micro lab exam
What should all work surfaces in the biosafety cabinet be cleaned with at the end of each working day?
5% Biocleanse
What is the optimum time and temperature for HTST pasteurization?
72 °C for 15 seconds
How can you confirm that we have successfully extracted the DNA from the yeast?
Analyze it using gel electrophoresis and the NanoDrop
As you have seen, bacteria can acquire new DNA via conjugation, transformation and transduction. Which bacterial DNA molecule is affected by each of these processes?
Conjugation adds plasmid DNA, transduction and transformation change chromosomal DNA
In the disk-diffusion method, why is the zone of inhibition circular?
Diffusion occurs equally from the outer edges of the circular disk.
What is the structure of plasmid DNA?
Double-stranded circular
What color do endospores and bacteria stain in an endospore stain?
Endospores green, bacteria pink
How does penicillin kill bacteria?
Penicillin targets a cross-linking reaction in cell wall manufacture. By blocking the enzyme responsible, penicillin stops the bacteria from producing new peptidoglycan.
The RAD52 gene can be isolated from the yeast cells. What should we do first so we can isolate the gene we need?
Perform DNA extraction
What is the next step after performing gel electrophoresis to obtain the pure eGFP fragment that has been cut from its plasmid?
Perform an electrophoretic gel extraction
What process is used to "amplify" RAD52 DNA, making large numbers of copies from a small sample?
Polymerase chain reaction
In Class I mode, should the night panel be removed or attached?
Removed. You are protected by air drawn into the cabinet
What is the main source of the free external DNA?
The lysis of cells
According to the Spaulding Classification, why is it important to know how much of a pathogenic risk an item poses to an end-user?
The risk determines how you must decontaminate an item so that the next user doesn't get infected.
What is transformation?
The uptake of extracellular DNA
It is common that only some of the yeast cells will successfully take up the plasmid. How do we determine which yeast colonies contain the pTRE-RAD52-eGFP plasmid?
Through antibiotic selection
Inactive samples can only be removed from the lab after undergoing sterility testing, which must be countersigned. Why is it important that a sterility test is carried out?
To ensure the culture is completely sterile before being removed from the lab
What is the function of a regenerator in a pasteurization system?
To exchange heat
Why do we use an ice bucket during restriction digests and ligations?
To keep enzymes from denaturing
How can the RAD52-eGFP gene construct help us to study the DNA repair mechanism?
We can observe the eGFP
You measured the pH of 3 months old peach juices. The hypothesis that you made was 'After 3 months, fresh peach juice will have the lowest pH.'. Was your hypothesis true?
Yes, fresh peach juice has the lowest pH after 3 months
What is a typical pasteurized food? -Eggs - All answers are correct -Cheese -Wine
all answers are correct
In the disk-diffusion method, bacteria __________
are spread evenly over the agar to make a "lawn" of bacteria
Which one of the following methods of control involves the hottest temperature?
autoclaving
Which of the following lists microbes or microbial structures in order from the hardest to destroy by heat to the easiest to destroy?
bacterial endospores, fungal spores, vegetative bacteria, fungi
What is a typical canned food?
beans
The purpose of DNA ligase in cloning is to __________.
catalyze linkage between two ends of DNA
When preparing to use a BSL-4 positive pressure suit, what is the first thing you should do once you take the suit of the rack.
check that the suit is airtight
A cell that can take up foreign DNA is referred to as __________.
competent
If a bacterial species is aerobic, it uses oxygen as its final electron acceptor and must have which enzyme?
cytochrome oxidase
Reduction of the oxidase reagent p-aminodimethylaniline is due to which oxidase enzyme?
cytochrome oxidase
The cytochromes for the electron transport chain found in bacteria are located in this membrane.
cytoplasmic membrane
The indole production test determines the ability of microorganisms to __________.
degrade tryptophan
The ___________ of the zone of inhibition is measured to determine the effectiveness of an antimicrobial agent.
diameter
Differential media are used to __________.
distinguish among morphologically and biochemically related groups of organisms
Antibiotics are synthetic chemicals.
false
Louis Pasteur invented pasteurization to make milk safer.
false
Only prokaryotic cells have the enzyme catalase.
false
Overusing antibiotics can make humans resistant.
false
Sensitivity to an antimicrobial agent generally corresponds to small zones of inhibition.
false
Temperatures that are lower than a microbe's optimum growth temperature tend to be microbiocidal due to denaturing enzymes.
false
The biohazard bag should be located outside the biosafety cabinet.
false
The oxidase test determines if a bacterial species has a means of dealing with hydrogen peroxide.
false
The person who was responsible for the 2001 Anthrax Attacks was caught and put in jail.
false
Tyndallization refers to sterilization by autoclaving.
false
Urease test is useful for differentiating lactose-fermenting species of gram-negative bacteria.
false
Tetra Pak combines the properties of all the following packaging materials EXCEPT?
glass
A broad-spectrum antibiotic would likely affect ________________
gram-positive and gram-negative bacteria.
Catalase breaks down which compound into water and oxygen gas?
hydrogen peroxide
Based on what you know about the Kuppelfangs' illness (fever, fatigue, vomiting and diarrhea), what is the most likely cause?
infectious disease
Electroporation is a technique used for __________.
inserting DNA into cells
Temperature can kill microorganisms because __________.
it denature proteins and therefore will affect cellular enzymes
Which type of medium supports the growth of the widest range of bacteria?
nutritive
Which type or lateral gene transfer requires a pilus?
plasmid
A commonly used word to describe MRSA is...
superbug
How do they determine if super steam sterilization was successful on canned goods?
temperature probe
The MIC (minimum inhibitory concentration) is...
the lowest concentration of a substance that prevents bacterial growth.
