The pathway for synthesis of inosine monophosphate (IMP), the parent purine nucleotide, is described below:

Site of Synthesis Liver is the major site for purine nucleotide synthesis. Erythrocytes, polymorphonuclear leukocytes, and brain cannot produce purines.

Human and most other vertebrates can synthesis some amount of purine and pyrimidine nucleotides de novo (i.e. from amphibolic intermediates)

SECTION A

The ketone body formation (particularly overproduction) occurs primarily due to non-availability of carbohydrates to the tissues. This is an outcome of excessive utilisation of fatty acids to meet the energy requirements of cells. Hormones glucagon stimulates ketogenesis, whereas insulin inhibits. The increased ratio of glucagon/insulin in diabetes mellitus promotes ketone body formation. This is due…

The synthesis of ketone bodies occurs in the liver. The enzymes for ketone bodies synthesis are located in the mitochondrial matrix. Acetyl-CoA formed by oxidation of fatty acids, pyruvate, or some amino acids is the precursor for ketone bodies; ketogenesis occurs through the following reactions:

The compounds namely acetone, acetoacetate, and β-hydroxy butyrate (3-hydroxy butyrate) are known as ketone bodies. Only the first two are true ketone bodies, and β-hydroxy butyrate does not possess a keto group (C=O). Ketones are water soluble and energy yielding.