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Microbio > Lab exam 1 > Flashcards

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
Q

3 major types of hemolysis

A

B: complete destruction (clearing)
A: partial destruction (green)
y: no hemolysis

26
Q

hemolysis

A

destruction of RBC

27
Q

germicides and 3 categoris

A
  • prevent spread of pathogens
  • decontamination, disinfection, sterilization
28
Q

decontamination

A
  • lowest level of control
  • reduction of pathogenic microorganisms to a level which items are safe to handle without protective attire
  • soaps, detergents
29
Q

disinfection

A
  • 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
Q

sterilization

A
  • complete elimination of viable organisms including spores
  • autoclaves 121-127 C
31
Q

steam sterilization indicators

A

purple: good
clear: acidic condition from fermentation

32
Q

what are bacterial stains useful for?

A
  • cell size
  • cell morphology
  • cellular arrangement
33
Q

pleomorphism

A

a single species that exhibits a variety of cell shapes within a given sample

34
Q

what do stain solutions consist of?

A
  • solvent
  • chromogen (chromophore-color, auxochrome- charge)
35
Q

simple stains

A
  • 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
Q

negative stain

A
  • to determine morphology and cellular arrangement in bacteria that are too delicate to withstand heat-fixing
  • neg cell and background is neg stained
37
Q

differential stain: gram stain

A

differentiate between Gram + and Gram -

38
Q

why do Gram + cells resist decolorization?

A

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
Q

Differential Stains: Acid Fast Stain

A
  • 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
Q

endospore

A
  • 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
Q

spore location

A
  • central (middle of cel)
  • terminal (end of cell)
  • subterminal (between end and middle)
42
Q

spore shape

A

spherical
elliptical (oval)

43
Q

Differential stain: endospore stain

A
  • 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
Q

Categories of flagellation in Flagella Stain

A
  • monotrichous- single flagellum
  • peritrichous- flagella all around
  • amphitrichous- flagella at both ends
  • lophotrichous- flagella on one end
45
Q

What temperature do you need to cool the agar for a Pour Plate to not kill all of the cells

A

50 C

46
Q

How would you identify the only lens in which you would use immersion oil?

A

Has a black and white ring around it

47
Q

How would you calculate the total magnification of a microscope?

A

Ocular lens x objective lense

48
Q

What is an ocular micrometer?

A

A ruler

49
Q

mordant

A

chemical that helps to fix another chemical in place by complexing with it

50
Q

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?

A

After de-colorization with alcohol

51
Q

source of getting a poor/ inconsistent Gram stain

A
  1. Over de-colorizing
  2. Incorrect preparation of the emulsion
  3. Having old bacteria
52
Q

Under which circumstances would you choose a negative stain protocol over a Gram stain?

A

If the bacteria would lose their delicate shape or shrink when heat fixing

Microbio (5 decks)

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