Virus

In which stage does formation of mature viruses occur?

Assembly

Which of the following is true concerning a lysogenic viral replication cycle?

During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.

Which of the following events might trigger induction of a temperate bacteriophage?

Exposure to UV light

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

False

Glycoprotein spikes are found on the capsids of all viruses. T or F

False

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

False

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

False

Which of the following statements is NOT true of lysogeny?

It causes lysis of host cells.

Which of the following statements concerning viruses is true?

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.

Which of the following statements about viruses is FALSE?

Viruses use their own catabolic enzymes.

Lysogeny can result in all of the following EXCEPT

immunity to reinfection by any phage.

Lysogenic viral DNA which has integrated into the host genome is referred to as

a prophage.

What contributes to antigenic shift in influenza viruses?

a segmented genome

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.

Bacteriophages derive all of the following from the host cell EXCEPT

lysozyme.

Which of the following places these items in the correct order for DNA-virus replication? 1. Maturation 2. DNA synthesis 3. Transcription 4. Translation

2; 3; 4; 1

The host DNA is usually degraded during which stage?

Biosynthesis

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

DNA polymerase.

What is the fate of the prophage during the lysogenic stage?

It is copied every time the host DNA replicates.

In which stage is the viral DNA introduced into the cell?

Penetration

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

Plaque

Which statement concerning viral structure is true?

Spikes are found on some viruses. They are very consistent in structure and can be used for identification.

What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?

The host DNA integrates, with the prophage, into the new recipient chromosome.

How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?

The host cell dies during the lytic stage.

How does specialized transduction differ from regular lysogeny?

The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.

Which of the following statements is FALSE?

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

How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population?

The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.

What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?

The virus would not be able to infect new hosts.

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 are not composed of cells.

How are viruses different from eukaryotic cells?

They require a host in order to reproduce.

What is the function of the structural elements of a virus?

To package and protect the viral genome

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

True

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

True

Which of the following is true of viroids?

Viroids are short pieces of naked RNA.

How do all viruses differ from bacteria?

Viruses are not composed of cells.

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.

Oncogenic viruses

cause tumors to develop.

An example of a latent viral infection is

cold sores.

The definition of lysogeny is

phage DNA is incorporated into host cell DNA.

A virus's 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

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

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