Question

4. Calculate the results of the catabolism of linoleic acid, an 18-carbon fatty acid containing 2 carbon-carbon double bonds. Show your calculation to get credit. TOTAL NADH formed: ______ TOTAL FADH2 formed: - TOTAL GTP formed: --

Answer 1

- In one cycle of beta-oxidation one NADH and one FADH is synthesized and the fatty acid losses two carbon during beta-oxidation which are converted into acetyl Co-A. If the fatty acid is 18 carbon then it undergoes 7 beta-oxidation reactions and produces 7 acetyl Co-A. The last cycle which has four carbon produces two acetyl Co-A and one NADH and one FADH.

Hence overall it 18 carbon fatty acids will undergo 8 beta-oxidation reactions produced 8 NADH and 8 FADH and 9 acetyl Co-A.

Linoleic acid has two double bonds. These double bonds are in cis-position.

Enzyme $\Delta$ 3 $\Delta$ 2 converts cis bonds into trans bonds and helps in Beta oxidation.

One acetyl Co-A upon oxidation via the TCA cycle gives 3 NADH, one FADH and one GTP.

So overall NADH from TCA cycle = 3*9 = 27

FADH = 9

GTP = 9

So overall NADH = 27 + 8 = 35

FADH = 8+9 = 17.

GTP = 9.

Two ATP are used to convert fatty acid into fatty acyl Co-A.

SO, net GTP will be 7.

NADH = 35

FADH = 17

GTP = 7.

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