Antibiotics Resistance Mechanisms Quiz
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Questions and Answers

How do tetracyclines achieve selective toxicity towards bacteria?

  • By entering mammalian cells with lower affinities
  • By requiring magnesium ions for their binding at the ribosomal site
  • By preventing aminoacyl tRNA binding to the mRNA-ribosome complex
  • By concentrating within bacterial cells due to an active uptake process (correct)
  • What is the mechanism behind ribosomal protection in bacteria against tetracyclines?

  • Increasing the bacterial cell self-destructive capacity
  • Reducing intracellular tetracycline concentration
  • Inhibiting enzymatic oxidation
  • Rendering the bacterial protein synthesis apparatus resistant (correct)
  • Why do tetracyclines have selective toxicity towards bacteria?

  • Because bacterial cells concentrate tetracyclines internally (correct)
  • As a result of passive diffusion into bacterial cells
  • Due to higher affinities for mammalian ribosomes
  • Because of their inhibitory effect on enzymatic oxidation
  • What is the role of magnesium ions in the mechanism of action of tetracyclines?

    <p>Enhancing the affinity of tetracyclines for bacterial ribosomes</p> Signup and view all the answers

    How do tetracyclines enter bacterial cells?

    <p>Via active transport requiring ATP and magnesium ions</p> Signup and view all the answers

    What is a key characteristic of the mechanism of action of macrolides?

    <p>Binding to the 30S ribosomal subunit and blocking aminoacyl tRNA binding</p> Signup and view all the answers

    What is the mechanism of action of macrolide antibiotics like erythromycin, clarithromycin, and azithromycin?

    <p>They inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit.</p> Signup and view all the answers

    What structural feature of macrolide antibiotics contributes to their acid stability?

    <p>The 3-keto function.</p> Signup and view all the answers

    Which of the following is a key structural modification that was made to macrolide antibiotics to improve their pharmacokinetics and pharmacodynamics?

    <p>Introducing a 6-methoxy, 6-alkylaryl substituent.</p> Signup and view all the answers

    Which of the following is a key advantage of azithromycin over erythromycin?

    <p>Azithromycin has a broader spectrum of antibacterial activity.</p> Signup and view all the answers

    What is a key advantage of clarithromycin over erythromycin?

    <p>Clarithromycin is more stable in gastric acid and causes less GI irritation.</p> Signup and view all the answers

    What is a key structural feature of macrolide antibiotics that helps overcome erythromycin resistance?

    <p>The 3-keto function.</p> Signup and view all the answers

    Which of the following statements accurately describes the mechanism of action of protein synthesis inhibitors?

    <p>They bind to the protein portion of the 30S ribosomal subunit, leading to the mistranslation of RNA templates and the insertion of wrong amino acids.</p> Signup and view all the answers

    Which of the following statements accurately describes the selectivity of aminoglycoside antibiotics?

    <p>They bind specifically to the 30S and 50S subunits of prokaryotic ribosomes, but not to eukaryotic ribosomes.</p> Signup and view all the answers

    Which of the following aminoglycoside antibiotics is primarily used in the treatment of tuberculosis?

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

    Which structural feature of aminoglycosides is particularly important for their antibacterial activity?

    <p>The presence of amino functions at the 6' and 2' positions.</p> Signup and view all the answers

    Which of the following statements accurately describes the structure-activity relationship (SAR) of aminoglycosides?

    <p>Methylation at the 6-carbon or 6-amino positions does not appreciably lower antibacterial activity and confers resistance to enzymatic acetylation.</p> Signup and view all the answers

    Which of the following classes of antibiotics also inhibits protein synthesis by binding to ribosomes?

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

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