Microbiology Chapter 6
Which of the following best defines a plaque-forming unit (PFU)? Multiple choice question. Number of cells killed (or lysed) by a virus. The number of plaques counted in a single lawn of cells. A number of virions that generates a single plaque The number of viruses needed to kill one cell.
A number of virions that generates a single plaque
Which of the following best defines a plaque-forming unit (PFU)? Multiple choice question. The number of plaques counted in a single lawn of cells. Number of cells killed (or lysed) by a virus. A number of virions that generates a single plaque The number of viruses needed to kill one cell.
A number of virions that generates a single plaque
Which of the following best describes a virus? Multiple choice question. A pathogen that can infect a host cell but can also replicate independently. An acellular infectious agent that can only replicate within a host cell. A group of acellular agents that only infect human cells. A cellular infectious agent that can replicate only replicate within a host cell.
An acellular infectious agent that can only replicate within a host cell.
Which of the following viral structures is composed of just the protein that surrounds the nucleic acid? Multiple choice question. Protomer Nucleocapsid Capsid Viral envelope
Capsid
Virus (e) in this image has a capsid with which sort of viral symmetry? Multiple choice question. Helical Pleomorphic Complex Icosahedral
Complex
Which type of genome would seem simplest to replicate in a host cell? Multiple choice question. DNA RNA
DNA
Which type of genome would seem simplest to replicate in a host cell? Multiple choice question. RNA DNA
DNA
Which two of the following statements regarding the packaging of DNA into the T4 phage head are false? Multiple select question. DNA is incorporated into the head by a complex of proteins called the viroplasm. The packasome proteins catalyze the fusion of the head and tail assembly. Energy required to pack DNA into the phage head is supplied in the form of ATP. The enzyme terminase moves DNA into the head.
DNA is incorporated into the head by a complex of proteins called the viroplasm. The packasome proteins catalyze the fusion of the head and tail assembly.
Which of the following viral structures comes principally from the host cell? Multiple choice question. Nucleic acids Tail fibers Capsid Envelope
Envelope
Select the four cellular structures that can be the source of viral envelopes. Multiple select question. mitochondria Golgi apparatus plasma membrane ribosome nuclear membrane endoplasmic reticulum
Golgi apparatus plasma membrane nuclear membrane endoplasmic reticulum
Which two of the following have direct involvement with viral attachment? Multiple select question. Host receptor Host mitochondrion Viral nucleic acid Viral ligand
Host receptor Viral ligand
What name is given to a viral capsid that is composed of 20 equilateral triangular protomer faces? Multiple choice question. Complex Icosahedral Helical Pleomorphic
Icosahedral
Question Mode Multiple Choice Question Because their host cells typically lack the appropriate enzymes, which type of viruses always encode the enzymes needed to copy their genome? Multiple choice question. RNA viruses bacteriophage archaeal viruses DNA viruses
RNA viruses
Once a virus enters the cytoplasm of a host cell, which step would occur next? Multiple choice question. Host cell lysis Synthesis of ATP Replication of the viral genome Virion assembly
Replication of the viral genome
Which of the following viral structures is principally involved in attaching to host cells? Multiple choice question. The viral envelope Spike proteins Viral nucleic acids Phospholipids
Spike proteins
What viral life cycle step generally occurs after the virus has uncoated? Multiple choice question. Entry Self-assembly Synthesis Attachment
Synthesis
Select the two main advantages that explain why lysogeny evolved in bacteriophages. Multiple select question. The bacteriophage can survive at a high multiplicity of infection. It allows the phage to quickly kill its host and move on. Viral nucleic acid can be maintained in a dormant host. The bacteriophage can survive at a low multiplicity of infection.
The bacteriophage can survive at a high multiplicity of infection. Viral nucleic acid can be maintained in a dormant host.
Select all that apply Which two of the following statements regarding the packaging of DNA into the T4 phage head are false? Multiple select question. Energy required to pack DNA into the phage head is supplied in the form of ATP. The enzyme terminase moves DNA into the head. The packasome proteins catalyze the fusion of the head and tail assembly. DNA is incorporated into the head by a complex of proteins called the viroplasm.
