Lab Exam 2 Flashcards
1
Q
What are Koch postulates?
A
- Diseased organisms are diseased while healthy individuals are healthy
- Disease must be isolated and grown in the lab
- Inoculate a healthy host with the cultured disease to see if it causes the same disease
- reisolate disease and see if it is the same as original disease
2
Q
What type of bacteria did we try to isolate from the yogurt?
A
Streptococcus thermophilus
3
Q
Why did we only use 1 single colony of bacteria to inoculate in to the tube of milk?
A
To see if the “disease” yogurt will cause the same disease in the healthy (milk)
4
Q
Why was it important to use only one type of colony to work with when viewing under the microscope?
A
To ensure we are looking at the same pathogen that is causing the disease
5
Q
What is Koch postulates used for?
A
To determine the causative pathogen in animals, humans, and plants
6
Q
Characteristics of healthy state milk
A
- no smell, liquid, white w/ ph of 6.2
7
Q
Characteristic of diseased yogurt
A
- sour like smell, thick, white and ph of 4.0
8
Q
What did the inoculation of milk do to it?
A
Caused it to become diseased - turned into yogurt
9
Q
What characteristics (physical/chemical) cause a diseased and healthy individual different?
A
Color, smell, texture, ph
10
Q
What could be done using modern technology to find out for sure that the same bacteria inoculated is the same bacteria causing the disease?
A
Sequence them!!
Take the diseased original and the inoculated disease and sequence the genome to see if the are the same pathogen
11
Q
How did we know the reisolated bacterium was the same as the original bacterium causing disease?
A
They has the same color, consistency, ph and smell
(Same characteristics)
12
Q
What are the 3 forms of physical media
A
Solid , semi solid and broth
13
Q
What are the 2 types of chemical forms of media
A
Complex media & chemically defined media
14
Q
Complex media
A
Media (nutrient broth & niftiest agar) that is enriched with yeast extract or beef extract
15
Q
What is complex media used for?
A
Routine lab works to provide food for heterotrophic bacteria
16
Q
Chemically defined media
A
More specific!!
Media with known amount of chemicals used
17
Q
What is chemically defined media used for?
A
Grow organisms that require special requirements or exclude certain organisms
18
Q
What are the 3 special purpose medias types.
A
Selective, differential and enriched media
19
Q
Selective media
A
Suppress the growth of unwanted bacteria by encouraging growth of wanted bacteria
20
Q
Differential media
A
Allows to distinguish between 2 different bacterial species growing
More physical!
21
Q
Enriched media
A
Contain nutrients to Favor the growth of a certain bacteria
22
Q
Example of selective media
A
MacConkey agar
23
Q
Example of enriched media
A
Blood agar and chocolate agar
24
Q
Differential media example
A
Blood agar
25
What are the 5 ways of sterilization?
Autoclaving, incineration, filteration, ultraviolet irradiation, chemical sterilization
26
Autoclaving
Expose steam at high temperatures and pressure in chamber to sterilize glassware and media
27
Incineration
Dry heat to destroy contaminated material
- such as sterilizing loop/needle
28
Uv (ultraviolet) irradiation
Uv lights that damage dna
29
Chemical sterilization
Uses ethylene gas to sterilize heat sensitive items (plastic) by denaturing proteins
30
Filtration
Excludes microbes by being passed through a filter with pores
31
When is filtration used for?
To sterilize media that is inactivated by heat like antibiotics
32
Do disinfectants completely sterilize
TRUE or FALSE
No!!
It doesn’t kill them but rather reduces their growth
33
Disinfectants include
Microban, anti bacterial soap, bleach
34
What was the boiling water bath used to melt the agar in the media lab not sufficient enough to sterilize the media?
