MIC 102 unit 4-6
Which of the following best defines a plaque-forming unit (PFU)?
A number of virions that generates a single plaque
Which of the following best defines a virulent phage?
A virus that always progresses to lysis of the infected cell
Which of the following best defines a temperate phage?
A virus that can integrate its genome into the host genome.
The first step in a typical viral life cycle is
Blank 1: attachment or adsorption
The specific process of an enveloped virus leaving the cell is called
Blank 1: budding
Virally infected eukaryotic cells often show microscopic or macroscopic abnormalities that are generally called
Blank 1: cytopathic
The dose of virions needed to infect 50% of host organisms is called the
Blank 1: infectious or id50
The dose of virions needed to kill 50% of host organisms is called the
Blank 1: lethal, ld50, or lethal dose
When a temperate phage integrates its genome into a host genome, the relationship between the phage and the host is termed
Blank 1: lysogeny, lysogenic cycle, or lysogenic
Viruses can be quantified using a lawn of cells and counting the number of "clear spots" where the cells were killed by viruses. This sort of assay is called a
Blank 1: plaque or plaque forming
A host cell that contains a ------ the nucleic acid of a temperate phage, can divide many times.
Blank 1: prophage
The last step in the replication cycle of a virus is generally called
Blank 1: release, shedding, or virion release
Bacteriophages that can integrate their genome into the host genome are called
Blank 1: temperate, lysogenic, temperates, or lysogenics
The results of virus titration using a plaque-forming assay are normally expressed in PFUs, or plaque-forming
Blank 1: units
An infectious agent composed of only RNA is called a(n)
Blank 1: viroid
Bacteriophages that always proceed to lyse the infected cell are called ----- phage
Blank 1: virulent or lytic
A tumor is a growth or lump of tissue resulting from
Neoplasia
Which of the following describes a tumor resulting from unregulated abnormal new cell growth and reproduction of a similar cell type?
Neoplasia
Viroids are infectious agents that consist of _____.
RNA only
What viral life cycle step generally occurs after the virus has uncoated?
Synthesis
Which of the following best defines what "infectious dose (ID50)" means?
The dilution that contains enough virions to infect 50% of the host organisms
Which of the following best defines what "lethal dose (LD50)" means?
The dilution that contains enough virions to kill 50% of the host organisms
Which two of the following viral activities occurs during "viral entry"?
Uncoating Penetration
Which of the following is the study of viruses?
Virology
The best definition of cytopathic effects caused by a viral infection of eukaryotic cells is
changes or abnormalities in infected cells that are distinct from lysis
In contrast to viral genomic DNA, which may be dsDNA, ssDNA, dsRNA, or ssRNA, cellular genomes are always _____
dsDNA
Which of the following genomes could be included within a single virus?
dsRNA dsDNA ssRNA ssDNA
The second step of the viral life cycle is ____.
entry
The outer lipid membranous layer found surrounding some viruses is called the
envelope
The energy for viral replication, gene expression, and nucleocapsid assembly comes from _____.
host ATP
Budding is best described as
how enveloped viruses acquire their membranes
An icosahedral capsid _____.
is a regular polyhedron
A helical capsid _____.
is shaped like a hollow tube with protein walls
A bacterial plaque assay requires the use of a ____.
lawn of cells
A viral envelope is composed of primarily ____.
lipids
The relationship between a temperate phage and the host cell is called ____.
lysogeny
The simplest viruses consist of nucleic acid surrounded by a protein coat. This composite structure of viral nucleic acid and protein is called a ______.
nucleocapsid
The main difference between virulent phage and temperate phage is that virulent phage _____.
only have a lytic cycle
Infectious agents composed entirely of protein are called _____.
prions
The nucleic acid of a temperate phage that is either integrated into the host cell's genome, or remains free in the cytoplasm, is called a _____.
prophage
Which two of the following components make up a viral nucleocapsid?
protein coat nucleic acid
Prions are composed of _____.
protein only
What term describes the host cell component that a virus will bind for attachment?
receptor
jakahko
receptor
Which stage of virus replication is shown in the image?
release
Which two stages of viral replication occur after viral synthesis?
release assembly
Once a virus enters the cytoplasm of a host cell, it begins to _____.
replicate its genome
The viral-encoded proteins that project from a viral envelope surface are called ____.
spike proteins
Which of the following describe a bacteriophage that may lyse its host cell, or remain within the cell without lysing it?
temperate
Enveloped viruses gain their envelope from ____.the host cell membrane
the host cell membrane
Virus (e) in this image has a capsid with which sort of viral symmetry?
Complex
Which type of genome would seem simplest to replicate in a host cell?
DNA
Which of the following viral structures comes principally from the host cell?
Envelope
What name is given to a viral capsid that is shaped like a hollow tube with protein walls?
Helical
What name is given to a viral capsid that is composed of 20 equilateral triangular protomer faces?
Icosahedral
This image depicts which stage of T4 bacteriophage replication?
assembly
The first step in the viral life cycle is ____.
attachment
Viral symmetry that is both icosahedral and helical and possibly other symmetry is collectively referred to as ____ symmetry.
binal
Spikes, or peplomers, are _____.
virally-encoded proteins that project from the envelope surface
A complete virus particle is referred to as a ____.
virion
