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5 Written questions

5 Matching questions

  1. Important Enzymes in Pyrimidine Biosynth
  2. How Methotrexate Mtx anti folate works
  3. Why IMP to GMP uses ATP
  4. Other drugs related to nucleotides and nucleotide metabolism
  5. Fifth step in Pyrimidine biosynth OPRT
  1. a OPRT takes orotate and PRPP and adds ribose P to make OMP
  2. b rather than directly inhibiting Thymidylate Synthetase TS is inhibits the cyclical production of the methyl donor N5N10 methylene THF

    It does this by inhibiting the enzyme DHFR dihydrofolate reductase. Stopping the reduction of Dihydrofolate to THF, which is a needed substrate for N5N10 methylene THF
  3. c Antivirals, acyclovir, Arabinosyladenine araA, for HSV and herpes related viral encephalitis
    Anti retrovirals, AZT, DDC, ddI for HIV
    Anti neoplastics, arabinosylcytosine araC
    Anti Leukemics, 6 mercaptopurin, 6 thiaguanine
  4. d CPS II = takes CO2 and Gln to Carbamoyl P
    ATCase, committed step = take Carbamoyl P and Aspartate to N-Carbamoyl aspartate
    CTPS = takes UTP to CTP
  5. e this is a way to use biofeedback high ATP means GMP should be formed Low ATP means ATP should be formed

5 Multiple choice questions

  1. the base on IMP
  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. 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
  4. 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
  5. SCIDS is an Adenosine Deaminase ADA deficiency

    boy in the bubble syndrome, failure of both B and T lymphocytes to proliferate

    all forms inherited, half result from absence of ADA encoded on chromosome 20

    First target for human gene therapy

5 True/False questions

  1. Common threadClinical use of nucleotide analogs usually is restricted to bases and nucleoside since phosphorylated nucleotides are poorly transported into cells

    They rely on tricking cellular or viral enzymes into phosphorylating nucleosides into metabolically active nucleotide forms, or converting bases into nucleotides vis salvage pathways


  2. Third step in Pyrimidine biosynth DihydroorotaseCTP synthetase takes Nitrogen from Glutamine and ATP and makes CTP the base Cytosine with ribose and three phosphates.


  3. Purine Biosynthesis IMP to GMPIMP uses Aspartate and GTP to add N in place of carboxyl O at top

    Fumarate leaves leaving just NH2 and AMP is formed


  4. Sites of feedback regulation of Purine biosynthesisCTP inhibits the action of ATCase the committed step and addition of aspartate to carbamoyl P

    and UMP inhibits the action of CPSII the first step and formation of Carbamoyl p


  5. Pyrimidine Synthesis Differences from PurinesUnbranched pathway
    Pyrimidine ring synthesized first then attached to ribose phosphate


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