Question

what is the first step of fatty acid syntheis is it trnasfer of acetyl coa or activation of a fatty acid to a acetyl coa

Answer 1

First step fatty acid synthesis is transfer to acetyl CoA from matrix of mitochondria to the cytosol through an acetyl CoA shuttle system. The acetyl passes out of mitochondria as citrate. Within mitochondria acetylCoA reacts with oxaloacetate to form citrate in a reactioj catalysed by citrate synthase. Under conditions where concentration of acetyl CoA and ATP are high,  Citrate leaves the mitochondria and in cytosol, reacts witg cytosolic CoA and ATP tobform acetylCoA and oxaloacetate ina reaction catalysed by citrate cleavage enzyme, citrate lyase.