Final answer:
To calculate the number of ATP molecules produced from the beta-oxidation of eicosanoic acid, the formula ((0.5 × number of carbons - 1) × 14) + 10 - 2 is used. Eicosanoic acid, with 20 carbons, yields 138 ATP molecules after accounting for the cycles of beta-oxidation, the ATP produced, and the initial activation step.
Step-by-step explanation:
The question asks for the calculation of the total number of ATP molecules produced from the complete beta-oxidation of eicosanoic acid, a fatty acid with 20 carbon atoms. To determine this, we use the formula that calculates ATP yield for fatty acids: ((0.5 × n - 1) × 14) + 10 - 2, where n is the number of carbon atoms in the fatty acid.
Firstly, we determine the number of ß-oxidation cycles needed for eicosanoic acid by dividing the number of carbon atoms by two and subtracting one (n/2 - 1). Eicosanoic acid has 20 carbons, so it will undergo (20/2 - 1) = 9 cycles of ß-oxidation. Each of these cycles generates 14 ATP (from 1 FADH₂ and 1 NADH via oxidative phosphorylation, and 1 acetyl-CoA through the TCA cycle). Adding the ATP yield from the last two acetyl-CoA molecules, we get a total of (9 × 14) + 10 ATP. We also need to account for the 2 ATP used in the initial activation step to form eicosanoyl-CoA, subtracting 2 ATP from our total. Altogether, this gives us (9 × 14) + 10 - 2 = 138 ATP molecules produced from the complete beta-oxidation of eicosanoic acid.