Answer :
Final answer:
Correct option: b) 132.5 × 10²⁴. A 17-carbon saturated fatty acid going through β-oxidation produces approximately 120 mols of ATP, which is about 7.226 x 10^25 molecules. The closest option to this value is 132.5 x 10^24 molecules (option b).
Explanation:
Calculation of ATP Yield from 17-Carbon Fatty Acid Oxidation
The β-oxidation pathway involves the breakdown of fatty acids to produce ATP. For a 17-carbon fatty acid, the number of β-oxidation cycles would be 17/2 - 1 = 7.5, but since we cannot have half cycles, it runs for 8 cycles (since the last cycle yields 2 acetyl-CoA). Each cycle generates one FADH₂, one NADH, and one acetyl-CoA, which in turn yield 1.5 ATPs, 2.5 ATPs, and 10 ATPs respectively. Considering 8 cycles, the ATP yield would be:
NADH: 8 cycles x 2.5 ATP/cycle = 20 ATPs
Acetyl-CoA: 8 cycles x 10 ATP/cycle = 80 ATPs (Note that the final cycle produces an extra acetyl-CoA, so one additional 10 ATPs are produced, totaling 90 ATPs from acetyl-CoA)
Moreover, two ATPs are consumed during the initial activation of the fatty acid.
Therefore, the total ATP yield can be calculated as 12 + 20 + 90 - 2 = 120 ATPs.
However, as the question seems to be asking for the number of ATP molecules, we convert mols to molecules. One mol is 6.022 x 10^23 molecules.
So, 120 mols of ATP is equal to 120 x 6.022 x 10^23 = 7.226 x 10^25 molecules of ATP.
The answer most approximate to this value is option b) 132.5 x 10^24.