The packasome proteins catalyze the fusion of the head and tail assembly. DNA is incorporated into the head by a complex of proteins called the viroplasm.
Which is NOT true about lysogenic bacteria? Multiple choice question. They would normally stop dividing. They can reproduce normally. When they reproduce, they also copy the viral DNA. They could become pathogenic.
They would normally stop dividing.
True or false: Viruses that have RNA genomes must carry enzymes in their virion to aid in replication once in a host cell. True false question. True False
True
Viral specificity for a host cell type is dependent on ____. Multiple select question. Viral ligand Viral nucleic acid Host receptor Host metabolism
Viral ligand Host receptor
Select the two main advantages that explain why lysogeny evolved in bacteriophages. Multiple select question. It allows the phage to quickly kill its host and move on. Viral nucleic acid can be maintained in a dormant host. The bacteriophage can survive at a low multiplicity of infection. The bacteriophage can survive at a high multiplicity of infection.
Viral nucleic acid can be maintained in a dormant host. The bacteriophage can survive at a high multiplicity of infection.
Middle proteins in a viral life cycle function to Multiple select question. activate expression of late genes replicate the viral genome form the capsid take over the host cell lyse the host cell
activate expression of late genes replicate the viral genome
Middle proteins in a viral life cycle function to Multiple select question. lyse the host cell form the capsid activate expression of late genes take over the host cell replicate the viral genome
activate expression of late genes replicate the viral genome
Neuraminidase is an enzyme found in the spikes of influenza virus that ____. Multiple choice question. binds and clumps red blood cells triggers apoptosis allows attachment of the virus to neuron cells allows mature virions to leave infected cells
allows mature virions to leave infected cells
The function of viral spike proteins is to ____. Multiple choice question. promote viral genome replication attach to a host cell surface puncture host cell membranes aid in capsid assembly
attach to a host cell surface
The first step in a typical viral life cycle is ________________. Listen to the complete question
attachment
The first step in the viral life cycle is ____. Multiple choice question. synthesis attachment release assembly
attachment
When performing a viral plaque-forming assay and using the terminology "bacterial lawn", the word "lawn" refers to Multiple choice question. bacterial cells on a lawn of nutrients (it refers to the media). bacterial cells virtually side-by-side, covering an agar plate. enough viruses to kill all the bacteria. bacterial colonies scattered uniformly across the agar plate.
bacterial cells virtually side-by-side, covering an agar plate.
When performing a viral plaque-forming assay and using the terminology "bacterial lawn", the word "lawn" refers to Multiple choice question. bacterial cells virtually side-by-side, covering an agar plate. bacterial colonies scattered uniformly across the agar plate. bacterial cells on a lawn of nutrients (it refers to the media). enough viruses to kill all the bacteria.
bacterial cells virtually side-by-side, covering an agar plate.
The specific term used to describe viruses that infect bacterial cells is ______. Multiple choice question. lysogen satellite bacteriophage prophage
bacteriophage
Viruses that infect bacterial cells are called ____________.
bacteriophages
Hemagglutinin is a protein found in the spikes of influenza virus that ______. Multiple choice question. triggers apoptosis allows mature virions to leave infected cells binds and clumps red blood cells allows attachment to neurons
binds and clumps red blood cells
Viruses exist _____ cells. Multiple choice question. only inside infected both outside and inside only outside
both outside and inside
The protein coat that surrounds the viral nucleic acid is called the_____________________ .
