Which of the following is NOT required in he synthesis of fa
 Which of the following is NOT required in he synthesis of fatty acids? and why? 
 Acetyl-CoA
 Biotin
 HCO3- (CO2)
 Malonyl-CoA
 NADH
  Which of the following is NOT required in he synthesis of fatty acids? and why? 
 Acetyl-CoA
 Biotin
 HCO3- (CO2)
 Malonyl-CoA
 NADH
 Acetyl-CoA
 Biotin
 HCO3- (CO2)
 Malonyl-CoA
 NADH
Solution
Fatty acid synthesis does not require NADH; instead, NADPH is required. Malonyl-CoA is also not required.
Fatty acids (FA)are synthesized from acetyl-CoA and NADPH. In the first step of FA synthesis, acetyl-CoA carboxylase adds CO2to acetyl-CoA. The enzyme acetyl-CoA carboxylase requires biotin for its activity. Addition of CO2 to acetyl-CoA forms malonyl-CoA, which is the first committed intermediate in FA synthesis.
The correct answers are malonyl-CoA and NADH; if you have to choose only one, the answer is NADH because NADH is not at all involved. On the other hand, though not strictly required, FA synthesis cannot proceed without the formation of malonyl-CoA.

