Lecture 26
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Questions and Answers

What is the primary function of the salvage pathway in nucleotide metabolism?

  • To synthesize nucleotides from metabolic precursors
  • To catalyze the breakdown of nucleic acids
  • To recycle the free bases and nucleosides released from nucleic acid breakdown (correct)
  • To regulate the nucleotide pools in the cell

    • What is the common precursor for both purine and pyrimidine nucleotides?

  • PhosphoRibosylPyroPhosphate (PRPP) (correct)
  • Aspartate
  • Glycine
  • Ribose-5-phosphate

    • Which of the following is NOT a precursor for purine nucleotides?

  • CO2
  • Gln
  • Glycine
  • Aspartate (correct)

    • What is the purpose of continually synthesizing nucleotides in cells?

    <p>To regulate the rates of transcription and replication</p> Signup and view all the answers

    Which of the following is a potential treatment for African trypanosomiasis?

    <p>Allopurinol</p> Signup and view all the answers

    What is the origin of the N10 formyl group in purine nucleotides?

    <p>N10 Formyl THF</p> Signup and view all the answers

    Which enzyme is responsible for salvaging free adenine in cells?

    <p>Adenosine PhosphoRibosylTransferase (A-PRT)</p> Signup and view all the answers

    What is the result of a deficiency in Hypoxanthine-Guanine PhosphoRibosylTransferase (HG-PRT)?

    <p>Lesch-Nyhan syndrome</p> Signup and view all the answers

    Which chemotherapeutic agent is a structural analog of tetrahydrofolate?

    <p>Methotrexate</p> Signup and view all the answers

    What is the purpose of administering allopurinol to patients with Lesch-Nyhan syndrome?

    <p>To reduce uric acid production</p> Signup and view all the answers

    What is the product of the reaction catalyzed by Adenosine PhosphoRibosylTransferase (A-PRT)?

    <p>AMP + PPi</p> Signup and view all the answers

    Which of the following is NOT a symptom of Lesch-Nyhan syndrome?

    <p>Purine deficiency</p> Signup and view all the answers

    What is the primary function of nucleotides in energy metabolism?

    <p>To carry chemical energy primarily through ATP and GTP</p> Signup and view all the answers

    What is the significance of increased nucleotides biosynthesis in highly dividing cells?

    <p>It is a characteristic of cancer cells</p> Signup and view all the answers

    What is the role of S-Adenosylmethionine in cellular metabolism?

    <p>It is involved in methyl group transfers</p> Signup and view all the answers

    What is the primary source of nucleotides in de novo biosynthesis?

    <p>Amino acids, ribose-5-phosphate, CO2, and NH3</p> Signup and view all the answers

    What is the role of nucleotides in glycerolipid biosynthesis?

    <p>They are components of CDP-diacylglycerol</p> Signup and view all the answers

    What is the significance of nucleotide analogs in anti-AIDS therapy?

    <p>They are used to inhibit the replication of HIV</p> Signup and view all the answers

    What is the primary mechanism of regulation in de novo purine nucleotide synthesis?

    <p>Feedback inhibition</p> Signup and view all the answers

    Which of the following is NOT a feedback inhibitor of PRPP synthesis?

    <p>AMP</p> Signup and view all the answers

    What is the role of GTP in the synthesis of purine nucleotides?

    <p>Required for the synthesis of AMP</p> Signup and view all the answers

    What is the effect of excess GMP on the formation of xanthylate (XMP)?

    <p>Inhibits the formation of XMP</p> Signup and view all the answers

    What is the committed step of the de novo purine nucleotide synthesis pathway?

    <p>Glutamine-PRPP amidotransferase</p> Signup and view all the answers

    What is the role of ATP in the synthesis of purine nucleotides?

    <p>Required for the synthesis of GMP</p> Signup and view all the answers

    What is the effect of allopurinol on xanthine oxidase?

    <p>It is converted to oxypurinol, a strong competitive inhibitor</p> Signup and view all the answers

    What is the end product of pyrimidine degradation in most organisms?

    <p>Urea</p> Signup and view all the answers

    What is the fate of uric acid in different species?

    <p>It is species-specific</p> Signup and view all the answers

    What is the result of the degradation of thymine?

    <p>Succinyl-CoA</p> Signup and view all the answers

    What is the result of the degradation of CMP and UMP?

    <p>b-alanine</p> Signup and view all the answers

    What is the purpose of withholding food rich in nucleotides and nucleic acids in the treatment of gout?

    <p>To reduce the amount of uric acid produced</p> Signup and view all the answers

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