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Lab exam 1 Flashcards

1
Q

aseptic transfer

A

transfer of living microbes from one place to another without contamination of
1) the culture
2) the sterile medium
3) the surroundings

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2
Q

what is a culture?

A

medium that contains living microbes

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3
Q

pure vs mixed culture

A

pure: 1 species
mixed: multiple species

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4
Q

broths

A

to grow microbes when fresh cultures or large number of cells are required

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5
Q

agar slants

A

for cultivation, maintenance, and storage of stock cultures

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6
Q

plated media

A

for obtaining isolation of species, differential testing, and quantifying bacterial densities

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7
Q

what are the 3 methods of isolation?

A

spread, streak, pour plate

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8
Q

spread plate technique

A
  • diluted microbial sample is put on agar plate and spread uniformly across the surface
  • if properly diluted: CFUs should be deposited far enough apart to grow into individual colonies
  • can be used to quantify cell density of a broth culture
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9
Q

growth characteristics are influenced by:

A
  • nutrient availability
  • temperature
  • incubation time
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10
Q

shape categories

A

round, irregular, punctiform (tiny pinpoint dots)

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11
Q

margin categories

A
  • entire (smooth, no irregularities)
  • endulate (wavy)
  • lobate (lobed)
  • filamentous (unbranched strands)
  • rhizoid (branched like roots)
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12
Q

elevation categories

A

flat, raised, conved, pulvinate, umbonate

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13
Q

texture categories

A

moist, mucoid, butyrous, dry, shiny, dull

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14
Q

filiform

A

dense and opaque with a smooth edge

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15
Q

friable

A

crusty

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16
Q

spreading edge

A

produced by motile organisms

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17
Q

what growth characteristics can organisms cultures on slants display?

A

filiform, friable, spreading edge, pigmented or transparent

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18
Q

pellicle

A

growth floats on top of medium

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19
Q

sediment

A

growth sinks to the bottom

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20
Q

turbid

A

cloudy

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21
Q

flocculent

A

clumped growth

22
Q

saprophytes

A

perform important role of decomposition in ecosystem

Live in dead or decaying matter

23
Q

reservoir

A

where a microbe with the potential to cause infection resides

24
Q

what is the purpose of blood agar and what does it include?

A
  • to differentiate bacteria based on hemolytic characteristics
  • 5% sheep blood in a Tryptic Soy Agar base
25
3 major types of hemolysis
**B**: complete destruction (clearing) **A**: partial destruction (green) **y**: no hemolysis
26
hemolysis
destruction of RBC
27
germicides and 3 categoris
* prevent spread of pathogens * decontamination, disinfection, sterilization
28
decontamination
* lowest level of control * reduction of pathogenic microorganisms to a level which items are safe to handle without protective attire * soaps, detergents
29
disinfection
* low, medium, high * kill most (if not all) of pathogens but not many spores * typically liquid * **chemical**: kill all vegetable cells and some spores * **antiseptics**: to reduce/ eliminate pathogens on or in living tissue
30
sterilization
* complete elimination of viable organisms including spores * autoclaves 121-127 C
31
steam sterilization indicators
**purple**: good **clear**: acidic condition from fermentation
32
what are bacterial stains useful for?
* cell size * cell morphology * cellular arrangement
33
pleomorphism
a single species that exhibits a variety of cell shapes within a given sample
34
what do stain solutions consist of?
* **solvent** * **chromogen** (chromophore-color, auxochrome- charge)
35
simple stains
* stain heat-fixed cells with a colored dye to make them more visible under microscope * auxochrome picks up H+ or loses OH- and becomes POSITIVELY CHARGED
36
negative stain
* to determine morphology and cellular arrangement in bacteria that are too delicate to withstand heat-fixing * neg cell and background is neg stained
37
differential stain: gram stain
differentiate between Gram + and Gram -
38
why do Gram + cells resist decolorization?
**Gram +**: thicker peptidoglycan layer and greater cross-linking of because of teichoic acids (traps crystal violet-iodine complex and resist decolorization **Gram -**: higher lipid content and thinner peptidoglycan layer. Alcohol step extracts the lipid --> cell wall more porous and incapable of retaining primary stain
39
Differential Stains: Acid Fast Stain
* based on presence of mycolic acids in the cell wall of acid-fast positive organisms * **mycolic acid**- waxy lipid that provides a higher affinity for the primary stain and resistant to decoloration * used to identify bacteria in Mycobacterium genus
40
endospore
* dormant form of bacterium that allows it to survive poor env. conditions * resistant to heat and chemicals because of tough outer covering of keratin
41
spore location
* central (middle of cel) * terminal (end of cell) * subterminal (between end and middle)
42
spore shape
spherical elliptical (oval)
43
Differential stain: endospore stain
* to detect presence/ absence of spores in bacterial cells * **spores**: green **vegetative cells and spore mothers**: red * **only a few genera produce spores: * **Bacillus Clostridium
44
Categories of flagellation in Flagella Stain
* **monotrichous**- single flagellum * **peritrichous**- flagella all around * **amphitrichous**- flagella at both ends * **lophotrichous**- flagella on one end
45
What temperature do you need to cool the agar for a Pour Plate to not kill all of the cells
50 C
46
How would you identify the only lens in which you would use immersion oil?
Has a black and white ring around it
47
How would you calculate the total magnification of a microscope?
Ocular lens x objective lense
48
What is an ocular micrometer?
A ruler
49
mordant
chemical that helps to fix another chemical in place by complexing with it
50
After which of the following steps in the Gram stain process could you detect a difference between Gram + and Gram- bacteria if you looked really hard?
After de-colorization with alcohol
51
source of getting a poor/ inconsistent Gram stain
1. Over de-colorizing 2. Incorrect preparation of the emulsion 3. Having old bacteria
52
Under which circumstances would you choose a negative stain protocol over a Gram stain?
If the bacteria would lose their delicate shape or shrink when heat fixing

Microbio (5 decks)

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