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microbiology exam 2 > micro exam 2 > Flashcards

micro exam 2 Flashcards

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1
Q

sterilization

A

complete killing of all organisms
heat, radiation, chemicals,
once it is sterilized, it will stay that way if properly sealed
easier to kill at an acidic ph

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2
Q

methods of sterilizaton

A

autoclave, filter sterilization, cold sterilization, pasteurization

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3
Q

autoclave

A

high pressure, high temperature, moist environment
like a pressure cooker
has a valve that is turned to get it to above the boiling point
it is not the pressure that kills, but the high temperature
121 degrees C, 15 mins (250 degrees f)
the length of time depends on how much is on the autoclave

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4
Q

filter sterilization

A

used for heat sensitive solutions like vitamins and antibiotics
allows liquid to pass through, leaving the bacteria and viruses behind
nucleation track-uniform holes
0.2um - complete sterilization
0.45um- only small viruses can pass through

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5
Q

cold sterilization

A

used for surgical instruments

enclosed environment with hydrogen peroxide, ozone, formaldehyde

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6
Q

pasteurization

A

not complete sterilization but to avoid food spoilage
reduce the amount of pathogenic bacteria
temperature is quickly raised to 71.6 degrees f, 15 secs and quickly cooled (flash pasteurization)

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7
Q

antimicrobial agent

A

chemically made or a natural product that kills or inhibits bacterial growth

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8
Q

selective toxicity

A

some agents kill bacteria better than animal tissue

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9
Q

minimum inhibitory concentration

A

smallest amount needed to inhibit the growth of an organism

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10
Q

tube dilution technique

A

serial dilutions of reagent to be tested
inoculate with test organism
after incubation, look for the lowest concentration of reagent where cells don’t grow

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11
Q

agar diffusion technique or Kirby-Bauer Method

A

agents diffuse from the disc, setting up a concentration gradient
the closer to the disc, the higher the concentration of reagent
At conc greater than or equal to the MIC- no growth
less than MIC -growth

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12
Q

zone of inhibition

A

clear zone around a disc
the bigger the zone, the more sensitive the organism is to the reagent on the disc
the smaller the zone, the more resistant the organism is to the reagent on the disc

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13
Q

what chemicals are taken internally and which ones are externally?

A

Germicides are externally

Chemotherapeutic agents are internally

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14
Q

germicides

A

used in situations where it is not practice to sue heat for sterilization
don’t always completely sterilize but just reduce the number of organisms in the area

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15
Q

disinfectants

A

chemicals that kill microbes are used on inanimate objects

Lysol, Bleach

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16
Q

antiseptics

A

chemicals that kill microbes are safe to use on living cells

Listerine, rubbing alcohol

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17
Q

chemotherapeutic agents

A

control microbial growth in the body
select toxicity is important
interfere with bacterial growth processes

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18
Q

sulfa drugs

A

sulfanilamide - analog of p-aminobenzoic acid (intermediate in the folic acid pathway)
works against bacteria (make their own folic acid) but not against animals (from their diet)

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19
Q

flourouracil

A

uracil analog;

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20
Q

bromouracil

A

thymine analog

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21
Q

antibiotics

A

produced by bacteria (and some fungi) that act against other bacteria
ex: penicillin
inhibit cell wall synthesis, disruption of cell membrane function, inhibition of protein synthesis, inhibition of nucleic acid synthesis, and action as antimetabolites

