Question

How many molecules of acyl-CoA are produced in beta-oxidation of palmitic acid

• A. Six
• B. Seven
• C. Eight
• D. Nine

Answer 1

The Correct Option is C

To understand how many molecules of acyl-CoA are produced during the beta-oxidation of palmitic acid, we need to examine the process of fatty acid oxidation, specifically beta-oxidation. 

Palmitic acid is a 16-carbon saturated fatty acid. During beta-oxidation, fatty acids are broken down through a series of reactions that progressively shorten the fatty acid by two carbon atoms at a time, in the form of acetyl-CoA.

1. Initial Step of Activation: Before beta-oxidation occurs, palmitic acid (C₁₆H₃₂O₂) is converted into palmitoyl-CoA in the presence of Coenzyme A and ATP. This step is not part of the oxidation cycle itself.
2. Beta-Oxidation Cycle: The complete beta-oxidation of one molecule of palmitoyl-CoA involves a recurring cycle of four reactions:
   • Oxidation by FAD
   • Hydration
   • Oxidation by NAD⁺
   • Thiolysis (cleavage by CoA)
3. Calculation of Acetyl-CoA Produced: Since palmitic acid has 16 carbon atoms, its complete oxidation involves seven cycles of beta-oxidation (16/2 - 1 = 7). Each of these cycles produces one molecule of acetyl-CoA, and the final cleavage of the last two-carbon fragment produces another acetyl-CoA.
4. Total Acetyl-CoA Produced: Therefore, from seven cycles of beta-oxidation and the final split, a total of eight acetyl-CoA molecules are produced.

Thus, the correct number of acetyl-CoA molecules produced is Eight.

Conclusion: Hence, the correct option is Eight, as palmitic acid undergoes seven cycles of beta-oxidation to form eight molecules of acetyl-CoA, accounting for the initial acyl-CoA and each consecutive molecule produced during the breakdown process.