Exam 19: Viruses

Use the following information to answer the following questions. In 1971,David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA. The table below shows the results of testing five viruses for nuclease specificity,the ability of the virus to act as an mRNA,and presence (+)or absence (-)of its own viral polymerase. -Given Baltimore's scheme,a positive sense single-stranded RNA virus such as the polio virus would be most closely related to which of the following?

Which of the following is characteristic of the lytic cycle?

Use the following information to answer the questions below. Some viruses can be crystallized and their structures analyzed.One such virus is Desmodium,or yellow mottle virus,which infects beans.This is a member of the tymovirus group and has a single-stranded RNA genome of ~6300 nucleotides.Its virion is 25-30 nm in diameter,and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere,which has icosahedral symmetry with 20 facets. -How many nucleotides of the genome would you expect to find in one capsid?

Use the following figure and information to answer the question(s)below. Cells were infected with approximately 1000 copies of either virus A or virus B at the 0 time point.At five-minute intervals,a sample of the virus and cell mixture was removed.The intact cells were removed from the sample,and the number of viruses per milliliter of culture was determined. -Using the data in the figure above,how long does it take for virus B to go through one lytic cycle?

How can viruses infecting humans ensure their replication,when the human cells cannot perform the replication the viruses require?

Which of the following human diseases is caused by a virus that requires reverse transcriptase to transcribe its genome inside the host cell?

What is the main structural difference between enveloped and nonenveloped viruses?

Will treating a viral infection with antibiotics affect the course of the infection?

Use the following figure to answer the questions below. -In the figure,at the arrow marked II,what enzyme(s)are being utilized?

Which of the following is the best predictor of how much damage a virus causes?

Viral envelopes can best be analyzed with which of the following techniques?

The difference between vertical and horizontal transmission of plant viruses is that

When is the virus genome and viral proteins assembled into virions?

The spread of viral disease in a human population occurs through which means?

Antiviral drugs that have become useful are usually associated with which of the following properties?

The country or region hit hardest during the outbreak of SARS in 2002-2003 was

The first class of drugs developed to treat AIDS,such as AZT,were known as reverse transcriptase inhibitors.Why did they work?

Evidence suggests that factors which contribute towards the virulence of E.coli strain O157:H7,a bacterial strain reported to cause 2,100 hospitalizations in the US annually,are caused by genes from a virus that infects bacteria.Considering this evidence,which statement most likely explains how the O157:H7 population acquired the genetic variation that distinguishes the strain from harmless E.coli strains,such as those that reside in our intestines?

What is a population of viruses with similar characteristics called?

To make a vaccine against mumps,measles,or rabies,which type of viruses would be useful?