L31

Question 1

Name the steps of prokaryotic cell division.

Answer 1

1. Initiated @cytoplasmic membrane
2. Daughter chromosomes anchored to membrane
3. Septum grows & divides daughter cells

Question 2

What causes bacteria remain linked to form chains/clusters?

Answer 2

Incomplete cleavage of septum

Question 3

What are obligate aerobes?

Answer 3

Require O2 b/c acts as terminal e- acceptor

Question 4

What are obligate anaerobies?

Answer 4

Energy via fermentation

NO O2

Question 5

What are facultative anaerobes?

Answer 5

Grow w/ or w/o O2 - can do both respiration or fermentation

Generally prefer O2

Question 6

What are microaerophiles?

Answer 6

Can handle low levels O2

Question 7

What are the 2 reasons anaerobes can’t handle O2?

Answer 7

1. Don’t have superoxide dismutase
2. No catalase or peroxidase
   No ways to degrade superoxide or hydrogen peroxide –> stick around and kill anaerobic bacteria

Question 8

What are the 3 classification of bacteria by temperature?

Answer 8

Thermophilic = like hot
Mesophilic = like body temp
Psychrophilic = cold

Question 9

What are the 4 phases of a bacterial growth curve?

Answer 9

Lag phase
Exponential (log) phase
Stationary phase 
- Reproduction = death 
Decline (due toxic byproducts of reproduction)

Question 10

What occurs during the lag phase?

Answer 10

Bacteria:

• Store nutrients
• Synthesize enzymes
• Prepare for binary fission

Question 11

What is the generation time? Give the equation.

Answer 11

Time required for cell # to double
g = t/n
(n = # generations aka # times cell population doubles during the time interval)

Question 12

How do you test generation time?

Answer 12

Pour plate

• Serial dilutions
• Plate & count CFUs

Question 13

Define asepsis.

Answer 13

State of being free of micro-organisms

Question 14

Define sterilization.

Answer 14

Elim ALL viable organisms & spores

Question 15

Define disinfection.

Answer 15

Kill MOST micro-organisms

Question 16

Define sanitization.

Answer 16

Reduce pathogen level

Question 17

Germicide

Answer 17

Kills bacteria & some spore

Question 18

Disinfectant

Answer 18

Kills bacteria, fungi, viruses

Ineffective vs spores

Question 19

Antiseptic

Answer 19

Bacteriostatic

Question 20

What is the hierarchy of resistance of microbes to disinfection?

Answer 20

Least resistant = enveloped viruses (lipo-philic)
Bacteria
Non-envelop/hydrophilic viruses
Mycobacteria
Spores

Question 21

Autoclaving

Answer 21

Pressure + heat + steam

Question 22

What are other disinfection options?

Answer 22

Hot air sterilization 
Filtration disinfection 
Radiation (UV vs ionizing)
Ethylene oxide = sterilization
Alcohol (ethyl & isopropyl)
Halogens (chlorine)

Question 23

What are the options for disinfecting the skin?

Answer 23

Alcohol scrub > soap

EXCEPT C.diff - soap to clean off spores!

Question 24

Describe the 4 main characteristics of a biofilm.

Answer 24

1. Attached to hydrated surface
2. Embedded in polysacc slime
3. Behave as community
4. Antibiotic resistant & can’t be cleared by host immunity

Question 25

Name some biofilm associated diseases.

Answer 25

CF
Endocarditis
Osteomyelitis
Chronic UTI
Prostatitis
Otitis media
Dental infections
Indwelling medical device infections

Question 26

Why are microbes in a biofilm resistant to antibiotics?

Answer 26

Slow growing

Reduce antibiotic penetration

Question 27

What is an issue with attributing an infection to a biofilm?

Answer 27

MIC/MBC inaccurately predict bacterial populations IN SITU

- CFU counts