exam questions

• explain why antibacterial processes are inhibited in humans and not bacteria (1)

  -       antibiotics block specific processes that occur within prokaryotic cells but not eukaryotic cells 

  -       antibiotics are targeted to interact with prokaryotic cells and bacteria are prokaryotic
• a bactetiostatic antibiotics works by(1) 

  -       preventing the multiplication of bacteria
• explain why bacteriostatic antibiotics could affect the production of proteins in the bacteria (3)

  -       ribosome shape is altered

  -       MRNA is prevented from binding to the ribosome/ causes change in TRNA binding

  -       Therefore, translation cannot occur

  -       Protein/polypeptide is not synthesised
• These new antibiotics attach to a site on the ribosome not affected by any known antibiotics. Deduce why these new antibiotics might be used to treat bacteria that are resistant to other antibiotics (2)

  -       Bacteria have not been exposed to new antibiotics before

  -       Bacteria have developed resistance to other antibiotics by evolving/natural selection

  Thus, there is no mutation present to give resistance
• Devise a laboratory procedure to compare the effectiveness of penicillin with one of the new antibiotics (6)

  -        prepare agar plates with bacterial cultures 

  -        prepare solutions of new antibiotics and penicillin 

  -        place onto paper discs

  -        control time and temperature of incubation (27 degrees)

  -        same conc and volume of both antibiotics

  -        measure the area of inhibition

  -        repeat

  -        statistical test to determine which is most effective.
• State what is meant by the term bacteriostatic antibiotic (1)

  -        a substance which can inhibit growth/prevent multiplication of bacteria