Lab Content Flashcards
Determine the number of bacteria within a 1 kilogram package of ground beef in order to provide a quantitative risk assessment and quality measure before release to public market.
Technical Data: A 1 gram sample of the ground beef was added to 99 ml of sterile saline solution and extensively mixed to resuspend all the bacteria into the solution (final volume 100ml). One millilitre of this mixture was then added to 9 ml of saline in tube A. Then 0.1 ml from tube A was spread evenly onto a growth media plate, and then the plate was incubated for 18 hours at 37 degrees to cultivate E. coli bacteria. After 18 hours, the growth media plate had 18 colonies.
From the experimental data, calculate how many bacteria are within the original 1 kg package of ground beef (considering homogeneity and representative sampling for the experiment).
Write your answer as a complete number (no scientific notation, no commas, no punctuation).
180000000
Objective: Determine the number of bacteria within a 250ml sample of lake water to provide a quantitative risk assessment of fecal coliforms present in a public swimming area.
Technical Data: One ml of the lake water sample was passed through a 0.2 micron paper filter disc via vacuum pressure, capturing any bacterial cells on the filter surface. The filter was then placed on an agar plate to support fecal coliform growth for 24 hours at 30 degrees Celcius. After the 24 hour period, 289 coliforms were apparent.
From the experimental data, calculate how many bacteria are within the original lake water sample, arriving at a fecal coliform/ml of water.
Based on the following water safety guidelines of no more than 200 bacteria/ml, is the lake safe for public swimming?
the lake is not safe for public swimming
Select the heavy atom that can be used to stain virus particles so they can diffract electrons and be visualized.
a) Cesium
b) Radium
c) Sodium
d) Uranium
d) Uranium
Can electron microscopy tell us if a viral particle is infectious or not?
a) No
b) Yes
a) No
Which of the following is NOT a structural component of herpesviruses?
a) envelope
b) viral glycoprotein
c) tegument
d) (+)ssRNA genome
e) nucleocapsid
d) (+)ssRNA genome
What is the approximate diameter of the herpesvirus, KSHV?
a) 100 nm
b) 10 nm
c) 50 nm
d) 300 nm
a) 100 nm
One research objective of the McCormick lab is to discover new antiviral drugs. One drug under investigation, which we will call ‘Drug X’, interferes with coronavirus assembly, whereby the Spike glycoprotein that normally gives coronaviruses their eponymous ‘crowns’, or ‘coronas’, is not incorporated. In these electron micrographs, the viral particles in the top row were collected from infected cells treated with a vehicle control (a ‘vehicle’ is the solvent that a drug is dissolved in). The viral particles in the bottom row were collected from infected cells treated with Drug X and have a smooth appearance that suggests the absence of Spike glycoproteins in the viral envelope (photo credit: Dr. Eric Pringle).
We observed that viral particles collected from Drug X-treated cells fail to infect human cells. What is the primary reason that these viral particles are non-infectious?
a) Failure to create cytoplasmic replication compartments.
b) Failure of the RdRp to copy the (+)ssRNA genome into (-)ssRNA intermediates.
c) Failure to bind to ACE2 receptor on the surface of target host cells.
d) Failure of viral proteases to cut up the viral polyprotein into individual proteins.
e) Failure to inhibit host antiviral responses.
c) Failure to bind to ACE2 receptor on the surface of target host cells.
What is a plaque?
a) A group of virus-infected cells attached to a plate.
b) A colony of bacteria on agar
c) A zone of clearing where the virus has killed a group of host cells.
c) A zone of clearing where the virus has killed a group of host cells.
What containment level is appropriate for, pathogen, Influenza B?
a) Containment Level 1 (CL1)
b) Containment Level 2 (CL2)
c) Containment Level 3 (CL3)
d) Containment Level 4 (CL4)
b) Containment Level 2 (CL2)
Which of the following are components of Dr. Corbett’s Prototype Pathogen Approach to Pandemic Preparedness? (select all correct answers)
a) Study a prototype virus in a virus family, which creates generalizable knowledge that can be applied to a newly emerging member of that virus family.
b) Develop vaccines and/or antivirals against the prototype virus that can be ready-to-go to test against a newly emerging member of that virus family. c) Study a newly emerging virus at the time of its emergence, ignoring past lessons from related viruses.
a) Study a prototype virus in a virus family, which creates generalizable knowledge that can be applied to a newly emerging member of that virus family.
b) Develop vaccines and/or antivirals against the prototype virus that can be ready-to-go to test against a newly emerging member of that virus family.
