Calculate the number of repetitions of the β-oxidation pathway required to fully convert a 18-carbon activated fatty acid to acetyl-scoa molecules.

The answer is 5. An acetyl group (comprising two C atoms) is divided off the original fatty acyl-SCoA with each recurrence of the beta-oxidation spiral. So, the first repetition of the beta-oxidation produces one acetyl-SCoA molecule and a fatty acyl-SCoA molecule that is two carbon atoms smaller than the initial fatty acyl-SCoA. There will be five acetyl-SCoA molecules made by the fifth repetition.