Micro Exam 3 Chapter 13

A lipid membrane is present in which of the following? A) naked viruses B) enveloped viruses C) prions D) viroids E) both prions and viroids

B) enveloped viruses

Which of the following types of animal virus requires RNA-dependent RNA transcriptase to be replicated?A) +ssRNA viruses B) ssDNA viruses C) -ssRNA viruses D) retroviruses E) dsDNA viruses

C) -ssRNA viruses

Which of the following statements regarding virus taxonomy is true? A) Viruses are classified on the basis of the taxonomy of their host organisms. B) Virus classes are well established. C) Some virus family names are derived from the name of an important member of the family. D) The species epithet is a Latin descriptor of the virion structure. E) Virus classes are based on the domain of the host organism.

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

Which of the following events occurs in the lytic cycle of bacteriophage T4 infection but NOT in the lysogenic cycle? A) attachment B) entry C) digestion of host DNA D) viral protein synthesis E) both digestion of host DNA and viral proteins synthesis

C) digestion of host DNA

Which of the following is primarily responsible for the shape of a virion? A) the type of nucleic acid B) the number of segments of the viral genome C) the source of the envelope D) the capsid E) the specific host protein the virus targets

D) the capsid

Which of the following infectious particles do NOT have protein in their structure? A) bacteriophages B) prions C) animal viruses D) viroids E) both prions and viroids

D) viroids

Prions are composed of a single protein called ______.

PrP

Viruses with -ssRNA require the activity of __________ for their replication.

RNA-dependent RNA polymerase

T/F Bovine spongiform encephalopathy is an example of a prion disease.

TRUE

T/F Budding release of virus may result in long lasting or persistent infection.

TRUE

T/F Fertilized chicken eggs are used to culture some vaccine strains.

TRUE

T/F Members of a virus family have the same type of nucleic acid.

TRUE

T/F Most viruses cannot be seen by light microscopy.

TRUE

T/F Protozoa are susceptible to viral attack.

TRUE

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

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

Why is lysogeny advantageous to a bacteriophage?

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

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

They have no extracellular state.

How are prions different from all other known infectious agents?

They lack nucleic acid

In what ways do viruses differ from other pathogens?

Viruses lack cytoplasm and organelles.

Virus replication results in the death of the cell in ________ infection(s).

a lytic

Host specificity of a virus is due to

interactions between viral and cellular surface molecules.

During ________, viruses remain dormant in animal cells.

latency

Naked capsid animal viruses are commonly released from the infected cell by ________, a process the host cell does not survive.

lysis

Tumors invade other organs and tissues in a process called

metastasis

An animal virus that does not have an envelope is described as a(n) ____________ virion.

naked

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

neoplasia

Uncontrolled cell division in animals is known as ____________.

neoplasia

Continuous cell cultures are developed from _______ cells.

neoplastic

The combination of a virus's protein coat and nucleic acid core is called the _________

nucleocapsid

Genes that play a role in proper cell division but may also play a role in some types of cancer are called ________.

protooncogenes

Disadvantages of continuous cell cultures include

they may be significantly different genetically from the original source animal.

RNA viruses such as HIV require the activity of reverse _________ to become proviruses

transcriptase

A ________ is a mass of neoplastic cells.

tumor

The process in which viral capsids are removed within the infected cell is called __________

uncoating

40) Small circular RNAs called ________ are plant pathogens.

viroids

What is a virion?

A single virus particle outside a cell.

Which of the following lists stages of a lytic replication cycle in order, from earliest to latest stages? I. Synthesis II. Assembly III. Attachment IV. Release V. Entry A) III, V, I, II, IV B) III, II, V, I, IV C) V, III, II, IV, I D) I, III, V, II, IV E) I, II, III, V, IV

A) III, V, I, II, IV

Which of the following is a feature shared by viruses and living organisms? A) possession of a genome that directs synthesis of materials necessary for replication B) presence of cytoplasm C) metabolic capability D) responsiveness E) the ability to increase in size

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

Which of the following is a characteristic by which viruses are classified? A) type of nucleic acid B) type of life cycle C) number of chromosomes D) type of host E) size

A) type of nucleic acid

Plaque assays are used for

determining the density of phage in a culture.

Replication of most ________ viruses is similar to normal cellular processes.

dsDNA

Attachment of herpesviruses results in ________, a process in which the host cell facilitates viral entry.

endocytosis

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

entry and release

The ________ of a virion determines the type of cell it enters.

glycoproteins

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

+ssRNA viruses

T/F Enveloped animal viruses enter cells in a process similar to the bacteriophage infection process.

FALSE

T/F Viruses cause most human cancers.

FALSE

Which of the following taxa are used for classification of viruses as well as organisms? A) Kingdom B) Class C) Division D) Family E) Division, Class, and Family are used in both taxonomic schemes.

D) Family

Which of the following is CORRECT regarding the viral envelope? A) It contains only viral proteins. B) It contains only host cell proteins. C) It is composed of sterols. D) It is composed of cellular phospholipid membrane, cellular and viral proteins. E) It is composed of sterols of viral proteins only.

D) It is composed of cellular phospholipid membrane, cellular and viral proteins.

Which of the following agents is capable of inducing conversion of a prophage to the lytic cycle? A) UV light B) X rays C) presence of +ssRNA D) both UV light and X rays E) both UV light and the presence of +ssRNA

D) both UV light and X rays

Which of the following laboratory procedures is used for culturing animal viruses in the laboratory? A) cell cultures B) broth cultures C) embryonated eggs D) both cell cultures and embryonated eggs E) synthetic cytoplasm

D) 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? A) +ssRNA viruses B) dsRNA viruses C) -ssRNA viruses D) retroviruses E) both +ssRNA and -ssRNA viruses

D) retroviruses

Reverse transcriptase is associated with which of the following? A) dsDNA viruses B) +ssRNA viruses C) -ssRNA viruses D) retroviruses E) dsRNA viruses

D) retroviruses

Which of the following is associated with the attachment of a bacteriophage to a bacterial cell? A) random collisions B) chemical attractions C) receptor specificity D) both chemical attractions and receptor specificity E) random collisions, chemical attractions, and receptor specificity

E) random collisions, chemical attractions, and receptor specificity

Which of the following membranes can give rise to a viral envelope? A) the nuclear membrane B) the cytoplasmic membrane C) the endoplasmic reticulum D) the nuclear and cytoplasmic membranes E) the nuclear and cytoplasmic membranes and the endoplasmic reticulum

E) the nuclear and cytoplasmic membranes and the endoplasmic reticulum

T/F All viruses use the host cell's nucleic acid polymerases for replication.

FALSE

T/F Bacteriophage release is a gradual process in which small numbers are released at a time.

FALSE

A(n) ________ is a virus that infects bacterial cells.

bacteriophage

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

both protection and recognition

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

budding

Viral capsids are composed of subunits called __________.

capsomeres

The virions shown in Figure 13.1 have a ______________ capsid.

couples

Double-stranded RNA genomes can be found

only in viruses

Seven __________ represent the highest level of taxonomic rank used in classifying viruses

orders

Viroids infect

plants

A __________ is a clear zone on a bacterial lawn where cells have been killed by the activity of a bacteriophage.

plaque

A(n) ________ is a bacterial virus which is integrated into the host cell DNA.

prophage

Some viruses have a dsDNA genome. Others may have a ________ genome.

ssDNA, ssRNA, or dsRNA

The stage of virus infection called ________ is the stage most dependent on host cell proteins.

synthesis

Another term for a lysogenic phage is a _______________ phage.

temperate