**De Novo Purine Biosynthesis Pathway**De novo purine biosynthesis is a 10-step pathway that constructs the purine rings by adding one atom, or one group of atoms, at a time. The pathway converts 5-phosphoribosyl-1-pyrophosphate (PRPP) to inosine monophosphate (IMP).**Pathway Overview:**1. **5-Phosphoribosyl-1-amine** - Formation from PRPP and amine group addition. 2. **Glycinamide Ribonucleotide** - Glycine is added to the structure. 3. **Formylglycinamide Ribonucleotide** - Formyl group is transferred, utilizing formyl-THF (tetrahydrofolate).4. **Formylglycinamidine Ribonucleotide** - Amidine group addition.5. **5-Aminoimidazole Ribonucleotide** - Cyclization of the imidazole ring.6. **5-Aminoimidazole-4-carboxamide Ribonucleotide** - Carboxylation occurs.7. **N-Succinyl-5-aminoimidazole-4-carboxamide Ribonucleotide** - Aspartate addition, forming a succinyl group bond.8. **Carboxyaminoimidazole Ribonucleotide** - Cyclization and reduction over multiple steps.9. **Inosine Monophosphate (IMP)** - Final purine structure achieved.**Diagram Explanation:**The diagram outlines the sequential steps of de novo purine synthesis, showing structural formulas of intermediate compounds, and chemical reactions involved in transforming PRPP into IMP. The transformations include several additions and modifications of amino groups, carboxylations, and ring closures leading to the complete purine nucleotide.**Answer Bank:**- Space for listing intermediates and possibly filling in missing names or identifying structures.

Nucleotides are building blocks of nucleotides. It consists of a nitrogenous base linked to 1' carbon of a pentose phosphate. The nitrogenous base found in nucleotides can either be a purine (2 heterocyclic rings) or a pyrimidine (1 heterocyclic ring). There are two pathways of biosynthesis of purines: the de novo (from scratch) and the salvage pathway. In the De Novo pathway, the heterocyclic structure is assembled from precursors: phosphoribosylamine, glycine, formate, glutamine, aspartate and carbon dioxideGiven below are the steps of the denovo biosynthesis pathway of purine. 5-phosphoribosyl 1-pyrophosphate (PRPP) + glutamine →glutamine-PRPP amidotransferase 5-phospho-beta-D-ribosylamine 5-phospho-beta-D-ribosylamine + Glycine +ATP →GAR synthaseGlycinamide ribonucleotide (GAR) GAR + formyl-THF→GAR transformylaseFormylglycinamide ribonucleotide (FGAR) FGAR + ATP + Glutamine →FGAR amidotransferaseFormylglycinamidine ribonucleotide (FGAM) FGAM + ATP →FGAM cyclase or AIR synthase5-aminoimidazole ribonucleotide (AIR) AIR + HCO3 + ATP→N5 CAIR synthaseN5-carboxyaminoimidazole ribonucleotide (N5-CAIR) N5-CAIR →N5 CAIR mutaseCarboxyaminoimidazole ribonucleotide (CAIR) CAIR + Aspartate + ATP →SAICAR synthetaseN-succinyl-5-aminoimidazole-4-carboxamide ribonucleotide (SAICAR) SAICAR + Fumarate →SAICAR lyase5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) AICAR + formyl-THF →AICAR transformylase N-formylaminoimidazole-4-carboxamide ribonucleotide (FAICAR) FAICAR →IMP synthaseInosinate (IMP) The mistake is in the reactions catalysed by FGAR amidotransferase. The substrate for the reaction is FGAR and the product is FGAM not SAICAR. And, CAIR is converted to SAICAR by SAICAR synthase. These intermediates have been wrongly labelled.