biol 251 lab 8
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Horizontal gene transfer
happens within the same generation Via pilus
Vertical gene transfer
from parent to offspring
what is the different between F+ and F -?
- F+ has a ampicillin resistance gene in the plasmid
- F- has Streptomycin resistance gene in Chromosome
Bacteria: Strain I resistant to streptomycin (Strep)
Bacteria: Strain II resistance to ampicillin (amp)
Bacteria: M (mix strain) amp and strept
Media: 1) MB, 2) MB+strep, 3) MB+amp, 4) MB+strep & amp.
Which bacteria will be able to withstand the antibiotic in each media?
- 1) I, II, M
- 2) I,M
- 3) II,M
- 4) M
A chemical that either inhibit or kill bacteria
Natural antibiotics (ABX)
Found in the environment. EX: penicillin found in mold
Semi synthetic Antibiotics
What advantage it has over natural antibiotics?
- Similar to natural antibiotic (ABX) with slightly modified R group.
- It increase the bacterial group that the natural antibiotic will target specially those bacteria that resistant to natural antibiotics.
Manufactured in lab
What is the different between bacteriocidal and bacteriostatic antibiotics
- Bacteriocidal: kill bacteria
- Bacteriostatic: inhibit bacteria (growth)
What is the advantage of bacteriostatic over bacteriocidal?
- Bacteriostatic will inhibit bacteria growth allow our natural immune system take care of the rest of the bacteria.
- Bacteriocidal will kill the bacteria along with our natural body flora.
Narrow spectrum vs. broad spectrum
- Narrow spectrum: kill/inhibit one or few types of bacteria
- Broad spectrum: kill/inhibit all bacteria
Which are the different ways that antibiotics may work?
Inhibit synthesis of DNA, proteins, and folic-acid
What did we test in Kirby Bauer experiment?
Resistance or susceptibility of bacteria to different antibiotics.
Which media is standard use for Kirby Bauer test? What is its pH level? What is its thickness?
- Mueller-Hinton II agar.
- pH level: 7.2-7.4
- Thickness: 4 mm
What are the standards for bacteria in Kirby Bauer test?
- Grown over night about 107 cells per μL.
- Use the same amount for each plate
- Lawn (spread out evenly across the plate)
What are the standards for the antibiotics in Kirby Bauer test?
- Must be same amount per disc
- Must be stored correctly
- must be labeled
What are the standards for the preparation the plate in Kirby Bauer test?
- Incubate for 18 hours
What genera of bacteria form endospores?
What allow bacteria to withstand UV radiation?
- SOS system (repair DNA)
What would you like to do?
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