Practical Flashcards
(113 cards)
1
Q
Selective:
A
designed to suppress the growth of some microorganisms while allowing the growth
of others.
• Example: Mannitol Salts Agar (high salt concentration), MacConkey Agar (crystal violet)
2
Q
Differential:
A
differentiates between organisms through an indicator within the medium that
distinguish different chemical reactions
• Example: Mannitol Salts Agar (mannitol fermentation), Blood agar (ability to break
down RBC’s)
3
Q
Complex/Undefined media
A
Exact composition of ingredients in the broth/agar is unknown TSA/TSB o Beef extract 3 grams o Peptone 5 grams o Distilled water 1,000 mL
4
Q
Synthetic/Defined media
A
Exact quantities of all ingredients are known NH4H2PO4 1 gram o Glucose 5 grams o Sodium chloride 5 grams o MgSO4 x 7H2O 0.2 gram o K2HPO4 1 gram o Distilled water 1,000 liter
5
Q
Methods of Sterilization
A
Autoclaving Dry Heat Sterilization Filtration UV radiation Chemical sterilization
6
Q
Autoclaving
A
o 121° C of steam, 15 psi, 15-20 minutes or longer depending on volume
o For liquids that are not heat sensitive
7
Q
Dry Heat Sterilization
A
o 160-170° C for 2 hours
o For glassware
8
Q
Filtration
A
o For heat sensitive material
9
Q
UV radiation
A
o For surface sterilization
10
Q
Chemical sterilization
A
o For heat sensitive materials
o Ethylene oxide – used often in hospital settings
11
Q
Storage of media
Short-term storage
Long-term storage
A
- Capping with a cotton plug, plastic, or foam cup
* Capping with metal or screw caps
12
Q
Culture Maintenance: Short periods (1-2 months) where cultures are used frequently Long periods of storage for cultures not used frequently
A
- Refrigeration
* Desiccation drying or Lyophilisation freeze drying
13
Q
A colony
A
has cells that are genetically identical because they arise from a single cell.
14
Q
mixed culture
A
a culture that contains more than one type of organism
15
Q
pure culture
A
a culture consisting of one type of organism
16
Q
Colony forming unit (CFU
A
measure of viable bacterial cells within a sample per milliliter
17
Q
Limit of Resolution (or resolving power)
A
actual measurement of how far apart two points must be for the microscope to view them as being separate
Best limit of resolution 2um
18
Q
numerical aperture
A
a measure of a lens’s ability to capture light coming from the
specimen and use it to make an image.
19
Q
Parfocal Lens System
A
An optical system that stays fairly in focus when magnification on the
objective lens is changed
20
Q
Three domains
A
Bacteria, Archaea, Eukarya
21
Q
Prokaryotes vs. Eukaryotes
A
- Prokaryotes: 16S rRNA
* Eukaryotes: 18S rRNA
22
Q
Spirillum volutans
A
spiral shaped
23
Q
Mycobacterium tuberculosis
A
acid fast bacterium
24
Q
Klebsiella pneumoniae
A
capsule stain bacterium
25
Proteus vulgaris
contains flagella (peritrichous arrangement)
26
Cyanobacteria:
| Nostoc
contains heterocysts for N2 fixation
27
Protozoa:
| Euglena
MOtility by lfagella and uses longitudinal fission to divide
28
Subphylum Sarcodina-amoebas
| Amoeba proteus
Movement by pseudopods via cytoplasmic streaming and divides by binary fission
29
Subphylum Sarcodina- ameobas
| Entamoeba histolytica
Causitive agent of amoebic dysentery
30
Phylum Ciliophora-ciliates
| Paramecium
motile by cilia and uses transverse fission to divide
31
Phylum Apicomplexa
sporozoans
32
Phylum Kinetopplastida
| Leishmania donovani
Parasite that causes leishmaniasis
Transmitted through the bite of a sand fly
Open sores on skin that form after weeks or months oftransmission.
33
Photosynthestic protists
| Spirogyra
Green, has filamentous algae and chlorophylls A&B
34
Photo sythetic Protists
| Volvox
Flagellated algae
35
Fungi
nonmotile, absorptive heterotrophs, saprophytes, and are parasitic to plants, animals, and humans sometimes.