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22
Q

narrow spectrum

A

only target few kinds of bacteria

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23
Q

broad spectrum

A

work on many different kinds of organisms

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24
Q

societal causes of antibiotic resistance

A
  1. overprescribed by doctors

2. patients fail to take the full prescription

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25
biological mechanisms of antibiotic resistance
1. organism lacks structure that antibiotic inhibits (penicillin inhibit cell wall structure and if no cell wall, it doesn't work) 2. organism is impermeable to the antibiotic (antibiotic cannot get inside the cell, not do anything) 3. organism alters antibiotic to an inactive form (treatment for gonorrhea, the organisms were producing enzyme to destroy the antibiotic) 4. organism modifies target of an antibiotic (not acting on antibiotic but the target cell, tetracycline resistant strains have a mutation in the ribosomes so it cannot bind to the protein) 5. organism can pump antibiotic out of cell (target lots of antibiotics) 6. genetic alteration occurs in metabolic pathway in which the antimicrobial agent blocks (sulfanilamide, the reaction pathway was changed and instead of starting with A, it started with B, the sulfanilamide wont work.
26
prophylactic antibiotics in farming
crowd animals together and the chickens, as long the lights are on, they found the chickens eat. the chicken litter is fed to the cattle, and then their bacteria become resistant to the antibiotic.
27
antibacterial chemicals in soaps and cleaning products
plain soap and water without the compounds added work just as well to remove microorganisms
28
culture
growing population of bacteria | "cloudy"
29
pure culture
contains only 1 type of microorganism
30
contaminants
unwanted organisms present in a culture
31
culture medium (media)
needs a carbon and energy source | can be chemically defined or undefined
32
chemically defined
making a cake from scratch; all the ingredients are known!
33
chemically undefined
like making a cake from a cake mix; ingredients vary from batch to batch
34
selective
promotes the growth of one organism; inhibits the growth of others ex: m-staph broth
35
differential
tells something about the bacteria that grows on it; everybody grows has ingredients that differentiate organisms ex: blood agar
36
both selective and differential
mannitol salts agar
37
macronutrients
required in large amounts | C, N, P, S, K, Mg, Ca, Na
38
micronutrients
required in small amounts | Co, Zn, Mo, Cu, Mn, Ni, W, Se
39
iron (fe)
often considered a trace metal but required in large amounts than other trace metals
40
chelators
chemicals that bind metal ions
41
phototroph
use light as energy source
42
chemotroph
uses chemicals as an energy source
43
chemoorganotroph
uses organic chemicals
44
chemolithotroph
use inorganic chemicals
45
autotroph
uses CO2 as the carbon source
46
heterotroph
uses carbon from organic sources
47
environmental factors influencing bacterial growth
oxygen tolerance temperature ph availability of water in the environment
48
aerobic vs anaerobic
aerobic: can utilize oxygen anaerobic: cannot utilize oxygen
49
obligate or strict facultative aerotolerant
obligate or strict: must have condition or will die facultative: either condition is okay; best is aerobic because you make more ATP fac aerobe = fac anaerobe aerotolerant: does not use 02 for growth but will put up with it; usually anaerobic, but can put up with some oxygen
50
singlet oxygen
one molecule of oxygen; found in smog
51
carotenoids
converts singlet oxygen to nontoxic form
52
superoxide anion
(O2-)
53
peroxide
(O2^2-) | produced by all organisms aerobically
54
hydroxyl radical
(OH) | most reactive of them all
55
oxygen produces toxic intermediates...
singlet oxygen superoxide anion peroxide hydroxyl radical
56
cardinal temperature range
range of growth temperature | 30-40 degrees C
57
minimum temperature optimum temperature maximum temperature
no growth growth is fastest no growth
58
psychrophilic
low optimal temperature | -5 to 20 degrees C
59
mesophilic
mid range optimal temperature 15-45 degrees c
60
thermophilic
high range temperature | >45 degrees C
61
hyperthermophilic
>80 degrees C
62
psychotolerant
20-30 degrees C but also grow in the cold
63
thermophiles
saturated fatty acids | butter
64
psychrophiles
unsaturated fatty acids | Italian dressing
65
hyperthermophiles
hydrocarbons instead of fatty acids | motor oil
66
acidophiles
low ph
67
alkaliphiles
high ph
68
acid tolerant
does not require low ph for growth but will put up with it
69
halophilic
marine environments
70
halotolerant
does not require salt but will tolerate it
71
xerophiles
very dry environment
72
what are the phases of growth
lag phase exponential phase stationary phase death phase
73
batch/ static culture
growth occurs in a fixed volume of culture medium
74
lag phase
when bacteria are inoculated into fresh medium and are adjusting to the environment length depends on new environment and age of medium
75
exponential/log phase
time of most rapid growth | growth rate or generation time are calculated
76
stationary phase
nutrient is used up or waste products build up | no gain in growth rate
77
death phase
total count may be constant by cells slowly die | if cells lyse, there is a decrease in turbidity
78
continuous culture
allow constant environment may involve a chemostat dependent upon flow rate
79
chemostat
maintains a particular growth phase
80
ways to measure bacterial growth
direct microscopic count cell mass measurements viable counts
81
direct microscopic count
use special slides with grid pattern count living and dead cells cant count clumped cells
82
cell mass measurements
dry cell weight
83
turbidity
measurements of absorbance
84
viable counts
determine the number of colony forming units | sample is diluted and plated onto agar plates and incubated
85
spread plate method
spread cells out over the surface
86
pour plate method
pipette bacterial solution into empty plate and pour molten agar over the top

microbiology exam 2 (1 decks)

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