<prompt> Odd chain fatty acids can form glucose by which pathway?By forming Propionyl CoABy forming GlycerolAcetyl CoA entering TCA cycleBy Lactic acid formation  <response>: Ans: a By forming Propionyl CoARef: Harper, Illustrated Biochemistry, 30th edition, Page 225, 558; Styer Biochemistry, 7th edition, Page 650Fatty acids with an odd number of carbon atoms are oxidized by the pathway of 3-oxidation, producing acetyl CoA 2C until a three-carbon propionyl-CoA residue remains.End product of even chain FA oxidation-acetyl CoA2C.End product of odd chain FA oxidation-acetyl CoA units 1 propionyl CoA3C.Propionyl CoA is converted to succinyl-CoA steps mentioned below, a constituent of the citric acid cycle, which after few steps, enters in to gluconeogenesis.Only 2 enzymes in our body requires vit B as cofactor:Methyl malonyl CoA mutase AKA methylmalonyl-CoA isomerase.Methionine synthase Synthesis of Methionine by methylation of homocysteine.Hence, the propionyl residue from an odd-chain fatty acid is the only part of a fatty acid that is glucogenic.Even chain fatty acids cannot synthesize glucose, because PDH reaction is irreversible.Gluconeogenesis is glucose synthesized from non-carbohydrate sources like lactate, propionyl CoA and Glucogenic amino acids. So glucose derived from glycogen break down carbohydrate source is NOT gluconeogenesis. 