36
Yeast- unicellular
| Saccharomyces cerevisiae
ascomycete used in food industry
37
Yeast-unicellular
| Candida albicans
Part of normal flora
38
Yeast-unicellular
| Cryptococcus neoformans
a casual agent of pneumonia and meningitis
39
Molds-filamentous
Hyphae are individual fungal fragments
mycellium are a collection of hyphae
Rhizopus
Zygomycete black bread mold
40
```
Molds-filamentous
Hyphae are individual fungal fragments
mycellium are a collection of hyphae
Aspergillus
Penicillin
```
Deuteromycete
| Deuteromycete
41
Importance of Heat fixing
1. Kills the cells so that stains penetrate better
2. Proteins are denatured so the cells stick better to the slide
3. The slide can be kept longer
42
Simple Staining
A single stain/dye is used to create a contrast between the cell and the background. Simple
staining is used to see the shape, arrangement, and size of the microbe.
43
Basic Dyes
Positively charged so that it attaches to the negatively charged bacterial membrane Example: crystal violet, carbolfuchsin, methylene blue
44
Acidic Dyes
Negatively charged so that it is repelled from the bacterial membrane and stain
background (negative staining)
Example: nigrosin
45
Differential staining
stains whole cells
• Gram stain
• Acid Fast stain
46
Structural stain
stains parts of cell
- Endospore stain
- Flagella stain
- Capsule stain
47
What is a Gram variable result?
After 24 hours, the thick peptidoglycan layer of the cell wall becomes leaky and the crystal violet-iodine complex will not set upon the alcohol rinse.
48
3% KOH test
An alternative to the gram stain. Bacterial colony mixed with 3% KOH. Within 60 seconds it is indicative of a gram negative culture is viscous and stringy. Gram negatice cells lyse and release cellular DNA.
49
Endospore
A dormant and highly resistant form of bacterium that can survive in harsh and stressful conditions that would normally kill it to preserve its genetic material. Keratin is apart of their outer covering that helps with stand tough environment.
50
Sporulation
When harsh conditions arise, the bacteria will cease normal growth and produces the resistant endospore.
51
Vegetative cells
Cells without an endospore
52
Sporangium
The part of the cell surrounding the mature endospore
53
Central spores
Spores located in the middle of the sporangium
54
Terminal spores
Spores at the end of the sporangium
55
Free spores
Spores released into the environment
56
Endospore stain
Differential stain used to detect the presence and location of spores in bacterial cells.
57
Genera that produce spores
Bacillus,
Clostridium,
Sporosarcina,
and Sporolactobacillus
58
Bacillus anthracis
anthrax
59
Clostridium tetani
tetanus
60
Clostridium botulinum
botulism
61
Clostridium perfringens
gas gangrene
62
Clostridium diffcile
pseudomembranous colitis
63
Endospore can be cultivated in lab using
NSM Nutrient Sporulation Media
| contains calcium, maganese, and maganesium to promote sporulation.
64
Negative Stains
Used for bacteria who are to delicate for heat fixing. Negative stains contain chromogens that have negative charge that repel off the negative membrane. India ink nigrosin, congo red, and eosin are negative stains.
65
Klebsiella pneumoniae
The casual agent of pneumonia
66
Acid-Fast Stains
Is a differential stain for bacteria with mycolic acis in their cell walls.
67
Ziehl-Neelsen method
Used to stain acid-fast bacteria
68
Carbolfuchsin
Primary stain in acid-fast and contains phenol. Helps dissolve some of the liped on the waxy cell wall.
69
Acid alcohol
Removes carbolfuchsin on negative acid-fast bacteria.
70
Methylene blue
Counterstain that will stain acid-fast negative cells
71
Mycobaterium leprae
acid-fast leprosy
72
Mycobacterium tuberculosis
acid-fast tuberculosis
73
Nocardia
acid-fast
74
Cryptosporidium oocysts
acid-fast causes diarrhea in humans
75
Isopora oocysts
acid-fast
76
Capsule stain
Starts as a negative stain because the capsule is not stained but the background is. Once the background is stained the cell within the capsule is stained with crystal violet or safrinin
77
Capsule
made up of mucoid polysaccharides or peptides and is heat sensitive
78
Virulence
the degree to which a pathogen can cause a disease
79
Bacillus anthracis
Contains a capsule
80
Steptococcus pneumoniae
Contains a capsule
81
Flagella Stains
Mordants are used to increase thickness of the flagella. Then the flagella are stained with a dye such as basic fuschin.
