Chapter 13

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Viruses are not composed of cells.

They cannot reproduce themselves outside a host.

Viruses use their own catabolic enzymes.

False: Viruses are obligatory intracellular parasites -- so they must have evolved after a suitable host cell had evolved. They multiply by using the host cell's synthesizing machinery to cause the synthesis of specialized elements that can transfer the viral nucleic acid to other cells.

biochemical tests

B.

False -- (Note the word ALL - just some). Some Quizlet Answers have this Just FYI From Textbook (see photo): However, the receptor sites of animal cells are proteins and glycoproteins of the plasma membrane. Moreover, animal viruses do not possess appendages like the tail fibers of some bacteriophages ... In many of the enveloped viruses, such as influenza virus, the attachment sites are spikes located on the surface of the envelope (see Figure 13.3b). As soon as one spike attaches to a host receptor, additional receptor sites on the same cell migrate to the virus. Attachment is completed when many sites are bound.

False. Those are terms used to describe the capsid. * Based on another Quizlet Question I found: Q.) Helical and icosahedral are terms used to describe the shapes of a virus A. Spike B. Capsomere C. Envelope D. Capsid E. Core Answer: D.) Capsid

Answer: has the same genetic information and ecological niche. From Textbook: The International Committee on Taxonomy of Viruses defines a viral species as a population of viruses with similar characteristics (including morphology, genes, and enzymes) that occupies a particular ecological niche.

Prophage. Careful here: Don't get fooled by the term "lysogeny" ... the textbook says: Alternatively, the circle can recombine with and become part of the circular bacterial DNA (the lysogenic cycle). The inserted phage DNA is now called a prophage. Note this is about "Genome" not DNA. DNA is about Lysogeny. Plus, the other trick in play here is all the verbs they use that start with "I" -- Integrated/Inserting are the different but interchangeable words. Later you will see they use "incorporated." You can see how close this is to what is said about "Lysogeny": Textbook: These lysogenic phages (also called temperate phages) may indeed proceed through a lytic cycle, but they are also capable of "incorporating" their DNA into the host cell's DNA to begin a lysogenic cycle. In lysogeny, the phage remains latent (inactive). The participating bacterial host cells are known as lysogenic cells. Tricky Bastards: Integrated/Inserting/Incorporating - all very similar. From Glossary: Prophage: Phage DNA inserted into the host cell's DNA. Lysogenic Cycle: Stages in viral development that result in the incorporation of viral DNA into host DNA. Lysogeny: A state in which phage DNA is incorporated into the host cell without lysis.

Exposure to UV light

The host cell dies during the lytic stage.

It is copied every time the host DNA replicates.

Penetration

Assembly

Biosynthesis

The virus would not be able to infect new hosts.

Phage DNA is incorporated into host cell DNA. See what I mean from earlier and the Question below: Lysogenic viral DNA integrating into the host genome is referred to as induction. a prophage. lytic. lysogeny. There it is what about Genome and Integrating, this question is about DNA and Incorporating.

The prophage makes the host cell immune to infection by other phages.

Immunity to reinfection by any phage.

E) It causes lysis of host cells.

True

The virus is causing the death of the infected cells in the patient.

The "host range" for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach. Correct. Attachment of the virus to the host cell (the first step in the viral life cycle) requires binding of complementary molecules on the virus and host cell.

Spikes are found on some viruses. They are very consistent in structure and can be used for identification. Correct. Some enveloped viruses have spikes, and they can be used for identification, such as the H and N spikes on the influenza virus.

During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome. Correct. During lysogeny, the viral genome is integrated into the host DNA. It is inactive at this time, and virus is not produced.

Viruses are not composed of cells.

They cannot reproduce themselves outside a host.

Viruses use their own catabolic enzymes.

Spikes are found on some viruses. They are very consistent in structure and can be used for identification. Correct: Some enveloped viruses have spikes, and they can be used for identification, such as the H and N spikes on the influenza virus.

True

False

True

They are found only on nonenveloped viruses.

biochemical tests

False

has the same genetic information and ecological niche.

C I modified the picture from the textbook instead of using the Mastering Pic.

phage DNA is incorporated into host cell DNA.

