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Exam 19: Viruses

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Question 21

Multiple Choice

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Which of the following processes can viruses carry out?

A) They can manufacture their own ATP, proteins, and nucleic acids.
B) They can use the host cell to copy themselves and make viral proteins.
C) They can use the host cell to copy themselves and then synthesise their own proteins inside the viral capsid.
D) They can metabolise food and produce their own ATP.

E) B) and D)
F) All of the above

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Question 22

Multiple Choice

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Why do RNA viruses appear to have higher rates of mutation?

A) RNA nucleotides are more unstable than DNA nucleotides.
B) Replication of their genomes does not involve proofreading.
C) RNA viruses can incorporate a variety of nonstandard bases.
D) RNA viruses are more sensitive to mutagens.

E) C) and D)
F) All of the above

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Question 23

Multiple Choice

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Which of the following types of viral genomes could be transcribed using reverse transcriptase?

-In the figure, at the arrow marked II, what enzyme is being utilised?

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV) . 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 the mixture?

Cells were infected with approximately 1,000 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 millilitre of culture was determined. -Using the data in the figure, how long does it take for virus B to go through one lytic cycle?

The virus genome and viral proteins are assembled into virus particles during which of the following parts of the reproductive cycle?

Some viruses can be crystallised and their structures analysed. One such virus is yellow mottle virus, which infects beans. This virus has a single-stranded RNA genome containing about 6,300 nucleotides. Its capsid is 25-30 nm in diameter and contains 180 identical capsomeres. If the yellow mottle virus begins its infection of a cell by using its genome as mRNA, which of the following would you expect to be able to measure when analysing the reproduction of this virus?

The herpesviruses are important enveloped DNA viruses that cause disease in vertebrates and in some invertebrates such as oysters. Some of the human forms are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV) , causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can later reactivate, replicate again, and infect others. In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell-surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty". Which of the following statements best fits these observations?

Why do scientists consider HIV to be an 'emerging virus'?

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

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 are the practical consequences of these findings?

What is the function of reverse transcriptase in retroviruses?

In 2009, a flu pandemic was believed to have originated when viral transmission occurred from pig to human, thereby earning the designation "swine flu". Although pigs are thought to have been the breeding ground for the 2009 virus, sequences from bird, pig and human viruses were all found within this newly identified virus. What is the most likely explanation of why this virus contained sequences from bird, pig and human viruses?

Which of the following statements accurately describes the lysogenic cycle of lambda (λ) phage?

Which of the following statements correctly describes a difference between viruses and prions?

A virus consisting of a single strand of RNA, which is reverse transcribed into complementary DNA, is referred to as a ________.

Which of the following statements supports the argument that viruses are nonliving?

-Which of the three types of viruses shown in the figure would you expect to include a capsid(s) ?

What is the difference between an epidemic and a pandemic?