7.2 Bacterial basics II

Question 1

What are obligate aerobes/anaerobes, facultative aerobes, microaeophiles, and aerotolerant anaerobes?

Answer 1

Obligate aerobes
Need oxygen to grow –> Cellular respiration –> Use O2 to oxidize substrates (i.e. sugars & fat) –> generate energy
Facultative anaerobes
Use O2 if it is available
Also can produce energy if O2 is not in the environment
Microaerophiles
Require O2 for energy, but are harmed by atmospheric concentration of O2 (i.e. 21% O2)
Aerotolerant anaerobes
Do not use oxygen but are not harmed by it
Obligate or Strict anaerobes
Harmed by the presence of oxygen

Question 2

Describe the bacterial ribosome

Answer 2

70s

50s, 30s subunits

Question 3

What are the 3 binding sites on the ribosome? What binds to each?

Answer 3

A,P,E
A: tRNA + AA (aminoacyl-tRNA)
P: Where growing peptide chain lives
E- Exit

Question 4

What is THF? Why is it important?

Answer 4

Required essential cofactor for development of deoxynucleotides.

Question 5

How is THF synthesized?

Answer 5

Several step process, inhibited by bactrim

Question 6

What does DNA polymerase do?

Answer 6

responsible for replicating the bacterial chromosome

Question 7

What does topoisomerase do?

Answer 7

egulate twisting or supercoiling of DNA. Regulation involves either add or remove supercoiling of the DNA.
= stabilize DNA while copied

Question 8

What is the difference between bacteriostatic and bactericidal?

Answer 8

Bactericidal – kill bacteria
Bacteriostatic – suppress bacterial growth

Bacteriostatic- more related to protein synthesis/DNA synthesis= don’t kill bacteria right away, just slow growth
Bactericidal- Damage cells wall lysis

Question 9

What are the MIC/MBC?

Answer 9

MIC: Minimum Inhibitory Concentration- minimum concentration of antibiotic that is able to suppress growth of the bacterial isolate.

MBC- Minimum Bactericidal Concentration- minimum concentration of antibiotic that results in killing of the bacterial isolate.

Question 10

What is the Kirby-Bauer Method?

Answer 10

Test for MIC-
Based on the size of zones of inhibition of growth around disks impregnated with the antimicrobial drug
Measurement of the diameter of the zone – determine susceptibility
Larger zone – lower MIC

Question 11

What is the eTEST?

Answer 11

Test for MIC- Strip impregnated with varying concentrations of agent placed on agar