MIBO 3500 Exam 3 Study Guide (UGA) UPDATED ACTUAL Questions And
Correct Answers
C
Terms in this set (84)
6.a Contrast the differences between the three forms of A virion is a virus particle that is inert and consists of a nucleic acid enclosed by a
virus: virion, intracellular replication complex, and viral protein capsid --> some can package enzymes and possess lipid envelopes
genome integrated in host DNA. *Virions do NOT carry out any metabolism or energy conversion*
The intracellular replication complex is located within a host cell and the viral
gene products direct the cell's enzymes to assemble progeny virions at "virus
factories" (replication complexes)
*Requires host ribosomes and collaboration between host & viral proteins*
Viral genome integrated within host DNA --> some viral genomes can integrate
within a host chromosome and replicate as a part of the host
*Integration can be permanent, and the viral genome may also be reactivated to
start assembling virions*
6.b Draw and label examples of the different virus
structures including the location of the viral genome,
capsid shape, and important accessory components (like
tail fibers, tail sheath and tube): symmetrical-helical
6.b Draw and label examples of the different virus
structures including the location of the viral genome,
capsid shape, and important accessory components (like
tail fibers, tail sheath and tube): symmetrical- icosahedral
6.b Draw and label examples of the different virus
structures including the location of the viral genome,
capsid shape, and important accessory components (like
tail fibers, tail sheath and tube): tailed bacteriophage
6.b Draw and label examples of the different virus
structures including the location of the viral genome,
capsid shape, and important accessory components (like
tail fibers, tail sheath and tube): asymmetrical
6.b Draw and label examples of the different virus
structures including the location of the viral genome,
capsid shape, and important accessory components (like
tail fibers, tail sheath and tube): enveloped
,6.c Describe the process for cell entry for enveloped Enveloped viruses fuse envelopes w/ the host cell or endosome membrane and
viruses, filamentous phages, and tailed phages. release the virion into the cell. They use glycoprotein spike proteins to attach to
the host cell, while the phage capsid remains outside and attached to the cell
surface.
Filamentous phages use short tail fibers that mediate specific attachment to the
host; specifically attaches to the F pilus of E. coli.
Tailed phages have proteins in the tail that bind to a specific receptor on the
surface of the bacterial cell. The phage stabilizes itself by using its baseplate and
then injects its dsDNA genome into the cytoplasm of the bacterium.
6.e Describe the ways a bacterial cell can defend itself Genetic resistance --> bacteria acquire random mutations in their genomes as
against bacteriophage infection. they reproduce and when they are attacked by bacteriophages, populations
undergo natural selection so mutants that are harder to infect will survive. They
can resist by expressing a gene that encodes an altered host receptor protein that
fails to bind the viral coat protein, so a different cellular protein evolves to block
phage invasion.
Restriction endonucleases --> bacteria modify their DNA by adding methyl
groups to bases within certain sequences. Bacteria then express restriction
endonucleases which are enzymes that cleave DNA lacking the methylated
patterns.
CRISPR --> bacteria have an adaptive defense against viruses that involves short
DNA sequences homologous to DNA phages that could infect the cell. When a
phage attacks a bacterium and bacterial enzymes succeed in destroying the
phage DNA, they can copy a tiny piece of it as a CRISPR segment so the host cell
remembers infection by the specific phage. The next time the adapted host cell is
attacked by the same phage, all of the genomic CRISPR sequences are expressed
as RNA.
6.f Define the Baltimore Classification System The Baltimore Classification System is based on the premise that the primary
(understand the basis for the classification which includes distinction among classes of viruses is that the genome composition (RNA or
genome composition, route to express mRNA, method of DNA) and the route used to express mRNA differ
genome replication). *Different genomes use different mechanisms to produce mRNA and this has
generated distinct groups of viruses w/ shared ancestry*
6.f Understand the basic replication cycles of the Group I: double-stranded DNA viruses--> uses its own or host DNA polymerases
examples discussed in class from four Baltimore for replication
classification groups: Papilloma virus (dsDNA)
Example: Papilloma virus
HPV has a dormant provirus cycle and an active replication cycle.
