Chapter 24 (actually chapter 17)

Which of the following nucleic acids make(s) up viral genomes?

DNA or RNA

Which of the three types of viruses shown in the figure above would you expect to include glycoproteins as part of their overall structure? (picture one)

II only

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

The phage genome replicates along with the host genome.

Which of the following responses correctly lists the order of events in a generalized viral replicative cycle?

The virus enters the cell, host enzymes replicate the viral genome, enzymes transcribe the viral genome into mRNA

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. Which of the following would be expected to occur?

The plants would develop the typical symptoms of TMV infection.

Which of the following statements correctly describes one difference between vertical and horizontal transmission of plant viruses?

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.

Most molecular biologists think that viruses originated from naked bits of cellular nucleic acid. Which of the following observations supports this theory?

Viral genomes are usually similar to the genome of the host cell.

Which of the following statements accurately describes plant virus infections?

They are spread via the plasmodesmata.

Which of the following statements correctly describes viruses?

They cannot reproduce without a host cell.

Which of the following statements correctly describes adenoviruses?

They contain DNA surrounded by a capsid.

Why are viruses called obligate intracellular parasites?

They must use a host cell's nucleotides for transcription and replication. They must use a host cell's ribosomes to synthesize proteins. They must use a host cell's amino acids to synthesize proteins. They must use a host cell's metabolic enzymes and pathways to obtain energy.

Why are retroviruses considered a special class of viruses?

They transcribe RNA to DNA using reverse transcriptase.

Which of the three types of viruses shown in the figure above would you expect to include a capsid(s) as part of their overall structure? (picture 1)

all three

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

genetic material composed of nucleic acid

Which of the following processes can be effective in preventing the onset of viral infection in humans?

getting vaccinated

In the figure above, at the arrow marked II, what enzyme is being utilized? (picture 2)

host cell DNA polymerase

RNA viruses require their own supply of certain enzymes because

host cells lack enzymes that can replicate the viral genome

Which of the following characteristics determine a virus's host range?

the proteins on its surface and that of the host

In the figure above, when new viruses are being assembled during the step labeled IV, how is the assembly of the new virus particles completed? (picture 2)

the proteins self-assemble

In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA, referred to as the Baltimore requirements. The table below shows the results of testing five viruses (A−−E) for nuclease sensitivity, the ability of the viral genome to act as an mRNA, and the presence (+) or absence (-) of each virus's own polymerase.

A

Which of the following statements correctly describes one characteristic of the lytic cycle of viral replication?

A large number of phages are released at a time.

What happens first when a phage infects a bacterial cell and is going to enter a lysogenic cycle?

Linear DNA circularizes

Why do RNA viruses tend to have unusually high rates of mutation?

Replication of their genomes does not involve correcting errors in genome replication.

How do antiviral drugs help to treat viral infections?

They interfere with viral replication

What describes the best predictor of how much damage a virus causes?

ability of the infected cell to undergo normal cell division

The nucleic acid of a virus particle is enclosed in a protein coat. What is this protein coat called?

capsid

Some people who have had a herpesvirus-mediated cold sore or genital sore may have flare-ups for the rest of their life. Why does this occur?

copies of the herpesvirus genome remaining as mini-chromosomes in some host cell nuclei

HIV uses which of the following processes to synthesize a DNA strand using its RNA genome as a template?

reverse transcription