SEA - Phages Lab Final Exam Questions
And Answers 100% Pass
*Explain the difference between sterile and aseptic.* - answer✔sterile - free from bacteria
aseptic - free from contamination caused by harmful bacteria, viruses, or other
microorganisms
*What is a plaque?* - answer✔a clearing in a bacterial lawn resulting from lysis by phages
*A phage genome that is dominant inside a bacterial cell's genome is called a* -
answer✔prophage
Two large biological molecules that compose a phage are: - answer✔proteins and
nucleotides
describe the lytic and lysogenic cycle - answer✔bacteriophage infection results in either a
lytic or a lysogenic cycle:
1. LYTIC CYCLE results in the production of new progeny that cause the cell to lyse
2. LYSOGENIC CYCLE results in incorporation of the viral DNA into the bacterial DNA where
it remains inactive
-- a lysogenic cycle may progress into a lytic cycle
*a bacterium in which a phage has incorporated its genome is called a* - answer✔lysogen
Why do we add the top agar to section 3 of the three-phase streak plate? How does this
relate to the fact that we shouldn't swirl the streak plate? - answer✔Section 3 is where the
most diluted phage exists. Top agar is added to section 3 so it will flow through sections 1
and 2 without crossing the different sections. We shouldn't swirl the streak plate because
this would cause the sections to cross and potential lysis of the entire plate.
Suppose you are lucky and isolate a phage from your soil sample that produces clear 2.0
mm plaques on a M. smeg lawn. You want to do another streak plate but there is no more
M. smeg so you grab a culture tube of E. coli instead. Would you expect to see the same
results after 48 hours? Why? - answer✔No -- only certain phages will grow with certain
host bacteria
When we filter-sterilize our sample with the 0.22 mm filters, why do we still expect to find
phages in the sample? - answer✔the phages are small enough to be filtered through
Compare the plaque morphologies of lytic phages and temperate phages. - answer✔lytic -
clear plaques
temperate - cloudy ("turbid") plaques
bacteria are classified as - answer✔prokaryotes
*What is the purpose of adding nuclease to the DNA extraction?* - answer✔degrade
bacterial DNA
*what is used to wash salts and proteins off column?* - answer✔isopropanol
bacteria are what type of organism? - answer✔prokaryote
compared to other groups, P. acnes phages are unusual because they have: - answer✔less
genetic diversity
In the DNA isolation procedure, what are you trying to isolate? - answer✔phage DNA
the results of enzyme digestion and gel electrophoresis can tell you what about a phage? -
answer✔how similar it is to other phages
separation of fragments on an agarose gel occurs because of differences in: -
answer✔fragment size
True or false: antibiotics are effective against bacteriophages? - answer✔False
a researcher is following the DNA isolation protocol, but in order to save time, decides to
skip the step of adding nuclease to the lysate. Was this a good idea? - answer✔Not a good
idea - the nucleases degrade the bacterial DNA so not adding this would result in bacterial
DNA and phage DNA instead of the intended pure phage DNA sample
what is the host we used in lab? - answer✔Arthrobacter sp.
viruses that infect bacterial hosts and have properties shared by all viruses (unable to
replicate by themselves and are specific to a particular host) - answer✔bacteriophages
2|Page
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Brightstars. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.49. You're not tied to anything after your purchase.
