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* 1. growth curve
The graph shows the replication of a virus. Why is it not the replication of a bacterium? Select all answers that apply.

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* 2. To search for an agent that causes a disease of tomato plants you grind up diseased leaves in buffer and filter it through a 0.2 micron filter. When the filtrate (what passes through the filter) is applied to the leaves of healthy plants, no disease is observed. How can this finding be explained? Select all answers that apply.

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* 3. All of us carry many different viruses throughout our daily lives. Why do these viruses cause no disease in humans? Check all answers that apply.

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* 4. Viruses may form plaques on cells that are non-susceptible and permissive.

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* 5. You count 10 plaques on a plaque assay plate made from a dilution of 10-7 and 0.1 ml of the dilution was plated on the cell monolayer. What is the virus titer in PFU/ml? Check all answers that apply. Note: 10e-1 means 10 to the first power, etc.

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* 6. You use 0.1 ml of the stock of virus which you titrated in question #5 to infect 1 million cells. What is the MOI? Select only one answer.

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* 7. If you did a growth curve at the MOI that you calculated in Question #6, what would you expect to observe? Select all answers that apply.

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* 8. Why are no infectious virus particles detected during the eclipse phase of a one-step growth cycle? Select all answers that apply.

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* 12. Referring to ViRa and SaSi from question #9, is infectious virus produced after transfection of SaSi cells with poliovirus RNA?

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* 13. Why must all RNA virus genomes encode an RNA-dependent RNA polymerase? Check all answers that apply.

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* 14. Why did Baltimore put mRNA at the center of his classification of viral genomes? Check all answers that apply.

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* 15. You have an RT-PCR test for SARS-CoV-2 done on a nasal swab and are told that the test is positive with a Ct value of 37. You have never had symptoms or signs associated with COVID-19. Which of the following arguments could be made against your being quarantined? Check all answers that apply.

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* 16. The simplest icosahedral capsid is built with 60 copies of a single protein. These are small particles, approximately 30 nm in diameter. How are larger capsids are built? Check all answers that apply.

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* 18. What two properties of virus particles allow them to be metastable? Check all answers that apply.

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* 20. When HIV-1 was first identified the T-cell receptor was shown to be the CD4 molecule on the cell surface. However introduction of the CD4 gene into a variety of cells did not lead to productive infection. What are explanations for this observation? Check all answers that apply.

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* 21. Viral membrane fusion be regulated to prevent this event from occurring in the wrong place. How is membrane fusion regulated? Check all answers that apply.

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* 22. Influenza virus mRNAs are shorter than the genomic RNAs from which they are made. What is the mechanism for production of full-length copies of the genomic (-) RNAs for incorporation into newly synthesized virus particles? Check all answers that apply.

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* 23. Some RdRp require a primer to initiate RNA synthesis. What types of primers may be used for RNA synthesis? Check all answers that apply.

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* 24. The palm domain of poliovirus RdRp contains a GDD motif. Changing D (Asp) to alanine produces an inactive polymerase that can no longer copy RNA templates because (check all answers that apply):

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* 25. A high particle-to-pfu ratio means: (one answer)

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* 26. The definition of mutation is: (check all answers that apply)

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* 28. Which ONE of the following statements about transcription of viral DNA templates is INCORRECT?

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* 29. Splicing marks mRNAs for export from the nucleus. Unspliced viral mRNAs may be exported by which of the following mechanisms? Choose all that apply.

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* 30. Which of the following is true of viral DNA replication?

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* 32. Replication of SV40 DNA initiates at a single ORI. How many leading and lagging strands are there?

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* 33. How is the 5’-end problem solved for viral DNA genomes? Check all that apply.

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* 36. Reverse transcription is a convoluted process during which the enzyme starts near the end of the template and switches template twice. The reason for this complexity is: (check all that apply)

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* 39. Coronavirus particles acquire an envelope by budding into the ERGIC. How do these enveloped particles leave infected cells without losing their membranes or lysing the host cell?

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* 40. The process by which viral nucleic acids are encapsidated is called genome packaging. Which of the following statements about genome packaging is INCORRECT?

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* 43. Which of the following statements about signal trans­duction in virus­ infected cells is INCORRECT?

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