The temperature was 100 degrees Celsius which isn’t high enough to kill microbial life
35
Difference between sterilization and disinfection
Sterilization- removal of microbial life
Disinfection- reducing the amount of microbes present
36
What bacteria in the soil lab produces antibiotics
Streptomyces
37
What chemical produces the soil smell
Geosmin
38
What antibiotic was produced from streptomyces griseus
Streptomycin
39
What group does streptomyces belong to
Actinomycetes
40
What type of media was used in the soil lab? And why was it used?
Selective agar - AIA
— favors growth of actinomycetes and suppresses growth of molds
41
What are the characteristics of streptomyces colonies
Small, opaque, white, dry, powdery
42
Is streptomycin an narrow or broad spectrum of antibiotic?
Broad spectrum since it inhibits the growth of more then one broth culture
43
Total dilution =
Serial dilution x plating dilution
44
Plate dilution in soil lab
50ml on each plate -
1/100
45
What are the 4 other antibiotics produced by the genus streptomyces
Tetracycline, erythromycin, gentamicin, streptomycin
46
What are common food pathogens
E. coli, salmonella, shigella
47
How do you prevent food borne illness?
Properly washing vegetables, cooking meat all the way and using clean utensils
48
Do all food with a high CFU/g make you sick?
No!!
Some can contain good or healthy bacteria
49
Colony morphology
General appearance of bacterial colony ( shape, color, texture, size)
50
Why is colony morphology used?
To determine the identity of bacteria species and distinguish between differ t bacteria growing on the same plate
51
Why can bacteria colonies very in appearance?
Due to growing at different temperatures or growing on a different media type
52
What are the 8 ways to describe colony morphology
Configuration
Margin
Elevation
Size
Color
Texture
Optimal properties
53
Configuration describes
The shape
54
Margin describes
The edge or boarders
55
Elevation describes
The height of the colony
56
Examples of describing configuration
Round, irregular, rhizoid, filamentous
57
Examples of explaining the margin of colonies
Smooth, wavy, rhizoid, filamentous, curled, lobate
58
Examples of explains the elevation of bacterial colonies
Flat, raised, convex, droplike, fried egg
59
Examples of color to describe bacterial colonies
White, clear
60
Examples of sizes to describe colony morphology
Small, medium, large, x large
61
Examples of optimal properties to describe colony morphology
Translucent, opaque, shinny, dull, transparent
62
Examples that describe the surface texture
Smooth, rough, wrinkled, dry, moist and shiny
63
Chemical disinfectants are used to prevent/ reduce the growth of microbes on surfaces
TRUE or FALSE
True!!
64
Sterilization
Destruction of all microbial life enclosing endospores
65
Disinfection
Destruction of pathogens on inanimate objects
66
Antisepsis
Destruction of pathogens on living tissue
67
Sanitization
Lowering microbial counts on surface to safe level ( eating utensils)
68
Bactericidal
Substance that kills bacteria
69
Sporicidal
Substance that kills spores
70
What chemical agent is microban made out of?
Quat and alcohol
71
What are the 4 chemical methods (types) used to control microbial growth?
Halogens, alcohol, quats, peroxide
72
WhT are some of the most resistant microbes
Prions, endospores or bacteria & mycobacteria
73
Why are mycobacteria resistant to disinfection?
They have a waxy cell wall that resists disinfectants
74
What are more resistant to a disinfectant gram - or gram +?
Gram negative are more resistant due to having an outer membrane
75
What are some of the least resistant microbes to disinfection?
Viruses and gram +
76
Clorox wipes and antibacterial soap are what chemical agent
Quats
77
Quats (quartering ammonium compounds) mechanism
Protein denature
Disruption of plasma membrane
78
Bleach is an example of what chemical agent
Halogen
79
Halogens mechanism of action
Alter cellular components
➡️ strong oxidizing agent
80
Alcohol based hand sanitizer is an example of what chemical agent
Alcohol
81
Alcohol’s mechanism of action
Denatures proteins
Disrupts plasma membrane
82
Regular hand soap is an example of what chemical agent
Surfactant
83
Surfactant mechanism of action
Washes away microbes ➡️ inserting into membranes
84
Providence iodine is an example of what chemical agent
Halogen
85
Hydrogen peroxide is an example of what chemical agent
Hydrogen peroxide
86
Hydrogen peroxide mechanism of action
Alters cellular components by removing e- ( oxidizing agent)
87
What are some ways to collect bacteria from a person?
