Quiz 5

Question 1

β-lactams

Answer 1

Penicillins - Penicillium spp.

Cephalosporins - Cephalosporium spp.

Inhibit peptidoglycan synthesis

Question 2

Macrolides

Answer 2

Erythromycin - Streptomyces erythreus

Inhibit 50S rRNA

Question 3

Aminoglycosides

Answer 3

Streptomycin - S. griseus

Neomycin - S. fradiae

Gentamicin - Micromonospora purpurea

Inhibit 30S rRNA

Question 4

Tetracyclines

Answer 4

Tetracycline - S. aureofaciens

Inhibit aminoacyl-tRNA binding to ribosomes during translation

Question 5

What two strains were swabbed onto yeast-malt agar plates in Ex 12?

What bacteria were streaked to test resistance?

Answer 5

• Penicillium notatum*
• Streptomyces griseus*
• Escherichia coli, Bacillus sibtilis, Staphylococcus aureus* (penicillin-sensitive), Micrococcus luteus

Question 6

MacFarland standard

Answer 6

A standard measure of turbidity used to estimate cell count. .5 MacFarlands is approximately equal to 10⁸ CFU/mL

Question 7

MIC

Answer 7

Minimum inhibitory concentration (MIC)

The lowest amount of antibiotic that will prevent growth

Proportional to the diameter of the inhibitory region

Question 8

What are the four zones on plasmid pBBR1MCS-2

Answer 8

• Kan* (kanamycin resistance)
• mob* (mobilisation)
• rep* (origin of replication)
• lacZ* (β-galactosidease), which contains the restriction site called the multiple cloning site (MCS)