phosphorylation.

2. ATP Yield Calculation:

   • Glycerol to DHAP:
     • 1 ATP is consumed in the conversion of glycerol to glycerol-3-phosphate.
     • 1 NADH is produced in the conversion of glycerol-3-phosphate to DHAP.
   • Glycolysis:
     • Each DHAP molecule yields 1 ATP (net) and 1 NADH when converted to pyruvate.
   • Pyruvate to Acetyl-CoA:
     • Each pyruvate molecule yields 1 NADH when converted to acetyl-CoA.
   • Citric Acid Cycle:
     • Each acetyl-CoA yields 3 NADH, 1 FADH2, and 1 GTP (which is equivalent to 1 ATP).

3. ATP Yield from NADH and FADH2:

   • Each NADH yields approximately 2.5 ATP.
   • Each FADH2 yields approximately 1.5 ATP.

Now, let's calculate the total ATP yield for one molecule of glycerol:

• Glycerol to DHAP:

  • -1 ATP (consumed)
  • +1 NADH (produced) → 1 NADH × 2.5 ATP/NADH = 2.5 ATP

• Glycolysis (from DHAP to pyruvate):

  • +1 ATP (net)
  • +1 NADH (produced) → 1 NADH × 2.5 ATP/NADH = 2.5 ATP

• Pyruvate to Acetyl-CoA:

  • +1 NADH (produced) → 1 NADH × 2.5 ATP/NADH = 2.5 ATP

• Citric Acid Cycle (from one acetyl-CoA):

  • +3 NADH (produced) → 3 NADH × 2.5 ATP/NADH = 7.5 ATP
  • +1 FADH2 (produced) → 1 FADH2 × 1.5 ATP/FADH2 = 1.5 ATP
  • +1 GTP (equivalent to 1 ATP) = 1 ATP

Summing these up for one molecule of glycerol:

• ATP from glycerol to DHAP: -1 + 2.5 = 1.5 ATP
• ATP from glycolysis: 1 + 2.5 = 3.5 ATP
• ATP from pyruvate to acetyl-CoA: 2.5 ATP
• ATP from citric acid cycle: 7.5 + 1.5 + 1 = 10 ATP

Total ATP per glycerol molecule: 1.5 + 3.5 + 2.5 + 10 = 17.5 ATP

For 4 molecules of glycerol: 4 × 17.5 ATP = 70 ATP

Therefore, the answer is: 70 ATP molecules

Summary: The complete catabolism of 4 molecules of glycerol produces 70 ATP molecules.