The prophage makes the host cell immune to infection by other phages.

The virus is causing the death of the infected cells in the patient.

1) In which of the following ways do viruses differ from bacteria? A) Viruses are filterable. B) Viruses are obligate intracellular parasites. C) Viruses don't have any nucleic acid. D) Viruses are not composed of cells. E) Viruses don't reproduce.

2) Which of the following statements provides the most significant support for the idea that viruses are nonliving chemicals? A) They are not composed of cells. B) They are filterable. C) They cannot reproduce themselves outside a host. D) They cause diseases similar to those caused by chemicals. E) They are chemically simple.

3) Which of the following statements about spikes is false? A) They are used for penetration. B) They are used for absorption. C) They may cause hemagglutination. D) They are found only on enveloped viruses. E) They are found only on nonenveloped viruses.

4) Which of the following is NOT used as a criterion to classify viruses? A) Biochemical tests B) Morphology C) Nucleic acid D) Size E) Number of capsomeres

5) Which of the following is NOT a method of culturing viruses? A) In laboratory animals B) In culture media C) In embryonated eggs D) In cell culture E) None of the above

6) Bacteriophages and animal viruses do NOT differ significantly in which one of the following steps? A) Adsorption B) Penetration C) Uncoating D) Biosynthesis E) Release

7) The definition of lysogeny is A) Phage DNA is incorporated into host cell DNA. B) Lysis of the host cell due to a phage. C) The period during replication when virions are not present. D) When the burst time takes an unusually long time. E) Attachment of a phage to a cell.

8) A viroid is A) A complete, infectious virus particle. B) A nonenveloped, infectious piece of RNA. C) A capsid without a nucleic acid. D) A provirus. E) An infectious protein.

9) In Figure 13.1, which structure is a complex virus? A) a B) b C) c D) d E) All of the above

10) In Figure 13.1, the structures illustrated are composed of A) DNA. B) RNA. C) DNA or RNA. D) Capsomeres. E) Capsids.

11) A clear area against a confluent "lawn" of bacteria is called a A) Phage. B) Pock. C) Cell lysis. D) Plaque. E) Rash.

12) Continuous cell lines differ from primary cell lines in that A) Viruses can be grown in continuous cell lines. B) Continuous cell lines always have to be reisolated from animal tissues. C) Continuous cell lines are derived from primary cell lines. D) Continuous cell lines can be maintained through an indefinite number of generations. E) Continuous cell lines are from human embryos.

13) Which of the following is necessary for replication of a prion? A) DNA B) DNA polymerase C) Lysozyme D) PSc E) RNA

14) A persistent infection is an infection in which A) The virus remains in equilibrium with the host without causing a disease. B) Viral replication is unusually slow. C) The disease process occurs gradually over a long period. D) Host cells are gradually lysed. E) Host cells are transformed.

15) 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.

16) Lysogeny can result in all of the following EXCEPT A) Immunity to reinfection by the same phage. B) Acquisition of new characteristics by the host cell. C) Immunity to reinfection by any phage. D) Transduction of specific genes. E) None of the above.

17) Which of the following would be the first step in biosynthesis of a virus with a - strand of RNA? A) Synthesis of DNA from an RNA template B) Synthesis of double-stranded RNA from an RNA template C) Synthesis of double-stranded RNA from a DNA template D) Transcription of mRNA from DNA E) Synthesis of DNA from a DNA template

18) An infectious protein is a A) Bacteriophage. B) Prion. C) Retrovirus. D) Viroid. E) Papovavirus.

19) An envelope is acquired during which of the following steps? A) Penetration B) Adsorption C) Uncoating D) Biosynthesis E) Release

20) 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.

21) An example of a latent viral infection is A) Subacute sclerosing panencephalitis. B) Cold sores. C) Influenza. D) Smallpox. E) Mumps.

22) The most common route of accidental AIDS transmission to health care workers is A) Mouth to mouth. B) Fecal-oral. C) Needlestick. D) Aerosol. E) Environmental surface contact.

