Microbiology > Lab final > Flashcards

Lab final Flashcards

(107 cards)

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1
Q

What is numerical aperture?

A

Ability to gather light and make a sharp image

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2
Q

What is parafocal?

A

Ability to stay focused on subject when magnification is changed

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3
Q

What is focal distance?

A

Something to do with optical power/distance of lenses to its focus

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4
Q

What is resolving power?

A

Ability to separate two close objects under magnification

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5
Q

How do you calculate total magnification?

A

Multiply the two numbers

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6
Q

Why is immersion oil used with a 100x objective lense?

A

Reduces light refraction for a clearer image

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7
Q

What is a pure culture?

A

Culture of bacteria with a single microbial species

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8
Q

Why is a pure culture important?

A

Allows for accurate examination of a single critter type without interference

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9
Q

What is a mixed culture?

A

Sample with two or more species

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10
Q

How is a pure culture achieved?

A

Isolating individual cells from a mixed population and allowing them to grow into a colony on a sterile growth medium

Done via streak plate and pour plate method

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11
Q

What is the streak plate method?

A

Streaking throughout the plate with a loop and then you can see unique colonies throughout the plate

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12
Q

What is the pour plate method?

A

Where you dilute a sample and pour into plates to do a count

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13
Q

What is the countable range for pour plate method?

A

30-300 colonies

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14
Q

What is simple staining?

A

The use of a single dye on a subject to visualize it better

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15
Q

What is a chromophore?

A

The part of a molecule responsible for its color, determined by its ability to absorb and reflect specific wavelengths of light

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16
Q

What is a negative stain?

A

Where the background is stained but not the subject

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17
Q

What is a negative stain used for?

A

To observe a specimen without altering it in any way with staining

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18
Q

What is a gram stain used for?

A

To see if bacteria is gram negative or positive / assesses cell wall

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19
Q

What colour do gram-positive bacteria stain?

A

Purple or blue

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20
Q

Describe the cell wall of gram-positive bacteria

A

Thick peptidoglycan layer

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21
Q

What colour do gram-negative bacteria stain?

A

Pink or red

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22
Q

Describe the cell-wall of gram-negative bacteria

A

Thin peptidoglycan layer with bilipid layer

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23
Q

Which is harder to treat, gram negative or gram positive?

A

Gram negative

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24
Q

What is a differential stain?

A

Technique that uses multiple dyes to distinguish between different types of microorganisms based on differences in their cell structures.

