Objective 7:  Given a saturated, straight chain fatty acid, be able to calculate the number of molecules of Acetyl-CoA, FADH2, and NADH produced by B-oxidation. How much ATP would this be equivalent to?

Figures 23.6 and 23.7 in your text will help you answer this objective.  For this example, we assume that we start with a saturated fatty and convert all the carbon atoms into acetyl CoA.

If you start with a fatty acyl CoA that contains N carbon atoms, then you will go through B-oxidation (N/2)-1 times.  For example, if you start with stearoyl CoA, the stearoyl group contains 18 carbon atoms so N would equal 18.  The fatty acyl group would pass through B-oxidation (18/2)-1 = 8 times.

Each time the fatty acyl group passes through B-oxidation, 1 FAD(2H) and 1 NADH are produced.  The energy in 1 FAD(2H) and 1 NADH is equivalent to converting 4 ADPs to 4 ATPs so we say it is equivalent to 4 ATPs

If we pass through 8 times, we produce 8 X 4 or 32 ATPs and 9 acetyl CoAs

Note that you have to be careful about the question.  You might be asked how much energy is produced from stearate (potassium stearate).  In this case you would have to activate the fatty acid to stearoyl CoA before running B-oxidation.  The reaction for activation of a fatty acid follows:

Stearate + CoA + ATP = Stearoyl CoA + AMP + PPi
PPi + H2O = 2Pi

Since the PPi (pyrophosphate) is almost always hydrolyzed to 2Pi, this reaction uses two high energy bonds.  We say that 2 ATPs were used in the activation reaction.

So, if we start with stearate, we would produce 32 – 2 = 30 ATPs

Again, you have to be careful about the question. If the question asked for the total oxidation of fatty acid to CO2 and H2O, then you would have to add 10 ATPs of each acetyl CoA entering the TCA cycle.