23) Assume you have isolated an unknown virus. It is a single-stranded RNA, enveloped virus. To which group does it most likely belong? A) Herpesvirus B) Picornavirus C) Retrovirus D) Togavirus E) Papovavirus

24) To which group does a small, nonenveloped single-stranded RNA virus most likely belong? A) Herpesvirus B) Picornavirus C) Retrovirus D) Togavirus E) Papovavirus

25) The most conclusive evidence that viruses cause cancers is provided by A) Finding oncogenes in viruses. B) The presence of antibodies against viruses in cancer patients. C) Cancer following injection of cell-free filtrates. D) Treating cancer with antibodies. E) Some liver cancer patients having had hepatitis.

26) Bacteriophages derive all of the following from the host cell EXCEPT A) Lysozyme. B) tRNA. C) Amino acids. D) Nucleotides. E) A.T.P.

27) Generalized transduction differs from specialized transduction in that generalized transduction A) Kills the host. B) Transfers DNA from one cell to another. C) Transfers specific DNA. D) Involves lysogeny. E) Lyses the host cell.

28) Generally, in a DNA-containing virus infection, the host animal cell supplies all of the following EXCEPT A) RNA polymerase. B) Nucleotides. C) DNA polymerase. D) tRNA. E) All of the above are supplied by the host animal cell.

29) Put the following in the correct order for DNA-virus replication: 1-Maturation; 2-DNA synthesis; 3-Transcription; 4-Translation. A) 1, 2, 3, 4 B) 2, 3, 4, 1 C) 3, 4, 1, 2 D) 4, 1, 2, 3 E) 4, 3, 2, 1

30) A viral species is a group of viruses that A) Have the same morphology and nucleic acid. B) Have the same genetic information and ecological niche. C) Infect the same cells and cause the same disease. D) Can't be defined.

31) Viruses that have reverse transcriptase are in the A) Retroviridae and Picornaviridae. B) Herpesviridae and Retroviridae. C) Hepadnaviridae and Retroviridae. D) Bacteriophage families. E) Influenzavirus.

32) DNA made from an RNA template will be incorporated into the virus capsid of A) Retroviridae. B) Herpesviridae. C) Hepadnaviridae. D) Bacteriophage families. E) Influenzavirus.

33) 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.

34) Approximately how many virus particles could fit along a 1-millimeter line? A) 2 B) 20 C) 200 D) 20,000 E) 2,000,000

35) Some viruses, such as human herpesvirus 1, infect a cell without causing symptoms; these are called A) Latent viruses. B) Lytic viruses. C) Phages. D) Slow viruses. E) Unconventional viruses.

37) 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)? A) a B) b C) c D) d E) e

37) Assume a patient has influenza. During which time (on the graph in Figure 13.2) would the patient show the symptoms of the illness? A) a B) b C) c D) d E) e

38) The following steps occur during multiplication of herpesviruses. What is the third step? A) Attachment B) Biosynthesis C) Penetration D) Release E) Uncoating

39) The following steps occur during multiplication of retroviruses. What is the fourth step? A) Synthesis of double-stranded DNA B) Synthesis of + RNA C) Attachment D) Penetration E) Uncoating

40) 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 A) Host enzymes. B) Prions. C) Reverse transcriptase. D) Transduction. E) None of the above

41) Which one of the following steps does NOT occur during multiplication of a picornavirus? A) Synthesis of + strands of RNA B) Synthesis of - strands of RNA C) Synthesis of viral proteins D) Synthesis of DNA E) None of the above

42) Which of the following is most likely a product of an early gene? A) Capsid proteins B) DNA polymerase C) Envelope proteins D) Spike proteins E) Lysozyme

43) Most RNA viruses carry which of the following enzymes? A) DNA-dependent DNA polymerase B) Lysozyme C) RNA-dependent RNA polymerase D) Reverse transcriptase E) ATP synthase

44) The following steps occur during biosynthesis of a + strand RNA virus. What is the third step? A) Attachment B) Penetration and uncoating C) Synthesis of - strand RNA D) Synthesis of + strand RNA E) Synthesis of viral proteins

45) What contributes to antigenic shift in influenza viruses? A) Worldwide distribution B) Segmented genome C) Attachment spikes D) Ease of transmission E) Different subtypes