Question

Unsaturated fatty acids are (more or less) oxidied than saturated acids. Which yields more energy?

How is acetyl-Coa used in liver cells? in what process/ what does it produce

Answer 1

Ans.

Unsaturated fatty acids yields less energy comparitively to that of saturated fatty acids.Inorder to oxidize the double bonds in a saturated fatty acids, a reducing agent is required, which consumes less energy when compared to the double bonds which is in cis position in an unsaturated fatty acids.The presence of double bonds in unsaturated fatty acids in cis position does not favour beta oxidation completely.To break this double bond an extra reaction coupled by an enzyme is required, which itself consumes energy.This is beacuase inorder to continue the oxidization the molecule need to be transformed into a trans fat by shifting the position of bonds. This requirement of energy is an an extra expenditure and hence the net energy yield is less in comparison to saturated fatty acids.

Acetyl-CoA is a two carbon acetyl unit produced by the oxidative decarboxylation of pyruvate (formed by glycolysis),catalyzed by pyruvate dehydrogenase in the mitochondrial cells. This mitochondrial acetyl-CoA is used as an alternate source of energy/fuel for the brain or heart when enough carbohydrate for that function is not available. This is done through the synthesis of acetoacetate and Beta-hydroxybutyrate (Ketone bodies).Also, Acetyl-CoA being lower nucleocytosolic,limits the synthesis of fatty acids,acetylation of histone or other processes that is growth related in such energy scarce condition's.