Which of the following were vaccine targets that Dr. Corbett studied before 2019, to prepare for a future coronavirus pandemic? (select all correct answers)
a) SARS-CoV-2 Spike protein
b) SARS Spike protein
c) HKU1 Spike protein
d) MERS Spike protein
b) SARS Spike protein
c) HKU1 Spike protein
d) MERS Spike protein
Dr. Corbett and her team mutated the MERS-CoV Spike gene to create two amino acid substitutions; valine 1060 to proline, and leucine 1061 to proline. Why was this done?
a) To create a Spike protein that could not be bound by neutralizing antibodies.
b) To destabilize the Spike protein and make it fall apart.
c) To stabilize the Spike protein in a pre-fusion conformation.
d) To create a Spike protein that would be better at binding to cell surfaces.
c) To stabilize the Spike protein in a pre-fusion conformation.
Dr. Corbett and colleagues developed strategies to mutate the Spike gene so the Spike protein would be stabilized in its pre-fusion conformation. Which of the following companies that were developing and testing SARS-CoV-2 vaccine candidates in November 2020 were relying on Dr. Corbett’s prefusion-stabilized Spike approach? (select all correct answers)
a) Pfizer-BioNTech
b) Moderna
c) Astrazeneca
d) Novavax
e) Janssen/Johnson & Johnson
All of them correct
Some proteins are very conserved across different known coronaviruses, which means that the protein sequences are similar. Such proteins could be attractive candidates for future coronavirus vaccine development because a vaccine targeting a conserved protein may generate protective immune responses against multiple viruses in the family, as well as newly emerging coronaviruses. Which of the following coronavirus proteins does Dr. Corbett mention as being highly conserved amongst coronaviruses, and a potentially interesting future target for vaccines?
a) Spike (S)
b) Membrane (M)
c) RdRp
d) Nucleoprotein (N)
e) Envelope (E)
d) Nucleoprotein (N)
YOU are the new laboratory assistant for Dr. Doolittle. He has decided to go on an unannounced vacation and has left vague instructions for you to put together a sandwich ELISA to detect HIV1 in patient samples. His instructions indicate that all the reagents required are in the lab refrigerator. Unfortunately for you the fridge is bursting with tubes of antibodies, some of which are partially labeled, and you have to decide which to use for each ELISA step. Hint: look up HIV1 proteins on wikipedia (https://en.wikipedia.org/wiki/Group-specific_antigen).
Technical Data: You have finished going through Dr. Doolittle’s lab refrigerator. Here is what you have narrowed down the possibilities to (isotype in parentheses). Choose 1 each of the following for Capture, Secondary and Detection:
a)
Dog anti-virus SP2 (IgG3),
Dog anti-virus polymerase (IgG2a),
Pig anti-dog IgM conjugated to horse-radish peroxidase (IgM)
b)
Monkey anti-virus matrix protein (IgM),
Donkey anti-virus P6 (IgG3),
Dog anti-pig IgG3 conjugated to horse-radish peroxidase (IgG1)
c)
Mouse anti-virus nucleocapsid (IgM),
Pig anti-virus nucleocapsid (IgG1),
Goat anti-pig IgG1 conjugated to horse-radish peroxidase (IgA)
d)
Camel anti-virus capsid (IgG1),
Goat anti-virus SP1 (IgG2)b,
Pig anti-goat IgA conjugated to horse-radish peroxidase (IgG2a)
b)
Monkey anti-virus matrix protein (IgM),
Donkey anti-virus P6 (IgG3),
Dog anti-pig IgG3 conjugated to horse-radish peroxidase (IgG1)
