microbio chapter 13
Lysogeny is best described as ______.
integration of the viral genome into the host chromosome
Infection of bacteria by ____________________phages always ends with the lysis of the host cell.
lytic, virulent
Viruses that can cause cancer in humans are known as
oncogenic viruses
Viruses that specifically target and kill cancer cells are called
oncolytic viruses
_________________ infectionscan continue with or without symptoms for years.
persistent
An infectious agent that consists of protein and no nucleic acid is called a(n)
prion
The stage of viral multiplication at which budding occurs is ______.
release
HIV is described as a _____________________because it uses reverse transcriptase to make a DNA copy from its RNA genome.
retrovirus
Which form of transduction results from excision errors during the transition from a lysogenic to lytic cycle?
specialized
__________________transduction is the result of excision errors made as temperate phages transition from a lysogenic to a lytic cycle.
specialized
A ______ phage can either cause a lytic infection or can incorporate its DNA into the host genome as a prophage.
temperate
Viral infections in plants can cause diseases ______.
that are economically devastating
In a lysogenic infection, ______.
the bacteriophage DNA integrates into the host chromosome
During viral replication, when the genome of a (+) single-stranded RNA virus is used as a template, which of the following is generated?
(-) single-stranded RNA molecules because The product is the complementary (-) single stranded RNA.
In ______-strand RNA viral genomes, the genome functions as an mRNA molecule.
+ (positive)
Replicases are ______ polymerases.
RNA-dependent RNA
The binding of a bacteriophage surface protein to a host cell receptor is called ______.
attachment
Oncoviruses are viruses that can ______.
causes cancer in humans
Which are the two major categories of viral infections?
Acute Persistent
Infectious agents that have a simpler structure than viruses include ______.
both viroids and prions
Viral genomes can be ______.
either single-stranded or double-stranded
True or false: There is no need to classify viruses because they are not living organisms.
false
In the case of animal viruses, the molecules that viral spikes attach to on the host cell in order to gain entry are typically ______.
glycoproteins
When an enveloped virus gains entry to an animal cell by fusion, the virus envelope fuses with the ______.
cytoplasmic membrane
If viruses are present in high enough concentrations in a sample, they can be quantified directly using a(n
electron
During the process that leads to a lysogenic infection, which of the following inserts the phage DNA into a bacterial chromosome?
integrase
Animal viruses can be studied by infecting ______.
live animals fertilized chicken eggs cell or tissue culture
A ______ infection results from the integration of bacteriophage DNA into the chromosome of the bacterial host.
lysogenic
Signs of viral infections in plants include ______.
presence of tumors stunted growth yellowing of leaves
A _________is an infectious agent that lacks a capsid and consists only of RNA.
viroid
The virally encoded polymerase needed for replication of RNA viruses is called a
replicase
List the steps of an animal virus infection cycle in the correct order. Start with the earliest at the top.
1. attachment 2. penetration and uncoating 3. synthesis of viral proteins and replication of the genome 4. assembly 5. release
Which form of transduction results from packaging errors during phage assembly?
generalized
In a lysogenic infection, the phage DNA that is incorporated into the bacterial host genome is called a ______.
prophage
Reverse transcriptase is a(n) ______ polymerase.
RNA-dependent DNA
Symptoms of acute viral diseases result from ______.
host tissue damage host immune response
A _______ is a single virus particle.
virion
The nucleocapsid is composed of ______.
DNA or RNA, and protein
Which of the following statements about virus nucleic acid is true?
Viruses contain either DNA or RNA.
Which of the following describes the various viral parts coming together to produce virions?
assembly
Tumors are abnormal growths that result from a malfunction in the regulation of ______.
cell growth
The replication strategies of animal viruses can be divided into three general categories:
dna viruses, rna viruses, and reverse transcribing viruses
Viruses are best described as _______.
infectious agents
Bacteriophages that can enter into a lytic cycle or a lysogenic cycle are called_____________________- phages.
temperate
A generalized infection cycle of an animal viruses can be divided into five steps:
1. attachment 2. genome entry 3. synthesis 4. assembly 5. release
_____________infections remain for years, or even the lifetime of the host, sometimes without any symptoms.
persistent
Viruses that have an RNA genome and use reverse transcriptase to synthesize a DNA copy of that genome are called ______.
retroviruses
An enzyme that uses an RNA molecule as a template to make a complementary copy of DNA is called ______.
reverse transcriptase
Which of the following are non-cellular infectious agents composed of only a single-stranded RNA molecule?
