ch 19

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BrigittaLis
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75442
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ch 19
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2011-03-27 10:16:13
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ch 19
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  1. Which antibiotics come from streptomyces bacteria?
    • - Amphotericin B
    • - Chloramphenicol
    • - Erythromycin
    • - Kanamycin
    • - Neomycin
    • - Nystatin
    • - Rifampin
    • - Streptomycin
    • - Tetracyclines
    • - Vancomycin
  2. Which antibiotic comes from micromonospora bacteria?
    - Gentamicin
  3. Which antibiotics come from bacillus bacteria?
    • - Bacitracin
    • - Polymyxins
  4. Which antibiotics come from penicillium fungi?
    • - Griseofulvin
    • - Penicillin
  5. Which antibiotic comes from cephalosporium bacteia?
    - Cephalosporins
  6. What is the difference between broad range and narrow range antibiotics?
    • Broad: Can work on bacteria from both gram-positive and gram-negative groups
    • Narrow: Restricted to either gram-positive, or gram-negative, works for one, ineffective against the other
    • Can you hit alot of bacteria with one antibiotic?If yes, broad, if no, narrow. If you know exactly what type of bacteria is infecting you, you want as narrow spectrum of an antibiotic as you can get. (If you don’t know what is causing the infection, broad spectrum antibiotics are more likely to do the trick but will also kill bacteria that don’t need to be killed)
  7. What was the first antibiotic discovered?
    Penicillin, Alexander Fleming was working with Staph aureus in 1828 and accidentally allowed the fungus penicillium to contaminate his plate. He saw that the staph wasn’t growing where the fungi was growing.
  8. How do antibiotics inhibit the bacterial cell wall?
    • - Most appealing b/c it’s found in bacteria but not humans.
    • - The activity of cell
    • -wall growth inhibiting antibiotics is most effective during active growth of bacteria while new cell wall is being built.
    • - Penicillin, cephalosporins, and carbapenems all work by inhibiting the growth of bacterial cell wall
  9. How do antibitoics inhibit the bacterial plasma membrane?
    - The plasma membrane in bacteria is involved with membrane transport, DNA replication, the production of ATP, and other important physiological functions. It is therefore a prime target for antibiotics because any disruption of this membrane will destroy the bacteria’s ability to survive
  10. How do antibiotics affect synthesis of bacterial proteins?
    • Aminoglycosides: change 30S subunit of ribosome shape so mRNA is misread
    • Tetracycline: Blocks ribosome docking site of tRNA
    • Chloramphenicol: Inhibits peptide bond formation
    • Macrolide: Binds 50S subunit and prevents mRNA moving through ribosome
  11. How do antibiotic affect bacterial nucleic acids?
    • Quinolones: Block either DNA replication or DNA repair.
    • Rifamycins: Were originally isolated from Streptomyces. These antibitoics bind to the RNA polymerase molecule and disrupt its three-dimensional shape, rendering the polymerase molecule unable to function properly.
  12. Understand how penicillin and chloramphenicol work to inhibit cell wall synthesis
    • Penicillin blocks cross links, the enzyme
    • Chloramphenicol: affects cell wall on outside of cell wall, blocks transport of NAG and NAM molecules from inside to outside of cell. So cell wall is expanding but there are no new NAG or NAM molecules to fill in cell wall expansion, so cell dies.
  13. Which have the most antibiotics that can be used against it for treatment? Bacteria, fungi, or viruse?
    There are more antibiotics available to treat bacteria than there are fungal infections, and more to treat fungal infections than viruses (antibiotics don’t work against viruses, so there are none)
    • This figure shows the metabolic pathway used to generate nucleic acids. ONe of the intermediates in this pathway is para-aminobenzoic acid (PABA).
    • Panal a: shows that sulfa drugs can inhibit this pathwya
    • Panal b: Illustrates the reason for this blockade.
    • Notice how the strucutre of sulfa drugs is very similar to the PABA molecule and will competitively inhibit the pathway

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