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5 Written questions

5 Matching questions

  1. Anti neoplastics
  2. Defects in Pyrimidine Biosynthesis
  3. First Step in Pyrimidine biosynth CPS II
  4. Hypoxanthine
  5. Anti retrovirals
  1. a some discussed earlier
    araC, triphosphate interferes with DNA synthesis
  2. b AZT, DDC, ddI
    Used to treat HIV and AIDS
    Triphosphates inhibit retroviral reverse transcriptase
  3. c 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
  4. d the base on IMP
  5. e 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

5 Multiple choice questions

  1. high conc of dATP stops the enzyme and other dNTPs are not made
  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. CTP inhibits two enzymes

    CTPS which forms CTP from UTP is inhibited by CTP, also it requires GTP so low GTP will slow CTP formation

    CPS II is the first reaction which forms carbamoyl P, and is inhibited by CTP
  4. CTP synthetase takes Nitrogen from Glutamine and ATP and makes CTP the base Cytosine with ribose and three phosphates.
  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. Folate antagonists as Antibiotics, Trimethoprimammonia toxicity
    Ornithine transcarbamoylase def
    in both cases carbamoyl P accumulated in liver mitochondria, which enters cytoplasm, which drives overproduction of orotate via the pyrimidine biosynthesis pathway.

          

  2. Importance of adenosine DeaminaseSigns and Symptoms young with hematuria, megaloblastic anemia, hyperuricemia, crystals in urine, mental retardation, decreased gross motor function, and self mutilation, gout in early 20s

    is a Rare X linked disorder 1/400000 males, milder form = 8% kelly-seegmiller syndrome

    Cause = near total deficiency of HGPRT about 2% of activity

    biochemical consequenses
    Overproduction or urate
    Elevated PRPP concentrations
    Marked increase in rate of de novo purine biosynth

          

  3. Effects of Allopurinol Tx on LNS ptsReduces urate in LNS pts by blocking xanthine oxidase rxns

    Ineffective in reducing rate of de novo purine biosynthesis, since it cannot synthesize allopurinol ribonucleotide from allopurinal and PRPP, it requires HGPRT

    Can have neurological effects due to the brains reliace on salvage pathways for most purine nucleotide production and needs GTP for dopamine formation

          

  4. Phophoribosyl transferases PRTsthis is a way to use biofeedback high ATP means GMP should be formed Low ATP means ATP should be formed

          

  5. how 5 fluorouracil FUra worksAZT, DDC, ddI
    Used to treat HIV and AIDS
    Triphosphates inhibit retroviral reverse transcriptase

          

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