Viroids
Which of the following are non-cellular infectious agents?
Viroids Prions Viruses
Which of the following statements about viruses are true?
Viruses contain RNA or DNA but not both. The viral capsid is composed of protein.
Although live animals and fertilized chicken eggs have been used to cultivate animal viruses in the past, these have now been largely replaced by
cell/tissue culture
All of the following are required for synthesis of new virus particles in a host cell EXCEPT ______.
homologous recombination
The process by which a virus is taken up by a host cell as a result of the host cell's cytoplasmic membrane surrounding the virion to form a vesicle is called ______.
endocytosis
______________________-transduction is the result of packaging errors during the assembly stage of phage replication.
generalized
At a minimum, all viruses are composed of ______.
nucleic acids proteins
Attachment of animal viruses to the host cell typically occurs by means of ______.
spikes
When two different strains of a segmented virus enter the same cell, reassortment of the gene segments can occur, resulting in ______.
antigenic shift
During the _________________ or maturation step in viral multiplication, capsids and genetic material are packaged into virions.
assembly
Which types of viruses are released by budding?
enveloped viruses
___________________ phages cause productive infections that do not kill the host cell.
filamentous
The smallest virus is approximately 10 ______ in diameter.
nanometers
In animals, replication of most DNA viruses occurs within the host cell's
nucleus
The replication strategy of viruses can be divided into three general categories: those used by ______.
reverse transcribing viruses RNA viruses DNA viruses
Reassortment of gene segments that encode viral surface proteins recognized by the immune system can result in a loss of the immune system's ability to recognize and respond to the virus. This phenomenon is called antigenic
antigenic shift
Most animal DNA viruses replicate within the host cell's ______.
nucleus
Which of the following phage types cause productive infections that do not kill the host cell?
Filamentous
Replication of temperate phages and lytic phages have which steps in common?
Genome entry Assembly Release Attachment Biosynthesis of viral components
In a(n) ______, viral titer can be determined by counting clear zones in a monolayer of cells.
plaque assay
Bacteriophages play a fundamental role in a type of horizontal gene transfer called
transduction
Replication of temperate phages and lytic phages have which steps in common?
Assembly Attachment Release Biosynthesis of viral components Genome entry
A prion is best described as ______.
a proteinaceous infectious agent
In acute viral infections, although the infected host cells may die, the host may survive because ______.
the host's immune system may gradually eliminate the virus
A capsid is ______.
the protein coat that surrounds the viral genome
Human cells are larger than viruses by which size factor?
thousand
The replication strategy of viruses can be divided into three general categories: those used by ______.
DNA viruses RNA viruses reverse transcribing viruses
Which of the following describe a type of relationship that bacteriophages can have with their host?
Latent infection where host cell genotype is changed Productive lytic infection
What term is used to describe the transfer of genetic information from one bacterium to another bacterium by a bacteriophage?
transduction
An abnormal growth of tissue resulting from a malfunction in the normally highly regulated process of cell growth is a
tumor
A complete viral particle, which typically consists of nucleic acid surrounded by a protein coat, is called a(n
virion
A ____________________is an infectious agent that lacks a capsid and consists only of RNA.
viroid
Bacteriophages that exit the host cell at the end of an infection by lysing it are called _______ phages.
virulent
The viral genome is protected from the environment by a protein shell called the ______.
capsid
The study of bacteriophages has advanced much faster than investigations on animal viruses in part because ______.
it is easier to grow bacterial cells than animal cells
Which of the following processes are required for production of virus particles in a host cell?
Replication of viral genome Translation of viral genes Transcription of viral genes
The major categories of animal viral infections are
acute infections, characterized by the sudden onset of symptoms of a relatively short duration
Mutations in the influenza virus genome can result in minor changes in key viral surface proteins. This type of variation is called antigenic
antigenic drift
The accumulation of mutations in genes that encode viral surface proteins recognized by the immune system results in a type of antigenic variation called ______.
antigenic drift