Body surfaces - skin
Blood
Urine, stool or saliva
88
How is bacteria collected from body surfaces?
Sterile swabs
89
How is urine or stool collected?
Put in a sterile container
90
How is blood collected for analysis?
Collected via sterile tube
- one aerobically and one anaerobically
- one w/ positive growth is streak plated
91
What are three common types of agar media used to grow bacteria in a lab?
Blood agar, chocolate agar, macConkey agar
92
Blood agar
- enriched agar : containing animal blood
93
How is blood agar both an enriched and a differential media?
It has the ability to distinguish pathogens by their ability to break down red blood cells and it’s made of animal blood
94
Chocolate agar
Enriched media - used to culture certain medias such as heamophilus influenzae & neisseria gonorrhoeae
95
How is chocolate agar an enriched he’d media
Lysed with blood cells that bacteria need in order to grow
96
How is macConkey agar a selective and differential media?
Selective - inhibits growth of gram + so gram - can grow
Differential - distinguishes pathogens on their ability to ferment lactose
97
What is added to macConkey agar to inhibit the growth of gram + bacteria?
Bile salts & crystal violet dye
98
What is an example of lactose fermenting bacteria
E. coli
99
What is blood agar used to culture
Pathogenic organisms to see if they can break down red blood cells
100
Hymolysis
The ability for a bacteria to break down red blood cells
101
Alpha hemolysis
Partial breakdown of red blood cells - looks yellow
102
Beta hemolysis
Complete breakdown of red blood cells - looks green
103
Gamma hemolysis
No breakdown of red blood cells - looks clear
➡️ example : staphylococcus epidermis
104
5 steps in isolation and identification of bacteria from clinical samples
1. Culture bacteria
2. Obtain single colony
3. Gram staining
4. Metabolic test to complete plate bacterial Id
5. Antibiotic sensitivity test
105
Lactose fermenting bacteria produces acid that turns colonies pink
TRUE or FALSE
True
White colonies = no fermenting lactose
106
Indigenous microbiota
Microbes that live on or in our bodies
107
Do indigenous microbiota cause disease
No - not under regular circumstances
➡️ opportunistic pathogens can - if in the wrong place t the wrong time ( not where they belong)
108
The Kirby Bauer method
Determines if bacteria is resistant to a particular drug
109
Zones of inhibition
The area in which bacteria can not grow
110
Broad spectrum of antibiotic
The antibiotic is effective against many types of microbes
111
Narrow spectrum regarding antibiotics
Effective against only a couple microbes
112
Antibiosis
Interaction between microbes where at least one is harmed
113
What are 3 tests used to test antibiotics effectiveness?
E test
Vitek susceptibility test
Kirby Bauer method
114
An example of a narrow spectrum antibiotic seen in lab
Penicillin, polymyxin B , Erythromycin
115
Example of broad spectrum antibiotic seen in lab
Ampicillin, gentamicin, streptomycin and tetracycline
116
If a bacteria is resistant to an antibiotic is there a zone of inhibition.
No - antibiotic did not stop growth
117
Which antibiotics we tested are peptidoglycan synthesis inhibitors?
Ampicillin & penicillin
118
What antibiotics did we test are protein synthesis inhibitors?