capsid
Many RNA viruses must ______ to replicate their genomes. Multiple choice question. modify host enzymes use host enzymes hijack the host nucleus carry their own enzymes
carry their own enzymes
Many RNA viruses must ______ to replicate their genomes. Multiple choice question. use host enzymes carry their own enzymes hijack the host nucleus modify host enzymes
carry their own enzymes
Viral symmetry that is both icosahedral and helical and possibly other symmetry is collectively referred to as ____ symmetry. Multiple choice question. radial geometric complex pleomorphic
complex
In contrast to viral genomic DNA, which may be dsDNA, ssDNA, dsRNA, or ssRNA, cellular genomes are always _____ Multiple choice question. ssDNA dsRNA ssRNA dsDNA
dsDNA
Which of the following genomes could be included within a single virus? Multiple select question. dsRNA ssRNA ssDNA dsDNA both ssDNA and ssRNA both RNA and DNA both dsRNA and dsDNA
dsRNA ssRNA ssDNA dsDNA
Viruses with a lipid membrane are often called ____. Multiple choice question. enveloped virions phage naked
enveloped
True or false: The cell membrane is the only host cell structure from which enveloped viruses obtain their envelope. True false question. True False
false
True or false: The cell membrane is the only host cell structure from which enveloped viruses obtain their envelope. True false question.TrueFalse
false
Late proteins in a viral life cycle function to Multiple select question. form the capsid activate expression of late genes replicate the viral genome take over the host cell lyse the host cell
form the capsid lyse the host cell
Late proteins in a viral life cycle function to Multiple select question. form the capsid lyse the host cell activate expression of late genes take over the host cell replicate the viral genome
form the capsid lyse the host cell
Viral spike proteins on the influenza virus that facilitate viral attachment to red blood cells are called _____. Multiple choice question. collagenase hemagglutinin pepsin neuraminidase
hemagglutinin
The energy for viral replication, gene expression, and nucleocapsid assembly comes from _____. Multiple choice question. host ATP the proton motive force breakdown of the viral capsid viral ATP
host ATP
RNA viruses always encode the enzymes needed to replicate their genomes because Multiple choice question. host cells do not have the RNA nucleotide building blocks to make RNA-based viruses. otherwise host cells will not allow RNA viruses to enter cells. host cells typically do not have ways to make RNA from RNA templates.
host cells typically do not have ways to make RNA from RNA templates.
What name is given to the process that leads a lysogenic virus to transition to the lytic cycle? Multiple choice question. induction initiation lysogenic conversion transduction
induction
What name is given to the process that leads a lysogenic virus to transition to the lytic cycle? Multiple choice question. lysogenic conversion transduction initiation induction
induction
When a change in conditions causes a prophage to begin synthesizing and assembling new virions, this is called __________________.
induction
When a change in conditions causes a prophage to begin synthesizing and assembling new virions, this is called ______________________. Listen to the complete question
induction
Because they can inhibit infection of the same cell by more than one virion, temperate bacteriophages have an advantage at a high MOI, which stands for multiplicity of _______________.
infection
Because they can inhibit infection of the same cell by more than one virion, temperate bacteriophages have an advantage at a high MOI, which stands for multiplicity of ________________.
infection
Because they can inhibit infection of the same cell by more than one virion, temperate bacteriophages have an advantage at a high MOI, which stands for multiplicity of _____________________.
infection
Select all that apply Select the three methods used by viruses to gain entry into host cells. Multiple select question. injection of viral nucleic acid into the cell endocytosis of the virus into the cell fusion of the viral envelope with host cell membrane fusion of the viral capsid with the host cell lysosomes entry of the viral envelope only, leaving the capsid outside the cell
injection of viral nucleic acid into the cell endocytosis of the virus into the cell fusion of the viral envelope with host cell membrane
An icosahedral capsid _____. Multiple choice question. is a regular polyhedron is usually found on viroids can only enclose small RNA genomes requires the presence of a membrane envelope
is a regular polyhedron
A bacterial plaque assay requires the use of a ____. Multiple choice question. red blood cells blood agar plates lawn of cells high titer of viruses
lawn of cells
Select the two most common forms of viral release. Multiple select question. fusion phagocytosis endocytosis budding lysis
lysis budding
Most viruses will leave a host cell by bursting the cell, a process called ____________, or by pushing through the cell membrane while taking some of that membrane with it, a process called ________________.
lysis, budding
Bacteria infected by temperate phages are called ______ bacteria. Multiple choice question. heat-shocked lytic lysogenic transfected
lysogenic
Some temperate phage can change the phenotype of a host bacterial cell and this is called ____. Multiple choice question. phenotype conversion lysogenic conversion transfection cytopathic effect
lysogenic conversion
______________ __________________ is when a temperate phage causes a change to the phenotype of an infected bacterial cell.
