Virology –Midterm vA, 22 April 2013:
1. Which of the following genomic nucleic acids are only found in viruses? a. dsDNA b. dsRNA c. ssDNA d. ssRNA e. B, C and D 2. About what percent of the human genome is indisputably viral? a. 1 b. 2 c. 5 d. 10 e. 50 3. Viruses were first discovered (and named as such) because they : a. could not be grown b. were very small c. were alive d. ate bacteria e. C and D 4. Phage therapy is to : a. Use a virus to kill a virus b. Use viruses to kill cancer cells c. Use viruses to kill bacteria d. Perform gene therapy e. Eat probiotics 5. What is probably the main reason to NOT use animals for determining virus counts: a. Mice are cute b. High Cost c. Reproducibility d. Study pathogenesis e. Fast 6. Incubation is critical in a plaque assay because: a. Viruses must bind to host cells b. Viruses must release their genome c. Viruses must undergo one round of replication d. Viruses must undergo many rounds of replication e. The host cells must be able to move 7. If you have 10 plaques on a plate after plating 1ml of a 10-7 dilution in a plaque assay your original virus titer is : a. 10-6 PFU/ml b. 106 PFU/ml c. 10-7 PFU/ml d. 107 PFU/ml e. 108 PFU/ml 8. Which of the following is a major drawback of the hemagglutination assay? a. It is slow b. It is expensive c. It is not quantitative 9.
Key VERSION (A)
d. It says nothing about virus infectivity e. It is very hard to perform In order to determine what percentage of cells in a population are infected by 1 and only 1 virus, you need to know a. The PFU b. How many viruses you have c. How many cells you have d. The gaussian distribution e. B and C The host range of viruses is also known as : a. Hemagglutination b. Tropism c. Virion binding d. Decapsidation e. Virion uncoating How many different classes of viruses are there according to Baltimore? a. 1 b. 2 c. 4 d. 6 e. 8 Which kinds of viruses need genome replication before translation can take place? a. Plus strand RNA viruses b. Negative strand RNA viruses c. Double stranded DNA viruses d. Double stranded RNA viruses e. All but B Which of the following techniques for virus structure determination has the highest resolution: a. Negative stain b. Thin section c. Cryo-electron microscopy d. X-ray crystallography e. A and B The simplest of icosahedrally symmetric viruses have capsid proteins with __ different amino acid sequence(s) in the virion. a. 1 b. 3 c. 20 d. 60 e. 180 A virus with icosahedral quasisymmetry with an “h” of 2 and “k” of 0 has how many coat proteins in its capsid? a. 60 b. 120 c. 180 d. 240 e. 300
16. Polio said to have pT3 symmetry because a. it has 60 subunits in the structure b. the coat protein has a beta barrel fold c. It has 3 different major coat proteins d. It encapsidates positive strand RNA e. It is not icosahedrally symmetric 17. The capsids of the largest known viruses seem to have : a. Helical symmetry b. Iscosahedral symmetry c. Appears to be derived from icosahedral symmetry d. Appears to be derived from heilcal symmetry e. Apparently no symmetry 18. The majority of the amino acids of most virus envelope proteins in mature enveloped virions is : a. Outside the envelope b. In the envelope membrane c. Inside the envelope d. Composed of lysines and arginines e. Composed of glutamates and aspartates 19. Which of the following amino acids are likely to be present in fusion peptides? a. Lysine and arginine b. Glutamate and Aspartate c. Glutamine and Asparagine d. Cysteine and Methionine e. Leucine, isoleucine and valine 20. What happens to influenza hemagglutinin HA0 to become HA1 and HA2? a. It binds to sialic acid b. It becomes trimeric c. It is proteolyzed d. It has a large conformational change e. It is translated 21. RNA viruses mostly replicate in the nucleus because a. Precursors are available b. The replicases are there c. Translation takes place in the nucleus d. The RNA is transported through the nuclear pore e. The pH...
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