micro ch 13

Which of the following is NOT used as a criterion to classify viruses?

biochemical tests

Bacteriophages and animal viruses do NOT differ significantly in which one of the following steps?

biosynthesis

The mechanism whereby an enveloped virus leaves a host cell is called

budding

The most conclusive evidence that viruses cause cancers is provided by

cancer following injection of cell-free filtrates.

Oncogenic viruses

cause tumors to develop

An example of a latent viral infection is

cold sores

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 NOT utilized to culture viruses?

culture media

A viral species is a group of viruses that

has the same genetic information and ecological niche.

A viroid is a(n)

infectious piece of RNA without a capsid.

Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves

injection of naked nucleic acid into the host cell.

Some viruses, such as human herpesvirus 1, infect a cell without causing symptoms. These are called

latent viruses

The definition of lysogeny is

phage DNA is incorporated into host cell DNA.

A clear area against a confluent "lawn" bacteria is called a

plaque.

A virus' ability to infect an animal cell depends primarily upon the

presence of receptor sites on the cell membrane.

An infectious protein is a

prion

An envelope is acquired during which of the following steps?

release

The following steps occur during biosynthesis of a + strand RNA virus. What is the third step?

synthesis of - strand RNA

Which one of the following steps does NOT occur during multiplication of a picornavirus?

synthesis of DNA

The following steps occur during multiplication of retroviruses. Which is the fourth step?

synthesis of double-stranded DNA

Which of the following would be the first step in biosynthesis of a virus with a - (minus) strand of RNA?

synthesis of double-stranded RNA from an RNA template

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 repressed 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. Answer: E

Which of the following statements is NOT true of lysogeny?

A) It can give infected pathogens the genetic information for toxin production. B) Prophage is inserted into the host genome. C) Lytic cycle may follow lysogeny. D) It is a "silent" infection; the virus does not replicate. E) It causes lysis of host cells. Answer: E

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) specialized transduction E) phage conversion. Answer: C

Bacteriophages derive all of the following from the host cell EXCEPT

A) lysozyme. B) tRNA. C) amino acids. D) nucleotides. E) ATP. Answer: A

Which of the following is most likely a product of an early gene?

DNA polymerase

Generally, in an infection caused by a DNA-containing virus, the host animal cell supplies all of the following EXCEPT

DNA polymerase.

Most RNA viruses carry which of the following enzymes?

RNA-dependent RNA polymerase

Which of the following places these items in the correct order for DNA-virus replication?

1. DNA synthesis 2. Transcription 3. Translation 4. Maturation

A viroid is a completely developed infectious agent composed of nucleic acid and surrounded by a capsid.

FALSE

Binomial nomenclature is used to name viruses.

FALSE

Glycoprotein spikes are found on the capsids of all viruses.

FALSE

Helical and icosahedral are terms used to describe the shapes of a virus envelope.

FALSE

Viruses are the only known infectious agents that are obligatory intracellular parasites.

FALSE

Viruses that utilize reverse transcriptase belong to the virus families

Hepadnaviridae and Retroviridae.

DNA made from an RNA template will be incorporated into the virus capsid of

Hepadnaviridae.

________ were first identified in cancer-causing viruses and can induce ________ in infected cells.

Oncogenes; transformation

Which of the following is necessary for replication of a prion?

PrPSc

A segmented genome can result in antigenic shift.

TRUE

Dogs do not get measles because their cells lack the correct receptor sites for that virus.

TRUE

Most drugs that interfere with viral multiplication also interfere with host cell function.

TRUE

Positive sense RNA strands of viruses are treated like mRNA inside the host cell.

TRUE

The basic mechanism of viral multiplication is similar for all viruses.

TRUE

A lytic virus has infected a patient. Which of the following would best describe what is happening inside the patient?

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

Which of the following statements about viral spikes is FALSE?

They are found only on nonenveloped viruses.

Which of the following statements provides the most significant support for the idea that viruses are nonliving chemicals?

They cannot reproduce themselves outside a host.

How do all viruses differ from bacteria?

Viruses are not composed of cells.

Which of the following statements about viruses is FALSE?

Viruses use their own catabolic enzymes.

What contributes to antigenic shift in influenza viruses?

a segmented genome

A persistent infection is one in which

the disease process occurs gradually over a long period.

Assume you have isolated an unknown virus. This virus has a single, positive sense strand of RNA, and possesses an envelope. To which group does it most likely belong?

togavirus

The following steps occur during multiplication of herpesviruses. Which is the third step?

uncoating