Micro Bio Chp 13 Exam 2
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.
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?
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?
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?
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?
Which of the following is matched Incorrectly?
adenovirus; membrane fusion
Reverse transcriptase is associated with which of the following?
The genome of which of the following types of animal virus can act directly as mRNA?
Which of the following types of animal virus requires RNA-dependent RNA transcriptase to be replicated?
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?
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?
Tumors invade other organs and tissues in a process called
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
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
A lipid membrane is present in which of the following?
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
Viruses are shed slowly and steadily during
During _____ viruses remain dormant in animal cells.
Virus replication results in the death of the cell in ______ infections.
A ______ is a mass of neoplastic cells.
The process known as ______ is a mechanism of release for enveloped viruses.
The combination of a virus's protein coat and nucleic acid core is called the (capsid/ virion/ nucleocapsid).
Viral capsids are composed of subunits called (nucleocapsids/ 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.
Some viruses can be cultured on (continuous/diploid/animal) cells which are descended from neoplastic cells.
The virions shown in the figure have a (polyhedral/ helical/ complex) capsid.
Another term for a lysogenic phage is a (temperate/ latent/ prophage) phage.
The process in which viral capsids are removed within the infected cell is called (entry/ disassembly/ uncoating).
Uncontrolled cell division in animals is known as (metastasis/ neoplasia/ cancer).
RNA viruses such as HIV require the activity of reverse (transcriptase/ polymerase) to become proviruses.
In enveloped viruses, virus-encoded (matrix/ capsomers/ envelope) proteins are required for the assembly of the envelope around the capsid.
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)
A (colony/ plaque) is a clear zone on a bacterial lawn where cells have been killed by the activity of a bacteriophage.
Three (orders/ families/ classes) represent the highest level of taxonomic rank uses in classifying viruses.
Prions are composed of a single protein called (plaque/BSE/ PrP).
An animal virus that does not have an envelope is described as a (naked/ unenveloped/ capsid) virion.