Quiz 1 Chapter 19
What is difference between an epidemic and pandemic?
An epidemic is restricted to a local region, pandemic is global.
What is the function of reverse transcriptase in retroviruses?
It uses viral RNA as a template for DNA synthesis.
What is the function of reverse transcription in retroviruses?
It uses viral RNA as a template for DNA synthesis.
Viral genomes vary greatly in size and may include from four genes to several hundred genes. WHich of the following viral features is most apt to correlate with the size of the genome.
RNA versus DNA genome.
A virus consisting of a single strand of RNA, which is reverse transcribed into complementary DNA, is referred to as a...
Retrovirus
The virus genome and viral proteins are assembled into virus particles during which of the following parts of the reproductive cycle?
The lytic cycle only
Which of the following statements accurately describes the lysogenic cycle of lambda phage?
The phage genome is integrated in the host chromosome where it is replicated along with the host genome.
Evidence suggests that factors that contribute towards the virulence of E.coli strain O157: H7, a bacterial strain reported causing several food poisonings deaths are caused by genes from a virus that infects bacteria. Considering this evidence, which of the following statements most likely explains how the population acquired the genetic variation that
The virus infected the bacterium, and allowed the bacterial population to replicate with a cop of the phage in each new bacterium.
Which of the following statements correctly describes vaccines and how they help prevent viral infection
Vaccines are inactive versions of a virus that stimulate an immune reaction in a person.
The difference between the vertical and horizontal transmission of plant viruses is that vertical transmission is
transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant.
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 A to go through one lytic cycle? Using the data in Figure Y, how long does it take for virus A to go through one lytic cycle?
45 minutes
Which of the following characteristics is typical of the lytic cycle of a bacteriophage?
A large number of phages are released at a time
Which of the following characteristics, structure, or processes is common to both bacteria and viruses.
Genetic Material composed of nucleic acids.
Which of the three types of viruses shown would you expect to include glycoproteins
I and II only
If you already know that the infectious agent was either a virus or prion, which methods listed above would allow you to distinguish from the two possibilities.
I only
Which of the three types of viruses shown above do you expect to include a capsid(s)?
I,II,III
You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope III. culturing the substance by itself on nutritive medium, away from any plant cells IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between these two possibilities?
II or III
Will treating a viral infection with antibodies affect the course of the infection?
No antibiotics work by inhibiting enzymes specific to bacteria. Antibiotics have no effect on eukaryotic or virally encoded enzymes.
A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 DNA. The new phages produced would have.
T4 protein and T4 DNA.
The first class of antiviral drugs developed to treat HIV infections, such as AZT, were known as reverse transcriptional inhibitors. How did these drugs carry out their function?
The drug molecules bonded to the viral reverse transcriptase enzyme, thus preventing the virus from making DNA copy of its RNA genome.
HIV is inactivated in the laboratory after a few minutes of sitting at room temperature, but the flu virus is still active after sitting for several hours. What is the practical consequences of these findings.
The flu can be transmitted more easily from person to person than HIV.
A researcher lyses a cell that contains nucleic acids molecule and capsomeres of tobacco mosaic virus. The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. What would you expect to happen to the plants that were sprayed with with the mixture?
The plants would develop the typical symptoms of TMV infection.
Viruses use the host cell's machinery to make copies of themselves. However, some human viruses require a type of replication that humans do not normally have. For example, humans normally do not have the ability to convert Rna to DNA. How can these types of viruses infect humans, when human cells cannot perform a particular role that the virus requires?
The viral genome codes for specialized enzymes not found in the host cells.
Which of the following statements supports the argument that viruses are nonliving?
They do not carry out metabolic processes
Which of the following statements correctly describes a difference between viruses and prions
Viruses generally cause disease symptoms quickly, whereas prions generally take many years to cause disease symptoms.
In Figure Z. above, when new viruses are being assembled at the point marked IV, what mediates the assembly?
no mediator is required; the new viruses self-assemble.
The host range of a virus is determined by
the proteins on its surface and that of the host
