Ketone bodies are all except-
Ans. is 'd' i.e., Acetyl-CoA o Ketone bodies are acetoacetate, (3-hydroxybotyrate and acetone.o Ketone bodies are synthesized exclusively in liver mitochondriaQ from acety l CoAQ or acetoacetyl CoA; the process is called ketogenesis. Ketogenesis occurs w hen there is a high rate of fatty acid oxidation in liver w hich provides excessive acetyl CoAQ. Ketogenesis involves following steps:-Acetoacetyl-CoA is the starting material for ketogenesis. This can arise in two ways:-Directly during b-oxidation of fatty acids, during last cycle of b-oxidation the starting material is 4 carbon acyl CoA, i.e. acetoacetyl CoA.Two molecules of acetyi-CoAcondense to form acetoacetyl-CoA. This reaction is catalyzed by thiolaseAcetoacetyl-CoA combines with another acetyl CoA molecule to produce 3-hydroxy-3-methylglutaryl CoA (HMG CoA), a reaction catalyzed by HMG-Co.A synthase. This is the rate-limiting step in ketogenesis.HMG-CoA is then cleaved to acetyl-Co.A and acetoacetate by enzyme HMG-Co.A lyase. Thus, HMG-CoA serves as the immediate precursor for acetoacetateQ.Acetoacetate is reduced, by b-hydroxybutyrate dehydrogenase, into b-hydroxy butyrate. A small fraction of acetoacetate undergoes spontaneous decarboxylation to form acetone.
Acetoacetate
Acetone
b-hydroxy butyrate
Acetyl-CoA
Oxidation of Fatty acids: Ketogenesis