Exam (elaborations)
Virology Exam 2: Study Questions with Correct Answers
- Course
- Institution
Virology Exam 2: Study Questions with Correct Answers
[Show more]
Content preview
Virology Exam 2: Study Questions with CorrectAnswers
Why must (-) strand viral RNA be coats with protein in the virion? Why
not (+) strand viral genomes? Are there exceptions for the latter? Correct
Answer-(-) RNAs are coated with proteins to allow mRNA synthesis
upon entry (with packaged RdRp), as the RNA is not infectious.
(+) RNAs are not coated because they are translated upon entry.
Exceptions:
(1) retroviral RNA is (+) strand but is coated and has reverse
transcriptase to turn back into DNA.
(2) Coronavirus is (+) strand but is coated because it's very long.
Do all RNA viruses encode their own replication system? Why? Correct
Answer-Yes because host doesn't make RdRp.
For viruses with (-) sense RNA genomes, the (+) strands and mRNA are
the same. True or false? Why? Correct Answer-False: sometimes the
mRNA is shorter than the (+) strand, but the full (+) strand is needed as
a template for the (-) RNA
(1) Influenza: the mRNA is ~20 BPs shorter than the (+) mRNA
(2) VSV: Maybe the same?
, What is the primer for picornavirus replication? The primer for synthesis
of influenza mRNAs? Is all viral RNA synthesis primer-dependent?
Correct Answer-Primer for picorna (polio) = Vpg-pUpU
Primer for influenza: host mRNA that RdRp must use
Not all viral RNA synthesis is primer-dependent! (Examples:
alphavirsues = (+) RNA, VSV = (-) RNA, and reovirus/rotavirus =
dsRNA
Know the flow of information for (+), (-) and ds RNA genomes. Which
genomes are accompanied by an RdRp in the virus particle? How are
proteins encoded in viral RNA genomes? Correct Answer-Know the
Baltimore scheme here!
(-) ssRNA and dsRNA need RdRp in virus particle.
Proteins may be encoded as polyproteins, or by subgeneric mRNAs.
When the genome of a (-)ssRNA virus is purified and introduced into
cells that are permissive for the original virus, does replication occur?
(i.e., is it infectious)? Why? If you did this same experiment with a (+)
sense ssRNA virus, would viral replication ensue? Correct Answer-
(-)RNA is not infectious as no RdRp is present. But (+)RNA is
infectious (will be translated to make proteins)
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 cracker. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $14.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
76710 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now