Streptomyces, tetracycline, chloramphenicol, Erythromycin & gentamicin
119
What antibiotic targets the plasma membrane
Polymyxin B
120
What antibiotic targets gram + bacteria
Erythromycin & penicillin
121
Why are bacteria becoming resistant to many antibiotics
Antibiotics kill heathy and bad bacteria making antibiotics resistant bacteria more able to survive
122
Kirby Bauer method
Test to determine the effectiveness of antibiotics
123
E test
Plastic strip containing different concentrations of one type of antibiotic to find the minimum concentration it inhibits growth
124
Vitek susceptibility test
A card containing wells with different antibiotics
125
Sensitive means
Zone of inhibition is large
126
Resistant means
Zone of inhibition is small
127
What are the 5 things needed for the master mix - put into per tube
Template dna
Buffer
DNTPs (nucleotides)
DNA polymerase
RNA primer
128
Taq DNA polymerase
Heat tolerant enzyme used to copy dna
129
Primers
Short segment of dna that gives dna polymerase starting point
130
Why does taq polymerase require a primer (rna)
It allows the adding of nucleotides to a new strand since taq polymerase can’t do it on its own
131
What does pcr stand for?
Polymerase chain reaction
132
What does a pcr do
Amplifies any dna sequence even from a small sample
133
Amplify means
To make copies
134
What is pcr tests used for
Infectious diseases, forensics and paternity tests
135
What dna did you amplify in pcr lab?
Chromosome 16 from the cheek cell
136
What was the site that was being tested in the pcr test?
Pv92
137
3 steps to pcr test
1. Denature (94c)
2. Annealing (50-65c)
3. Extension (75c)
138
What is the alu sequence
An extra 300 base pairs w/ no known function
139
Why is taq polymerase used in pcr?
It is stable at high temperatures so you don’t need to keep adding it
140
If an individual is Alu +/+ where will the markers be after denaturing stage
One mark at the 941 base pair
141
If an individual is +/- where will the markers be after the gel electrophoresis
One at the 941 base pair and one at the 641 base pair
142
If an individual is Alu -/- where will the markers be after the gel electrophoresis
One at the 641 marker
143
Electrophoresis
Process where dna fragments are separated according to size using electoral charge
144
What about dna molecules allows you to separate them on gel
They have a negative phosphate backbone
145
What is the purpose of adding loading dye in electrophoresis tank
To color the solution of sample
146
What are the two components of the loading dye
Glycerol and bromophenol blue
147
What was the role of glycerol in the loading dye ?
It helps the sample sink to the bottom of the well
148
What is the role of putting bromophenol blue in the loading dye?
It allows us to see the dna on the gel
149
What is the molecular marker purpose
It’s the template used to determine the size of our dna
150
The purpose of the fast blast
To visualize dna
151
What does ELISA stand for
Enzyme linked immunosorbet assay
152
What is an antibody
A protein that acts against a specific antigen by attaching to it so the immune system can attack it
153
What is an antigen
A toxic or foreign substance that causes an immune response in the body
154
Each antibody binds to only a single matching antigen
TRUE or FALSE
True - they bind with specificity
155
How are antibodies produced?
By B cells
156
Where are antigens found
Surface of a pathogen
157
What is tested to see if a patient has had a past infection
Antibody
158
Where are antibodies found in
Plasma membrane
159
What diseases are diagnosed with ELISA
Zika virus, hiv, Lyme disease
160
What non disease is diagnosed with ELISA
Pregnancy
161
If a test is not sensitive enough it might lead to what
A false negative
162
Specificity of a test means
The test react to what it is supposed to
163
If a test is not specific enough it might lead to what
False positive
164
What was the role of horseradish peroxidase [HRP] in the ELISA experiment?
It linked to secondary antibody : produces a blue color when the substrate is added
165
What does the intensity of the blue color indicate in ELISA test
How much antigen is present : darker the blue the more present
166
Primary antibody
Binds to antigen
167
Secondary antibody
Detects binding reaction of primary antibody
168
Why did you assay positive and negative control samples in addition to your experimental samples?
The controls allowed is to know if it was done correctly- if contamination occurred or possible step skipped
