Altklausurfragen Flashcards
A cell is:
-Permissive for a virus when the cell can be infected
-permissive for a virus when genome replication is possible
-susceptible for a virus when cell can be infected
-susceptible for a virus when genome replication is possible
True or False
A cell is:
- Permissive for a virus when the cell can be infected -false ?
- permissive for a virus when genome replication is possible -true
- susceptible for a virus when cell can be infected -true
- susceptible for a virus when genome replication is possible -false
What is a viroid?
Small infectious RNA molecules, encode no protein
Describe the viroids properties and give on example.
• small (200-400 nt), circular RNA • self-complementary, rod-like secondary structure • encode no protein • no capsid or envelope • replicate in nucleus or chloroplast Example: coco palm cadang-cadang viroid
Genome replication of DNA viruses: True or false?
- Genome amplification of SV40 involves the action of Topoisomerase and primase.
- Genome amplification of SV40 involves base pairing of self-complementary genome ends.
- Genome amplification of SV40 uses a protein primer.
- Genome amplification of adenovirus involves classical leading and lagging strand DNA synthesis
- genome amplification of adenovirus involves the action of DNA ligase
- amplification of polyoma virus SV40 genomic DNA is similar to eukaryotic DNA replication.
Genome replication of DNA viruses: True or false?
- Genome amplification of SV40 involves the action of Topoisomerase and primase. - true
- Genome amplification of SV40 involves base pairing of self-complementary genome ends. -false
- Genome amplification of SV40 uses a protein primer. -false
- Genome amplification of adenovirus involves classical leading and lagging strand DNA synthesis -false
- genome amplification of adenovirus involves the action of DNA ligase -false
- amplification of polyoma virus SV40 genomic DNA is similar to eukaryotic DNA replication. -true
Influenza Virus: True or false
- base pairing between both ends of each genome segment
- PA catalysts cleavage of cellular pre-mRNA
- PB1 is the cap binding protein
- 7 genome segments
- All viral proteins contain nuclear localisation signal
- viral RNA is infectious on its own
- uses cellular splicing apparatus
- uses cellular PolyA-polymerase for mRNA poly-adenylation
Influenza Virus: True or false
- base pairing between both ends of each genome segment -true
- PA catalysts cleavage of cellular pre-mRNA -true
- PB1 is the cap binding protein -false (PB2 ist the cap binding protein)
- 7 genome segments -false (8)
- All viral proteins contain nuclear localisation signal -false(only NP and PB2)
- viral RNA is infectious on its own -false
- uses cellular splicing apparatus -true
- uses cellular PolyA-polymerase for mRNA poly-adenylation -false (poly adenylation through stuttering of the viral polymerase at 3’ end
List four methods for the quantification of influenza virus particles. Explain why you get different numbers for the same virus preparation with these methods.
-electron microscope (EM/ml)
-pock assay (egg ID50/ml)
-hemagglutination (HA units/ml)
-plaque formation (pfu/ml)
The numbers variate: infectious particles vs subunits vs all particles
There are three different mechanisms to generate capped viral genomic RNAs.:
1. De novo synthesis by cellular enzymes
2. Synthesis by viral enzymes
3. Acquisition of preformed 5’cap structures from cellular pre-mRNAs or mRNAs
Place the following virus families in the right category:
Adenoviridae, Bunyaviridae, Hepadnaviridae, Herpesviridae, Orthomyxoviridae, Papillomaviridae, Poxviridae, Reoviridae, Rhabdoviridae, Togaviridae
1: Adenoviridae, Hepadnaviridae, Heroesviridae, Papillomaviridae
2: Rhabdoviridae (viral RdRp L), Reoviridae (capping by VP3 and VP1),Togaviridae, Poxviridae
3: Orthomyxoviridae (cap cleavage of pre-mRNA in nucleus by Viral RdRp), Bunyavirus(N protein binds to cellular mRNA, degradation of mRNA in p bodies, protection of 5’ end and cap by N protein)
Name three principle strategies by which viruses achieve the maximisation of the coding capacity of their genomes and state one viral example for each of them.
- functional polycistronic mRNAs Roy’s sarcoma virus
- readthrough of stop codons Sendai-virus
- polyproteins Picornavirus
