Imagine that oleic acid in the cytosol of a cell is activated and then transport
ID: 269027 • Letter: I
Question
Imagine that oleic acid in the cytosol of a cell is activated and then transported into the matrix of the mitochondrion where it undergoes beta-oxidation. How many net ATPs can ultimately be made via this process? Assume the resulting acetyl-CoAs are run through the Krebs Cycle, and assume that all reduced cofactors from beta-oxidation and the Krebs Cycle are processed through the electron transport chain. Consider GTP to be the equivalent of ATP.
***The answer is 118.5. I just need to know how to get there!***
Explanation / Answer
Oleic acid is 18 carbon compounds and thus it produces 9 acetyl CoA through beta oxidation. This requires 8 round of beta oxidaion. 1 molecule of NADH is produced by each cycle of beta oxidation and thus 8 molecules of NADH are produced. 7 molecues of FADH2 are produced by 8 round of beta oxidation. Thus total outcome is: 9 Acetyl CoA, 8 NADH and 7 FADH2.
Each acetyl CoA produces 3 NADH, 1 FADH2 and one molecule of GTP (ATP) through Krebs cycle. Thus, total number of NADH produced by 9 acetyl CoA = 27 and total number of FADH2 = 9 and total number of GTP (ATP) = 9.
Thus, one molecule of oleic acid finally produces:
NADH = 27 + 8 = 35
FADH2 = 9 + 7 =16
ATP = 9
Thus, total ATP = 87.5 + 16 + 9 = 120.5 (1 NADH = 2.5 ATP and 1 FADH2 = 1.5 ATP)
2 ATPs are used in activation of fatty acids. Hence net ATP = 120.5 - 2 = 118.5