MCQ Book Questions

Q51660. The major determinant of the overall rate of denovo purine nucleotide biosynthesis is the concentration of

Q51661. An enzyme which acts as allosteric reg- ulator and sensitive to both phosphate concentration and to the purine nucle- otides is

Q51662. PRPP glutamyl amidotransferase, the first enzyme uniquely committed to purine synthesis is feed back inhibited by

Q51663. Conversion of formylglycinamide ribosyl- 5-phosphate to formyl-glycinamide ribosyl-5-phosphate is inhibited by

Q51664. In the biosynthesis of purine nucleotides the AMP feed back regulates

Q51665. 6-Mercapto purine inhibits the conversion of

Q51666. Purine biosynthesis is inhibited by

Q51667. Pyrimidine and purine nucleoside bio- synthesis share a common precursor:

Q51668. Pyrimidine biosynthesis begins with the formation from glutamine, ATP and CO2, of

Q51669. The two nitrogen of the pyrimidine ring are contributed by

Q51670. A cofactor in the conversion of dihydro- orotate to orotic acid, catalysed by the enzyme dihydroorotate dehydrogena- se is

Q51671. The first true pyrimidine ribonucleotide synthesized is

Q51672. UDP and UTP are formed by phosphory- lation from

Q51673. Reduction of ribonucleotide diphosphates (NDPs) to their corresponding deoxy ribonucleotide diphosphates (dNDPs) involves

Q51674. Conversion of deoxyuridine monophos- phate to thymidine monophosphate is catalysed by the enzyme:

Q51675. d-UMP is converted to TMP by

Q51676. UTP is converted to CTP by

Q51677. Methotrexate blocks the synthesis of thymidine monophosphate by inhibiting the activity of the enzyme:

Q51678. A substrate for enzymes of pyrimidine nucleotide biosynthesis is

Q51679. An enzyme of pyrimidine nucleotide bio- synthesis sensitive to allosteric regulation is