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25
What is an antiseptic?
Antimicrobial substance applied to living tissue
26
What is a disinfectant?
Antimicrobial substance applied to surfaces
27
What is a sterilant?
Destroys microorganisms
28
What is a sanitizer?
Reduces the number of microorganisms on inanimate surfaces or human skin to a safe level
29
What is bacteriostatic?
Substance that stops or inhibits the growth of bacteria without killing them
30
What is bactericidal?
Kills bacteria
31
What does staphylococcus look like?
Gram positive cocci in clusters
32
What does streptococcus look like?
Gram positive cocci in chains
33
What does e. coli look like?
Gram negative bacilli
34
What is the temp range of psychrophiles?
Can grow below 0c - ideal temp 15c
35
What is the temp range of mesophiles?
Room tempish
36
What is the temp range of thermophiles?
50-80c
37
What is the temp range of hyperthermophiles?
80-110c
38
What pH of medium do most bacteria like?
Neutral
39
What pH of medium do most fungus like?
Acidic
40
What is Rh factor sometimes called?
D antigen
41
What are two bacteria that are spore forming?
Bacillus and clostridium
42
What is the method used to stain spores?
Schaeffer-Fulton
43
What are the 6 nutrient factors
Food, Acidity, Temperature, Time, Oxygen, and Moisture
44
What is complex media?
Media that contains a variety of ingredients with an unknown or imprecise chemical composition.
45
What is defined media
Medium where all chemical components and their concentrations are precisely known
46
What is selective media?
Medium that contains inhibitory agents to suppress the growth of unwanted microorganisms
47
What is differential media?
Distinguishes between different types of bacteria based on their unique biochemical properties, often by causing a visible color change
48
What are aerotolerant bacteria?
Can tolerate O2 but dont use it
49
What microaerophilic bacteria?
Requires lower level of O2 than in atmosphere
50
How severe are gamma hemolytic step?
Non-severe/non-issue
51
What is acid-fast bacteria?
Microorganism that retains a stain even after being washed with acid, a property due to their waxy cell walls high in mycolic acid.
52
What are two acid fast bacteria?
Mycobacterium and Nocardia
53
What is the stain used for the acid-fast techniques?
Kinyoun method (?) Fushinin, acid alcohol and then methylene blue
54
What colour is acid-fast positive bacteria?
Pink
55
What colour is acid-fast negative bacteria?
Purple or blue
56
What are the steps for gram-staining?
Primary stain, mordant, decolourizer, secondary stain
57
What is the primary stain for gram staining?
Crystal violet
58
What is the mordant for gram staining?
Iodine
59
What does a mordant do?
It is a fixative
60
What is the decolourizer for gram staining?
Alcohol
61
What is the secondary stain for gram staining?
Safranin
62
What does the primary stain do in grams taining?
Stains all cells
63
What does the secondary stain do in gram staining?
Stains gran-negative bacteria
64
What are the steps for endospore/Schaeffer-Fulton staining?
Primary, decolourize, steaming, secondary
65
What does malachite green do?
Stain spores when steamed
66
What does safranin do in endospore staining?
Makes vegetative cells pink
67
True or false: all gram-negative bacteria are bad
False: some are normal flora
68
What is a lactose fermenter?
Can produce acid from the metabolism of lactose
69
What is a non-lactose fermenter?
Cannot produce acid from the metabolism of lactose
70
Note: if there's a slide it's enterococcus
yeah
71
True or false: are beta hemolytic step are bad
True
72
What does streptococcus and enterococcus look like?
Gram positive cocci in chains
73
What does staphylococcus look like?
Gram positive cocci in clusters
74
What are the 3 ways to count colonies?
Standard plate count (most common) Presumptive test (e. coli) Microscopic count (sample is diluted)
75
What type of charge do the chromophores of basic dyes have?
Positive, they are cations
76
What are dyes with a negative charge called?
Acidic dyes
77
What does pleiomorphic mean?
Irregular
78
Negative stains use what kind of dye?
Acidic/negatively charged dyes
79
True or false: negative stains are not usually heat fixed
True
80
What happens if you leave a gram-stain out for too long?
The crystal violet will not stick and all cells will appear gram-negative
81
What happens if the gram-stain is too thick?
All cell may appear gram-positive
82
What happens if too much decolorizer is applied to gram-stain?
Positive cells will appear negative
83
What are endospores?
Dormant and extremely resilient version of bacteria (think like little eggs)
84
What conditions are needed to destroy endospores?
Heat and steam for 15-20min
85
What is mycolic acid?
A waxy lipid found in the cell wall of acid-fast bacteria
86
What is the difference between the kinyoun and Ziehl-Neelsen acid-fast methods?
Kinyoun: uses extra dye to penetrate Ziehl-Neelsen uses heat/steam to penetrate
87
How is a microscopic count done?
A diluted sample is counter under a microscope. Oftentimes has a grid
88
How is most probably number count done?
Sample is placed into tubes with lactose, if gas and acid is produced there is the potential for bacteria. Related to coliforms
89
How is standard plate count done?
Diluted substance is repeated until countable and then math is done to calculate the original concentration quantity
90
What does obligate mean?
Strict/absolute requirement
91
What does facultative mean?
Flexible/adaptable requirement
92
What are potential pathogens?
Pathogens that have the potential to cause harm if natural flora is disrupted or present in a different area that normal
93
What illness does Shigella cause?
Dysentery
94
What can staph. aureus cause?
Wide variety of issues: skin, wound bone infections, TSS and food poisoning.
95
What does coagulase positive/negative mean?
If a bacteria forms clots
96
What is beta hemolysis?
Complete hemolysis where bacteria completely lysis blood cells on agar (BETA = BAD!)
97
What are the 2 most common UTI causing bacteria in young women?
Ecoli and S. saprophyticus
98
What is partial hemolysis called?
Alpha-hemolysis (Not so good, could be worse)
99
What is no hemolysis called?
Gamma-hemolysis (Gamma = great)
100
What is group A strep?
Common bacteria that can cause mild infections but can also cause severe and life threatening infections
101
What is group B strep?
Common bacteria, typically insignificant to adults but serious for newborns. Commonly (harmlessly) colonized in GI tract of adults (B for butt: they do a rectal swab for GBS in pregnant women)
102
What is group C strep?
Causes URI
103
What is group D strep?
Split into enterococci and nonenterococci (don't fully understand)
104
What is Lancefield grouping?
Classifying based on the carb antigens in their walls Agglutination test
105
What does a positive/agglutinated Lancefield test mean?
That carbohydrate antigens are present in the bacterial wall
106
True or false: a light microscope can be used to observe objects smaller than a mm
False
107
Microbiology
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