Antibiotics Resistance Mechanisms Quiz

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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?

Enhancing the affinity of tetracyclines for bacterial ribosomes (B) Signup and view all the answers

How do tetracyclines enter bacterial cells?

Via active transport requiring ATP and magnesium ions (C) Signup and view all the answers

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

Binding to the 30S ribosomal subunit and blocking aminoacyl tRNA binding (A) Signup and view all the answers

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

They inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit. (C) Signup and view all the answers

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

The 3-keto function. (C) 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?

Introducing a 6-methoxy, 6-alkylaryl substituent. (D) Signup and view all the answers

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

Azithromycin has a broader spectrum of antibacterial activity. (D) Signup and view all the answers

What is a key advantage of clarithromycin over erythromycin?

Clarithromycin is more stable in gastric acid and causes less GI irritation. (B) Signup and view all the answers

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

The 3-keto function. (C) Signup and view all the answers

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

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. (A) Signup and view all the answers

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

They bind specifically to the 30S and 50S subunits of prokaryotic ribosomes, but not to eukaryotic ribosomes. (A) Signup and view all the answers

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

Streptomycin (B) Signup and view all the answers

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

The presence of amino functions at the 6' and 2' positions. (C) Signup and view all the answers

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

Methylation at the 6-carbon or 6-amino positions does not appreciably lower antibacterial activity and confers resistance to enzymatic acetylation. (A) Signup and view all the answers

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

Tetracyclines (B) Signup and view all the answers