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5 Written questions

5 Matching questions

  1. Deoxyribonucleotide dNTP biosynthesis
  2. Sixth step OMP decarboxylase
  3. Anti neoplastics
  4. Purine Biosynthesis Overview
  5. Purine Nucleosid Phosphorylase PNP deficiency
  1. a another rare cause of SCIDS Disorder, since Ino, dIno, Guo and dGuo are strong subtrates of PNP and Ado and dAdo is weak we get a larger build up of dAdo relative to dNTPs
  2. b Removes CO2 and forms Uracil base on ribose P, UMP from OMP
  3. c Uses Ribonucleotide Reductase to take A,G,C,UDP to dA,dG,dC,dUDP

    All can form to triphosphate form easily

    Formation of dTMP and dTTP requires Thymidylate Synthetase, which is dependent on THF cycle and dihydrofolate reductase.
  4. d Starting point with PRPP, and activated ribose

    Purine ring is built up step by step while attached to ribose sugar

    forming IMP a nucleotide intermediate that can form either AMP or GMP
  5. e some discussed earlier
    araC, triphosphate interferes with DNA synthesis

5 Multiple choice questions

  1. Adenylate Kinase takes ATP and AMP to 2 ADPs

    nucleoside monophosphate kinases take G,C,UMPs plus ATP to ADP plus G,C,UDPs

    nucleoside diphosphate kinases take G,C,UDPs plus ATP to ADP plus G,C,UTPs

    oxidative phosphorylation takes ADP plus Pi to ATP
  2. It lowers the PRPP pool by binding and using HGPRT to form an allopurinol ribonucleotide

    This inhibits the action of glutamine PRPP amidotransferase

    and Thus there is less flux through the de novo purine pathway
  3. using Carbamoyl phosphate synthetase II, CPS II takes CO2 and Glutamine to Carbamoyl phosphate using 2 ATP

    In mitochondria CPS I uses NH4+ as a nitrogen source, this is part of the urea cycle
  4. AZT, DDC, ddI
    Used to treat HIV and AIDS
    Triphosphates inhibit retroviral reverse transcriptase
  5. For AMP 8 high energy phosphates, 2 Gln, 1 Gly, 2 Asp

    For GMP 7 high energy phosphates, 3 Gln, 1 Gly, 1 Asp

    Thus we Regulate and use salvage pathways to recycle purines

5 True/False questions

  1. Tx of Gout with Allopurinolserum urate decraeases
    serum hypoxanthine and xanthine increase, these are more soluble and easily excreted
    Decreases total rate of purine biosynthesis


  2. Synthesis fo Thymine NucleotidesThymidylate Synthetase uses N5N10 Methylene THF as a methyl transfer group to turn dUMP to dTMP, then becomes DHF which must be recycled


  3. Primary Genetic basis of GoutPurine biosynthesis regulation and secondary causes

    Increased activity of PRPP synthetase increases conc of PRPP

    Increased activity of PRPP amido transferase

    also Partial loss of activity of HGPRT salvage enzyme


  4. Defects in Pyrimidine BiosynthesisFamilial Orotic Aciduria are inherited deficincies in orotate phosphoribosyltrandferase OPRT and or OMP decarboxylase

    These slow the formation of OMP from orotate, and UMP from OMP.

    Signs and symptomes are growth retardation, megaloblastic anemia, crystalline orotate in urine

    Tx effectively by large doses of orally administered uridine


  5. Results of tx with allopurinalserum urate decraeases
    serum hypoxanthine and xanthine increase, these are more soluble and easily excreted
    Decreases total rate of purine biosynthesis