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45 terms

Chapter 13

Viruses, Viroids, and Prions Jen Mc
STUDY
PLAY
In which of the following ways do viruses differ from bacteria?
Viruses are not composed of cells
Which of the following statements provides the most significant support for the idea that viruses are nonliving chemicals?
They cannot reproduce themselves
Which of the following statements about spikes is false?
They are used for penetration
Which of the following is NOT used as a criterion to classify viruses?
Biochemical tests
Which of the following is NOT a method of culturing viruses
In culture media
Bacteriophages and animal viruses do NOT differ significantly in which one of the following steps?
Biosynthesis
The definition of lysogeny is
Phage DNA is incorporated into host cell DNA
A viroid is
A nonenveloped, infectious piece of RNA
In figure 13.1, which structure is a complex virus
B
looks like a rocket with legs
In figure 13.1, the structures illustrated are composed of
Capsomeres
A clear area against a confluent "lawn" of bacteria is called a
Plaque
Continuous cell lines differ from primary cell lines in that
Continuous cell lines can be maintained through an indefinite number of generations
Which of the following is necessary for replication of a prion?
pSc
A persistent infection is an infection in which
The disease process occurs gradually over a long period
Which of the following statements is false?
A. A prophage is phage DNA inserted into a bacterial chromosome
B. A prophage can pop out of the chromosome
C. Prophage genes are represented by a repressor protein coded for by the prophage
D. A prophage may result in new properties of the host cell
E. The prophage makes the host cell immune to infection by other phages
The prophage makes the host cell immune to infection by other phages
Lysogeny can result in all of the following EXCEPT
Immunity to reinfection by any phage
Which of the following would be the first step in biosynthesis of a virus with a - strand of RNA
Synthesis of double-stranded RNA from an RNA template
An infectious protein is a
Prion
An envelope is acquired during which of the following steps?
Release
Which of the following contributes to the difficulty in establishing the etiology of cancer?
A. Most viral particles can infect cells without inducing cancer
B. Cancer may not develop until long after infection
C. Cancers do not seem to be contagious
D. Viruses are difficult to observe
E. All of the above
All of the above
An example of a latent viral infection is
Cold sores
The most common route of accidental AIDS transmission to health care workers is
Needlestick
Assume you have isolated an unknown virus. It is a single-stranded RNA, enveloped virus. To which group does it most likely belong?
Togavirus
To which group does a small, nonenveloped single-stranded RNA virus most likely belong?
Picornavirus
The most conclusive evidence that viruses can cause cancers is provided by
Cancer following injection of cell-free filtrates
Bacteriophages derive all of the following from the host cell EXCEPT
Lysozyme
Generalized transduction differs from specialized transduction in that generalized transduction
Transfers specific DNA
Generally, in a DNA-containing virus infection, the host animal cell supplies all of the following EXCEPT
DNA polymerase
Put the following in the correct order for DNA-virus replication
1-Maturation
2-DNA synthesis
3-Transcription
4-Translation
2,3,4,1
DNA synthesis, Transcription, Translation, Maturation
A viral species is a group of viruses that
Have the same genetic information and ecological niche
Viruses that have reverse transcriptase are in the
Hepadnaviridae and Retroviridae
(Hepatitis and HIV)
DNA made from an RNA template will be incorporated into the virus capsid of
Hepadnaviridae
Which of the following statements about viruses is false?
A. Viruses contain DNA or RNA but never both
B. Viruses contain a protein coat
C. Viruses use the anabolic machinery of the cell
D. Viruses use their own catabolic enzymes
E. Viruses have genes
Viruses use their own catabolic enzymes
Approximately how many virus particles could fit along a 1 millimeter line?
20,000
Some viruses, such as human herpesvirus 1, infect a cell without causeing symptoms; these are called
Latent viruses
Assume a patient had chickenpox (human (herpesvirus 3) as a child. Which line on the graph in Figure 13.2 would show the number of viruses present in this person as a 60 year old with shingles (human herpesvirus 3)?
E
Latent
Assume a patient has influenza. During which time (on the graph in Figure 13.2) would the patient show the symptoms of the illness?
C
Acute
The following steps occur during multiplication of herpesviruses. What is the third step?
Uncoating
The following steps occur during multiplication of retroviruses. What it the fourth step?
Synthesis of double-stranded DNA
Nontoxic strains of Vibrio cholerae can become toxic when they are in the human intestine with toxic strains of bacteria. This suggests that the toxin genes are acquired by
Transduction
Which of the following steps does NOT occur during multiplication of a picornavirus (single stranded RNA)?
Synthesis of DNA
Which of the following is most likely a product of an early gene?
DNA polymerase
Most RNA viruses carry which of the following enzymes?
RNA-dependent RNA polymerase
The following steps occur during biosynthesis of a + strand RNA virus. What is the third step?
Synthesis of a - strand RNA
What contributes to antigenic shift in influenza viruses?
Segmented genome