Exam 33: Viruses

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. We expect that the plants would ________.

The first class of drugs developed to treat AIDS, such as AZT, were known as reverse transcriptase inhibitors. They worked because they ________.

You have isolated a newly discovered virus and are attempting to characterize it. You begin with its genome. You first isolate the virion-producing mRNA from cultured cells infected with the virus. When you compare this mRNA to the viral genome, you find that they are complementary. What does this tell you?

-In the accompanying figure, at the arrow marked II, what enzyme(s) are being utilized?

Viruses use the host'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 into DNA. How can these types of viruses infect humans, when human cells cannot perform a particular role that the virus requires?

Some viruses can be crystallized and their structures analyzed. One such virus is yellow mottle virus, which infects beans. This virus has a single-stranded RNA genome containing about 6300 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?

-In the figure, when new viruses are being assembled at the point marked IV, what mediates the assembly?

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

When people die from HIV infections, it is usually because they ________.

Which of the following could use reverse transcriptase to transcribe its genome?

Why do scientists consider HIV to be an emerging virus?

Use the accompanying figure and information to answer the question(s) below. -Using the data in the figure, how long does it take for virus B to go through one lytic cycle?

Which of the following characteristics, structures, or processes is common to bacteria and viruses?

Viruses ________.

The virus genome and viral proteins are assembled into virions (virus particles) during ________.

The HIV protease has been the target of several anti-HIV medications called protease inhibitors. This antiviral strategy is possible because protease inhibitors ________.

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

What is the difference between an epidemic and a pandemic?

Use the accompanying figure and information to answer the question(s) below. -Using the data in the figure, how long does it take for virus A to go through one lytic cycle?

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