1. Host DNA-dependent RNA polymerase transcribes the viral genes
2. The mRNA is translated in the ER
3. Host DNA polymerase replicates the genome
4. Virions are assembled and released
The provirus can cause cells to become cancer cells (transformed). It is the
primary cause of cervical cancer, can cause throat and anal cancer in men and
women, and penile cancer in men
, 6.f Understand the basic replication cycles of the Group IV: (+) single-stranded RNA viruses--> requires RNA-dependent RNA
examples discussed in class from four Baltimore polymerase to make a template for mRNA and genome replication
classification groups: Picornavirus (+RNA)
Example:
Picornavirus
A picornavirus inserts its (+) strand RNA through the receptor and reproduction
occurs entirely in the cytoplasm
A key step is the early translation of a viral gene to make RNA-dependent RNA
polymerase
~A -RNA strand is made from which more +RNA strands are synthesized by the
RNA-dependent RNA polymerase
~The +RNA is used as mRNA for translation of viral proteins and is packaged as the
viral genome
6.f Understand the basic replication cycles of the Group V: (-) single-stranded RNA viruses--> require RNA-dependent RNA
examples discussed in class from four Baltimore polymerase to make mRNA and replicate its genome
classification groups: Influenza virus (-RNA)
Example: Influenza virus
Influenza is enveloped (derived from cell membrane when released from the cell)
~Membrane fusion of the viral envelope with the endosome membrane releases
the RNA genome segments into the cytoplasm
Viruses must package RNA-dependent RNA polymerase with the (-) RNA genome
since it cannot be translated to produce the viral RNA polymerase
~The (-) strand is the template and the (+) strand is the sense strand (mRNA)
Correct Answers
C
Terms in this set (84)
6.a Contrast the differences between the three forms of A virion is a virus particle that is inert and consists of a nucleic acid enclosed by a
virus: virion, intracellular replication complex, and viral protein capsid --> some can package enzymes and possess lipid envelopes
genome integrated in host DNA. *Virions do NOT carry out any metabolism or energy conversion*
The intracellular replication complex is located within a host cell and the viral
gene products direct the cell's enzymes to assemble progeny virions at "virus
factories" (replication complexes)
*Requires host ribosomes and collaboration between host & viral proteins*
Viral genome integrated within host DNA --> some viral genomes can integrate
within a host chromosome and replicate as a part of the host
*Integration can be permanent, and the viral genome may also be reactivated to
start assembling virions*
6.b Draw and label examples of the different virus
structures including the location of the viral genome,
capsid shape, and important accessory components (like
tail fibers, tail sheath and tube): symmetrical-helical
6.b Draw and label examples of the different virus
structures including the location of the viral genome,
capsid shape, and important accessory components (like
tail fibers, tail sheath and tube): symmetrical- icosahedral
6.b Draw and label examples of the different virus
structures including the location of the viral genome,
capsid shape, and important accessory components (like
tail fibers, tail sheath and tube): tailed bacteriophage
6.b Draw and label examples of the different virus
structures including the location of the viral genome,
capsid shape, and important accessory components (like
tail fibers, tail sheath and tube): asymmetrical
6.b Draw and label examples of the different virus
structures including the location of the viral genome,
capsid shape, and important accessory components (like
tail fibers, tail sheath and tube): enveloped
,6.c Describe the process for cell entry for enveloped Enveloped viruses fuse envelopes w/ the host cell or endosome membrane and
viruses, filamentous phages, and tailed phages. release the virion into the cell. They use glycoprotein spike proteins to attach to
the host cell, while the phage capsid remains outside and attached to the cell
surface.
Filamentous phages use short tail fibers that mediate specific attachment to the
host; specifically attaches to the F pilus of E. coli.
Tailed phages have proteins in the tail that bind to a specific receptor on the
surface of the bacterial cell. The phage stabilizes itself by using its baseplate and
then injects its dsDNA genome into the cytoplasm of the bacterium.
6.e Describe the ways a bacterial cell can defend itself Genetic resistance --> bacteria acquire random mutations in their genomes as
against bacteriophage infection. they reproduce and when they are attacked by bacteriophages, populations
undergo natural selection so mutants that are harder to infect will survive. They
can resist by expressing a gene that encodes an altered host receptor protein that
fails to bind the viral coat protein, so a different cellular protein evolves to block
phage invasion.
Restriction endonucleases --> bacteria modify their DNA by adding methyl
groups to bases within certain sequences. Bacteria then express restriction
endonucleases which are enzymes that cleave DNA lacking the methylated
patterns.
CRISPR --> bacteria have an adaptive defense against viruses that involves short
DNA sequences homologous to DNA phages that could infect the cell. When a
phage attacks a bacterium and bacterial enzymes succeed in destroying the
phage DNA, they can copy a tiny piece of it as a CRISPR segment so the host cell
remembers infection by the specific phage. The next time the adapted host cell is
attacked by the same phage, all of the genomic CRISPR sequences are expressed
as RNA.
6.f Define the Baltimore Classification System The Baltimore Classification System is based on the premise that the primary
(understand the basis for the classification which includes distinction among classes of viruses is that the genome composition (RNA or
genome composition, route to express mRNA, method of DNA) and the route used to express mRNA differ
genome replication). *Different genomes use different mechanisms to produce mRNA and this has
generated distinct groups of viruses w/ shared ancestry*
6.f Understand the basic replication cycles of the Group I: double-stranded DNA viruses--> uses its own or host DNA polymerases
examples discussed in class from four Baltimore for replication
classification groups: Papilloma virus (dsDNA)
Example: Papilloma virus
HPV has a dormant provirus cycle and an active replication cycle.
1. Host DNA-dependent RNA polymerase transcribes the viral genes
2. The mRNA is translated in the ER
3. Host DNA polymerase replicates the genome
4. Virions are assembled and released
The provirus can cause cells to become cancer cells (transformed). It is the
primary cause of cervical cancer, can cause throat and anal cancer in men and
women, and penile cancer in men
, 6.f Understand the basic replication cycles of the Group IV: (+) single-stranded RNA viruses--> requires RNA-dependent RNA
examples discussed in class from four Baltimore polymerase to make a template for mRNA and genome replication
classification groups: Picornavirus (+RNA)
Example:
Picornavirus
A picornavirus inserts its (+) strand RNA through the receptor and reproduction
occurs entirely in the cytoplasm
A key step is the early translation of a viral gene to make RNA-dependent RNA
polymerase
~A -RNA strand is made from which more +RNA strands are synthesized by the
RNA-dependent RNA polymerase
~The +RNA is used as mRNA for translation of viral proteins and is packaged as the
viral genome
6.f Understand the basic replication cycles of the Group V: (-) single-stranded RNA viruses--> require RNA-dependent RNA
examples discussed in class from four Baltimore polymerase to make mRNA and replicate its genome
classification groups: Influenza virus (-RNA)
Example: Influenza virus
Influenza is enveloped (derived from cell membrane when released from the cell)
~Membrane fusion of the viral envelope with the endosome membrane releases
the RNA genome segments into the cytoplasm
Viruses must package RNA-dependent RNA polymerase with the (-) RNA genome
since it cannot be translated to produce the viral RNA polymerase
~The (-) strand is the template and the (+) strand is the sense strand (mRNA)
