← microbiology 5 Test
5 Written Questions
5 Matching Questions
- How do tetracyclines work?
- What is an antimicrobial agent?
- What is solid culture?
- How do macrolides work?
- What are plasmids?
- a extra chromosomal circular pieces of DNA that replicate i bacteria
- b inhibit translation by binding to the small (30S) ribosomal subunit. Tetracylines block binding of aminoacyl-tRNA to the A site of the ribosome. Inhibits growth of almost all gram positive and negative bacteria. Used in treatment of STDs, legionnaire's disease, anthrax
- c inhibit protein synthesis by interacting with large (50s) subunit of the ribosome and blocking peptide bond formation. Examples: erythromycin used in patients who are allergic to penicillin
- d disk diffusion technique. Disk of filter paper is soaked with an antimicrobial agent. Disk then placed onto an agar plate that was previously inoculated with a bacterium. Antimicrobial agent diffuses from the disk onto agar, creating a gradient, further from disk= lower conc of antimicrobial. If microbial= bacteriostatic, bacteriocidal a zone of inhibition results
- e a natural or synthetic compound that kills or prevents growth of bacteria or other microorganisms
5 Multiple Choice Questions
- Kill and lyse bacteria. Toxicity is not reversed by dilution. Examples include antibiotics that inhibit cell wall synthesis.
- An antimicrobial agent produced by a microorganism (natural)
- inhibit cell wall synthesis, bind and inhibit penicillin binding proteins, enzymes that synthesise peptidoglycan. Inhibit the transpeptidation step of cell wall biosynthesis.
- prevents growth of bacteria by inhibiting synthesis of mycolic acid, a cell wall component only found in bacteria. Though to inhibit NAD dependent enzymes involved in mycolic acid synthesis. Used to treat TB
- contain genes encoding proteins that confer antimicrobial resistance, referred to as R plasmids. Can be transmitted from one bacterium to another through genetic exchange (conjugation), thought to be one of the main ways resistance spreads.
5 True/False Questions
What must an antimicrobial do to be clinically useful? → bacteriostatic, bacteriocidal, bacteriolytic
What inactivates penicillin G, amphicillin and carbenicillin? → Organism may be able to alter the to an inactive form. eg enzymatic phosphorylation of streptomycin, degradation of Penicillin G. Usually plasmid encoded.
How do Aminoglycosides work? → Inhibit protein synthesis by targetting the small (30s) subunit of the ribosome (s12) protein. No longer used as bacterial resistance occurs frequently.
Inactivation of antibiotic- resistance? → The organism may lack the structure an antibiotic inhibits, eg mycoplasmids lack a cell wall and are therefore resistant to penicillins
How do Quinolones work? → inhibit protein synthesis by interacting with large (50s) subunit of the ribosome and blocking peptide bond formation. Examples: erythromycin used in patients who are allergic to penicillin