82
Flagella
Are longthreadlike appendages which provide motility
83
```
Flagella arrangments:
monotrichous
Lophotrichous
Amphitrichous
Peritrichous
```
- Single flagellum (polar)
- Tufts of flagella at the end of the cell
- Single flagellum at each end of the cell
- Flagella emerging from the entire cell surface
84
Proteus vulgaris
May cause UTI's, bacteremia, and pneumonia
85
Brownian movement
Is when a bacterial cell is stationary and exhibits a shaking motion due to the bombardment of water molecules.
86
Aerotolerance
The ability or the inability to survive in the presence of oxygen
87
Obligate aerobes
Microbes will only grow in the presence of oxygen
88
Obligate anaerobes
Microbes will grow in the absence of oxygen
89
Facultative
Microbes grow in the presence or absence of oxygen
90
Microaerophiles
Microbes that grow below the surface of the medium because they require a lower than atmospheric oxygen tension for normal growth
91
Gas pak anaerobic system
packet contains inorganic carbonate, activated carbon, ascorbic acis, and water. inorganic carbonate converts into carbon dioxide
92
Catalase Test
Used to differentiate between similar groups of bacteria such as Staphylococcus and micrococcus which are positive, versus Lactococcus and Enterococcus which are catalase negative.
-Hyrogen peroxide will bubble if positive
93
Flavoprotein
Catalase test
| One carrier molecule of electrons to oxygen used in the ETC
94
When flavoproteins carry electrons down the ETC, two cellular toxins, ___ and ____ are formed
Hydrogen peroxide and superoxide molecule O2-
95
Superoxide dismutase
an enzyme that catalyzes the destruction of the superoxide molecule into hydrogen peroxide and oxygen
96
Catalase
An enzyme by some obligate aerobes and facultative anaerobes that break down the hydrogen peroxide into water and atmospheric oxygen
97
Oxidase Test
Used in clinical procedure. Detects the presence of cytochrome C.
98
Cytochrome C
Carrier molecule that transfers electrons to oxygen in the electron transport chain.
99
Cytochrome C Oxidase
An enzyme found in some obligate aerobes, facultative anaerobes, and microphiles that catalyze the transfer reaction. Cytochrome C becomes oxidized while O2 becomes reduced.
100
Oxidase positive
Neisseria (gonorrhea) and Vibrio (cholera) blue strip color change
101
Oxidase negative
Enterobacteriaceae (enteric bacteria)
102
Nitrogen Reduction Test
It tests the ability of an organism to reduce nitrite to nitric oxide, or molecular nitrogen.
103
Positive Nitrate Reduction Test
medium turns red after reagent A and reagent B has been added OR no color change even after zinc has been added.
104
Negative Nitrate Reduction Test
Medium turns red after the addition of zinc
105
Nitrate reductase
Used in nitrate broth to reduce nitrate to nitrite
106
Nitrate Reduction Test Reagent A
Sulanilic acid
107
Nitrogen Reduction Test Reagent B
Alpha naphthylamine
108
Mannitol Salt Agar
Selective (7.5% NaCl) and differential (mannitol and phenol red) medium.Bacteria that can survive the high salt content flourish on this media. MSA isolates pathgenic bacteria from non-pathogenic
109
Mannitol Salt Agar pH indicator
```
Phenol Red
pH:
6.8 or below turns yellow (fermentation of acid)
7.4-8.4 stays red
8.4 and above media turns pink
```
110
MacConkey Agar
Selective and differential medium. Bile salts and crystal violet make it selective by inhibiting growth of Gram-positive bacteria. Neutral red and lactose makes it differential. Acid is formed when certain species of enteric bacteria ferment lactose
111
MacConkey Agar pH indicator
Neutral red.
pH:
6.8 and below lactose fermentation colonies are red
6.8 and above lactose not fermented Growth of the colonies colorless or transparent
112
Salmonella typhi & Shigella dysenteriae
Do not ferment lactose
113
Escherichia coli, Enterobacter, and Klebsiella
Lactose fermenter
