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5 Written Questions

5 Matching Questions

  1. Glutamine PRPP amido transferase
  2. How to take Ribonucleosides from Mono, Di and tri phosphate
  3. Effects of Allopurinol Tx on LNS pts
  4. how 5 fluorouracil FUra works
  5. Importance of adenosine Deaminase
  1. a it is similar to dUMP and acts as a suicide inhibitor or thymidylate synthetase TS. This kill rapidly dividing cells Tumors and immune cells
  2. b 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
  3. c ADA deaminates Adenosine to insosine, enabling the salvage pathway of HGPRT to take it to IMP. after the ribose and phosphate are removed by PNP

    if ADA does not work SCIDS develops
  4. d The most important step, most difficult thermodynamically, and committed step.

    goes from PRPP to PRA

    Takes nitrogen from Glutamine and places on ribose with a PPi leaving group and Glucose formed
  5. e Reduces 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

5 Multiple Choice Questions

  1. 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
  2. Clinical 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
  3. 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
  4. Allopurinol 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
  5. 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 True/False Questions

  1. Important Enzymes in Pyrimidine BiosynthFamilial 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


  2. Second Step in Pyrimidine biosynth ATCaseCommitted Step, and an allosteric enzyme

    Using Aspartate Transcarbamoylase, ATCase takes Carbamoyl Phosphate to N-carbamoyl aspartate adding aspartate


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

    Fumarate leaves leaving just NH2 and AMP is formed


  4. Prokaryotic Regulation of Pyrimidine BiosynthCTP 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. 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


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