A bactericidal chemical kills bacteria.
true
As the temperature of pasteurization increases, the time of treatment decreases.
true
In general, moist heat kills microorganisms in less time than dry heat.
true
One component of shelf life is the growth of pathogens.
true
Some gram-negative enteric bacteria may be catalase-positive.
true
Some of the differences between a fume hood and a biological safety cabinet (BSC) are that a BSC protects both the user and the material inside the cabinet and that the exhaust is HEPA filtered?
true
The oxidase reagent p-aminodimethylaniline oxalate is a light-pink reagent that will turn a blackish color after reduction by cytochrome oxidase.
true
When looking at a blood agar plate with bacterial growth, beta is complete lysis of the red blood cells, alpha is partial lysis, and gamma is no lysis.
true
When two antimicrobial agents cause a greater effect when present together than either causes alone, synergism has occurred.
true
What type of microbe is a bacteriophage?
virus
Should we put on the side panel in Class I mode? The side panel should be put...
... on, so there is a stronger airflow into the front aperture of the cabinet
The Gram stain provides a lot of clinically useful information but it won't give you all the information you need for identification and treatment. About which of these do you NOT learn anything from the Gram stain?
Ability of the bacteria to process nutrients
Which stains are used to visualize structures in the membrane?
Acid-fast and Gram
Who publishes the Laboratory Biosafety Guidelines? -All answers are correct. -Occupational Safety and Health -Administration (OSHA) -The American Society of Microbiology (ASM) -The Centers for Disease Control and Prevention (CDC)
All answers are correct
Why did we pick a single colony? -All answers are correct -To avoid large genetic variance in the expanded culture -To ensure all cultured yeast cells are identical -To ensure all cells grown are genetic clones of a single original cell
All answers are correct
You measured the pH of all three peach juice samples immediately after processing. At that point, what was the pH of the various juices?
All juice samples have similar pH levels
Why is it important to have individual colonies? -All of these statements are correct -To look at motility -To look at colony morphology -To obtain a pure culture
All of these statements are correct
For anthrax, we use Containment Level 3 (BSL-3). Which facilities we must use if we have an Ebola sample? Correct!
BSL-4
We've got a probe and a kidney dish. The probe was used to explore the patient's teeth so it will have been in contact with both mucous membranes and the outside of teeth. How would you classify the dish and the probe if they were used as normally intended? Critical objects are designed to contact normally sterile tissue. Semicritical items ordinarily make contact only with mucous membranes or the skin. Noncritical items normally only ever contact intact skin and do not touch mucous membranes
Both would be semi-critical
How is an antibiotic susceptibility test performed when a physician or dentist sends a clinical sample to the lab?
By performing the Kirby-Bauer test
Which of these factors apply to a biosafety cabinet in Class III mode?
Class III mode provides a physical barrier between the user and the microbes
Canning is designed to destroy all microbes including the most heat resistant microbes. What is the example of heat resistant microbes?
Clostridium botulinum
___________ kills pathogens and some spoilage organisms but does not sterilize substances.
Pasteurization
When fumigating the lab, which of the following should NOT be carried out?
Fridge and freezer doors should be cleaned and opened
When should gloves and oversleeves be worn in a BSL-3 lab?
Gloves should be worn at all times, but oversleeves only when working with the cabinet
What type of pathogen is Bacillus anthracis?
Gram-positive, rod-shaped bacterium
The acronym HEPA (as in HEPA Filter) stands for:
High-Efficiency Particulate Air
What is transduction?
Host DNA is packaged into a viral capsid by chance and is transferred to a new host cell.
When working with infectious biological material, the best place to perform the work would be: Correct!
In a Biological Safety Cabinet
What will happen to the peach juice if we apply heat at 135 °C (275 °F) to it?
It becomes sterilized
Why do you think Bacillus anthracis is classified as Hazard Group 3?
It may spread to the community, but treatment is usually available
Why is it important that a negative air pressure is maintained inside the Biosafety level 3 (BSL-3) lab?
It minimizes the chance of a microorganism leaving the lab
Once you have completed your training, which of these factors is NOT important with respect to your buddy Marie in BSL-3?
Marie should remain in the lab with you at all times
You counted the viable bacteria in all three peach juice samples. Is the hypothesis 'All juice treatments will have a similar viable microbial cell counts.', correct?
No, canned peach juice has the lowest level of viable microbes
What color would colonies of a non-fermenter, such as Proteus mirabilis, be on MacConkey agar?
Non-lactose fermenters do not produce acid, and their colonies appear tan and frequently colorless.
Which of the following is not a BSL-3 organism?
Saccharomyces cerevisiae
What is the difference between selective and differential media?
Selective media inhibit the growth of certain bacteria, differential media distinguish different bacteria from each other
Why does spoiled food become sour?
Spoilage microbes produce acid
We've got a probe and a kidney dish. The probe was used to explore the patient's teeth so it will have been in contact with both mucous membranes and the outside of teeth. Which sterilization method do you think would be best for these items?
Steam and high pressure will kill everything; let's use the autoclave.
What is the difference is between decontamination and sterilization?
Sterilization is a type of decontamination, but not all decontamination techniques result in true sterilization
What do we highlight when we talk about antimicrobial resistance?
The ability of a microbial strain to withstand the effects of a previously effective antimicrobial agent
When we say an antimicrobial agent exhibits 'selective toxicity', what do we mean?
The agent is only toxic to microbial cells because is targets a cell component only found in microbes and not present in the host organism.