lysogenic conversion
Viruses that lack a viral envelope are often called ____. Multiple choice question. virions protomers naked phage
naked
Viral spike proteins on the influenza virus that aid in the release of mature virions from the host cell are composed of the enzyme _____. Multiple choice question. pepsin collagenase hemagglutinin neuraminidase
neuraminidase
Select the four cellular structures that can be the source of viral envelopes. Multiple select question. mitochondria nuclear membrane plasma membrane Golgi apparatus endoplasmic reticulum ribosome
nuclear membrane plasma membrane Golgi apparatus endoplasmic reticulum
The simplest viruses consist of nucleic acid surrounded by a protein coat. This composite structure of viral nucleic acid and protein is called a ______. Multiple choice question. capsid nucleocapsid protomer viroid
nucleocapsid
The simplest viruses consist of nucleic acid surrounded by a protein coat. This composite structure of viral nucleic acid and protein is called a ______. Multiple choice question. nucleocapsid protomer viroid capsid
nucleocapsid
The main difference between virulent phage and temperate phage is that virulent phage _____. Multiple choice question. always cause disease only have a lytic cycle always integrate into the host genome alternate between temperate and virulent
only have a lytic cycle
DNA is incorporated into the T4 phage head by proteins called the _____. Multiple choice question. terminase complex packasome viral replication complex viroplasm
packasome
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 ________________ assay.
plaque forming
One method of counting temperate viruses involves mixing the virus and susceptible cells on top of a solid medium. As each virus begins lysing more and more cells, holes can be visualized on top of the medium. The virus-induced holes are specifically called ____________.
plaques
One method of counting temperate viruses involves mixing the virus and susceptible cells on top of a solid medium. As each virus begins lysing more and more cells, holes can be visualized on top of the medium. The virus-induced holes are specifically called ______________________.
plaques
Which two of the following components make up a viral nucleocapsid? Multiple select question. peptidoglycan protein coat cell wall envelope nucleic acid
protein coat nucleic acid
Which two of the following components make up a viral nucleocapsid? Multiple select question. peptidoglycan protein coat nucleic acid envelope cell wall
protein coat nucleic acid
The last step in the replication cycle of a virus is generally called ____________. Listen to the complete question
release
Which stage of virus replication is shown in the image? Multiple choice question. synthesis penetration release uncoating
release
Which of the following genomes could be included within a single virus? Multiple select question. ssRNA dsDNA ssDNA both RNA and DNA dsRNA both dsRNA and dsDNA both ssDNA and ssRNA
ssRNA dsDNA ssDNA dsRNA
Which of the following describe a bacteriophage that may lyse its host cell, or remain within the cell without lysing it? Multiple choice question. prophage virulent pleomorphic temperate
temperate
Enveloped viruses gain their envelope from ____. Multiple choice question. the environment the host cell membrane biosynthesis and secretion water absorbed into the capsid
the host cell membrane
Which of the following best describes viral tropism? Multiple choice question. the specific infection of host cells involved in digestion the specific location in the body where a virus can infect the specific cell type that a virus can infect Infection of nasopharynx cells
the specific cell type that a virus can infect
Some viruses infect specific tissue types but not others. This is called ____. Multiple choice question. fusion transduction specificity tropism
tropism
Some viruses infect specific tissue types but not others. This is called ____. Multiple choice question. transduction fusion specificity tropism
tropism
The results of virus titration using a plaque-forming assay are normally expressed in PFUs, or plaque-forming _________________.
units
The results of virus titration using a plaque-forming assay are normally expressed in PFUs, or plaque-forming __________________.
units
A complete virus particle is called a(n) ___________.
virion
A complete virus particle is called a(n) _____________.
virion
A complete virus particle is referred to as a ____. Multiple choice question. bacteriophage virus virion viroid
virion
An acellular infectious agent that must replicate within a host cell is a(n) ______________.
virus
In the context of virus replication, fusion with the host cell membrane, injection of nucleic acid, and endocytosis are the three modes of _____. Multiple choice question. virus release from host cells virus assembly inside host cells synthesizing viral nucleic acids virus entry into host cells
virus entry into host cells
Viruses must replicate within a host cell because _____. Multiple choice question. the host cell provides protection viruses easily denature outside of a host cell viruses lack replication enzymes and resources
viruses lack replication enzymes and resources