In what ways do viruses differ from other pathogens?

Viruses lack cytoplasm & organelles

The outermost layer of a virion fulfills which of the following functions of the virus?

both protection & recognition

A n ______ is a virus that infects bacterial cells.

bacteriophage

Which of the following is a characteristic by which viruses are classified?

type of nucleic acid

Host specificity of a virus is due to

interactions between viral and cellular surface molecules

Which of the following is primarily responsible for the shape of a virion?

the capsid

How are fungal viruses different from viruses that infect other organisms?

they have no extracellular state.

Which of the following infectious particles do NOT have protein in their structure?

viroids

Which of the following may occur in a lysogenic infection, but not a latent one?

The inserted viral DNA may leave the host DNA

Which of the following statements regarding virus taxonomy is true?

Some virus family names are derived from the name of an important member of the family.

Which of the following statements comparing virus classification and taxonomy of organisms is true?

Genus and specific epithet are used in both classification systems.

Which of the following places stages of a lytic replication cycle in order, from earliest to latest stages?

III, V, I, II, IV

Which of the following is associated with the attachment of a bacteriophage to a bacterial cell?

random collisions, chemical attractions, and receptor specificity

The enzyme lysozyme is critical for which of the stages of a bacteriophage T4 infection cycle?

entry and release

Which means of entry into host cells is common to both some animal viruses and bacteriophage T4?

direct penetration

Which of the following events occurs in the lytic cycle of bacteriophage T4 infection but NOT in the lysogenic cycle?

digestion of host DNA

Why is lysogen advantageous to a bacteriophage?

The genetic material of the bacteriophage is amplified many times over that seen in a lytic phage.

Which of the following agents is capable of inducing conversion of a prophage to the lytic cycle?

both UV light and X-rays

Zones of clearing in cell cultures that are the result of virus infection are called plaques. Sometimes "cloudy plaques" are seen on bacteria cultures infected with bacteriophage. What type of viral infection might cause this appearance?

lysogenic

Which of the following is matched Incorrectly?

adenovirus; membrane fusion

Reverse transcriptase is associated with which of the following?

retroviruses

The genome of which of the following types of animal virus can act directly as mRNA?

+ssRNA viruses

Which of the following types of animal virus requires RNA-dependent RNA transcriptase to be replicated?

-ssRNA viruses

In contrast to most dsDNA animal viruses, the poxviruses replicate solely in the cytoplasm of the host cell. this fact implies that the viral genome may encode

a DNA polymerase

Which of the following membranes can give rise to a viral envelope?

the nuclear and cytoplasmic membranes and the endoplasmic reticulum

A cell is infected with a virus carrying an oncogene sequence in its genome. What process may occur if the oncogenes expressed in the infected cell?

neoplasia

How is the HIV provirus different from a lambda-phage prophage?

The HIV provirus is integrated permanently into the host cell's DNA

Which of the following laboratory procedures is used for culturing animal viruses in the laboratory?

both cell cultures and embryonated eggs

One mechanism by which viruses may cause cancer is to interrupt the genetic regulatory sequences of repressor proteins. which of the following types of viruses is most likely to be involved in causing cancer by this mechanism?

retroviruses

Tumors invade other organs and tissues in a process called

metastasis

Plaque assays are used for

determine the density of phage in a culture.

Diploid cell cultures and continuous cell cultures differ in which of the following ways?

both longevity and source of cells

Viroids infect

plants

How are prions different from all other known infectious agents?

they lack nucleic acid

The viruses of fungi have RNA genomes and lack a capsid. they are therefore similar to

prions

A lipid membrane is present in which of the following?

enveloped viruses

Some human viruses are difficult to study because

they only grow in normal human cells.

Double stranded RNA genomes can be found

only in viruses

Which of the following is a feature shared by viruses and living organisms?

possession of a genome that directs synthesis of materials necessary for replication

Small circular RNA molecules without capsids are characteristic of

viroids

Viruses are shed slowly and steadily during

lysogenic infection

During _____ viruses remain dormant in animal cells.

latency

Virus replication results in the death of the cell in ______ infections.

a lytic

A ______ is a mass of neoplastic cells.

tumor

The process known as ______ is a mechanism of release for enveloped viruses.

budding

The combination of a virus's protein coat and nucleic acid core is called the (capsid/ virion/ nucleocapsid).

nucleocapsid

Viral capsids are composed of subunits called (nucleocapsids/ capsomeres).

capsomeres

Virus infection is initiated by the specific (fit/affinity/interaction) between proteins on the surface of a virion the surface of the target cell.

affinity

Some viruses can be cultured on (continuous/diploid/animal) cells which are descended from neoplastic cells.

continuous

The virions shown in the figure have a (polyhedral/ helical/ complex) capsid.

complex

Another term for a lysogenic phage is a (temperate/ latent/ prophage) phage.

temperate

The process in which viral capsids are removed within the infected cell is called (entry/ disassembly/ uncoating).

uncoating

Uncontrolled cell division in animals is known as (metastasis/ neoplasia/ cancer).

neoplasia

RNA viruses such as HIV require the activity of reverse (transcriptase/ polymerase) to become proviruses.

transcriptase

In enveloped viruses, virus-encoded (matrix/ capsomers/ envelope) proteins are required for the assembly of the envelope around the capsid.

matrix

Genes that play a role in proper cell division but may also play a role in some types of cancer are called (oncogenes/ protooncogenes/ promoters)

protooncogenes

A (colony/ plaque) is a clear zone on a bacterial lawn where cells have been killed by the activity of a bacteriophage.

plaque

Three (orders/ families/ classes) represent the highest level of taxonomic rank uses in classifying viruses.

orders

Prions are composed of a single protein called (plaque/BSE/ PrP).

PrP

An animal virus that does not have an envelope is described as a (naked/ unenveloped/ capsid) virion.

naked