If each NADHNADH generates 3 ATPATP molecules and each FADH2FADH2 generates 2 ATPATP molecules, calculate the number of ATPATP molecules generated from one saturated 18 ‑carbon fatty acid.

Explanation:

The metabolic pathway by which energy can be obtained from a fatty acid is called "beta-oxidation". In this route, acetyl-Coa is produced by removing 2 carbons from the fatty acid for each acetyl-Coa produced. In other words, for each round, 1 acetyl Coa is produced and for each round 2 carbons are removed from the initial fatty acid. Therefore, the first step is to calculate the number of rounds that will take place for an 18-carbon fatty acid using the following equation:

Where "n" is the number of carbons, in this case "18", so:

We also have to calculate the amount of Acetyl-Coa produced:

Now, we have to keep in mind that in each round in the beta-oxidation we will have the production of 1 and 1 . So, if we have 8 rounds we will have 8 and 8 .

Finally, for the total calculation of ATP. We have to remember the yield for each compound:

-)

-)

-)

Now we can do the total calculation:

We have to subtract  "2 ATP" molecules that correspond to the activation of the fatty acid, so:

In total, we will have 128 ATP.

I hope it helps!