Question

Fatty acid synthesis proceeds according to the following reaction:

(n+1)acetyl-CoA+n ATP+2n NADPH ➝ CH₃·(CH₂)₂ₙ·COO⁻+nPᵢ+n ADP + 2n NADP⁺ + (n+1) CoA
where n is a positive integer. Based on this, how many ADP and NADP+ molecules will be produced during synthesis of a 16-carbon fatty acid?

A.7 ADP molecules and 14 NADP+ molecules

B.14 ADP molecules and 28 NADP+ molecules

C.8 ADP molecules and 15 NADP+ molecules[

D.16 ADP molecules and 32 NADP+ molecules

Answer 1

The question involves the biology of fatty acid synthesis, asking about the specific requirements of ATP and NADPH during this process. In summary, the formation of palmitate from acetyl-CoA and malonyl-CoA requires 8 ATP and 14 NADPH molecules through multiple cycles of reactions catalyzed by the FAS complex.

Step-by-step explanation:

The subject of your question is concerned with the synthesis of fatty acids, specifically the energy and reducing power requirements of the process. Fatty acid synthesis involves a cyclic series of reactions catalyzed by the fatty acid synthase (FAS) complex, consuming ATP and NADPH as key molecules. During the synthesis of palmitate, a 16-carbon saturated fatty acid, this process typically requires 8 molecules of adenosine triphosphate (ATP) and 14 molecules of nicotinamide adenine dinucleotide phosphate (NADPH). Each turn of the cycle extends the fatty acyl chain by two carbon units, donated from malonyl-CoA, until a 16-carbon chain is synthesized. Then, the enzyme hydrolase releases the acyl-ACP as a free fatty acid, which immediately reacts with coenzyme-A to form acyl-CoA.

Fatty acid synthesis differs from the ß-oxidation pathway, which is the process of fatty acid breakdown. The latter involves the sequential removal of two-carbon segments from acyl-CoA, generating acetyl-CoA, FADH₂, and NADH, which feed into the citric acid cycle and oxidative phosphorylation to produce ATP.