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5 Written Questions

5 Matching Questions

  1. Ribonucleotide Reductase allosteric effects
  2. how 5 fluorouracil FUra works
  3. Sites of feedback regulation of Purine biosynthesis
  4. How to take Ribonucleosides from Mono, Di and tri phosphate
  5. Gout
  1. a ATP and GTP allosterically inhibit formation of PRPP from pentose phosphate pathway

    IMP, AMP and GMP allosterically inhibit PRPP amidotransferase, the committed step of the pathway with adds a N from Glutamine to PRPP

    AMP and GMP allosterically inhibit the first step in their own formation from IMP

    ATP and GTP are require for each others formation a non-allosteric type of biofeedback
  2. b Elevated levels of Uric Acid, chronic elevation of blood uric acid, hyperuricemia from xanthine overproduction and formation of uric acid

    Also called Gouty arthritis and uric acid nephrophathy

    Uric acid has limited water solubility and precipitates under acidic conditions like collecting ducts eg kidney stones, a can lead to sodium urate that is most likely to precipitate at neutral pH synovial fluid of jointe eg gouty arthritis
  3. c it is similar to dUMP and acts as a suicide inhibitor or thymidylate synthetase TS. This kill rapidly dividing cells Tumors and immune cells
  4. d 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
  5. e Ribonucleotide Reductase is a heterotatramer with 2 types of subunits

    There are 3 types of binding sites

    C= Catalytic site which binds to substrates A, U, G, CDP

    A= Activity Site, for allosterica regulation, this site regulates whether it is fast or slow. I only binds with ATP or dATP to slow the catalytic rate, high dATP is the stop signal

    S= Specificity Site for Allosteric regulation it binds
    -ATP or dATP to activate reduction of CDP and UDP
    -dTTP to activate reduction of GDP and inhibit production of CDP and UDP
    -dGTP to activate reduction of ADP and inhibit reduction of CDP and UDP

5 Multiple Choice Questions

  1. Thymidylate Synthetase uses N5N10 Methylene THF as a methyl transfer group to turn dUMP to dTMP, then becomes DHF which must be recycled
  2. Purine 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
  3. Committed Step, and an allosteric enzyme

    Using Aspartate Transcarbamoylase, ATCase takes Carbamoyl Phosphate to N-carbamoyl aspartate adding aspartate
  4. Used for degradation

    Purine Nucleoside Phosphorylase has multiple substrates. Has a stronger affinity for Guo and Ino, and weak affinity for Ado, all are not phosphorylated

    It takes them all to Guanine, hypoxanthine, and adenine pluse a ribose 1 phosphate
  5. Familial 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 True/False Questions

  1. Phophoribosyl transferases PRTsthis is a way to use biofeedback high GTP means AMP should be formed Low GTP means GMP should be formed


  2. Anti neoplasticssome discussed earlier
    araC, triphosphate interferes with DNA synthesis


  3. Origins of Pyrimidine Ring AtomsN1, C4,5,6= all from Aspartate
    C2, N3 = all from Carbamoyl phosphate


  4. Fifth step in Pyrimidine biosynth OPRTOPRT takes orotate and PRPP and adds ribose P to make OMP


  5. Results of tx with allopurinalAllopurinol is a suicide inhibitor of xanthine oxidase, because it is similar in configuration to hypoxanthine and it binds tightly to molybdenum in xanthine oxidase.

    Xanthine oxidase takes Hypoxanthine to xanthine and xanthine to uric acid


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