Chapter 13 practice
In animal virus replication, an uncoating step is needed to release the nucleic acid from the capsid. Why is this step not needed in bacteriophage replication?
Bacteriophages inject their DNA into the host cell.
What bacterial enzyme is used by the virus for replicating its nucleic acid?
DNA polymerase
During viral infection of a host cell, which is the third step of the process?
Release of nucleocapsid into host cytoplasm
The general steps in viral replication (in order) are
adsorption, penetration, synthesis, assembly, release.
Viruses that infect bacterial cells are called ______.
bacteriophages
After entry of the bacteriophage into the host cell, a phage enzyme
breaks the host DNA into fragments
A positive (+) strand of RNA
can directly act as mRNA.
When the bacteriophage transfers bacterial DNA into a recipient bacterial cell, this DNA
can integrate into the chromosome
Every virus particle contains ______.
either DNA or RNA
term that describes a virus that has a lipid bilayer (derived from the host cell) surrounding its capsid.
enveloped virus
All viruses can infect any cell type or tissue type.
false
Generalized transduction is so called because specific bacterial genes are transferred during this process.
false
In the lysogenic stage of phage replication, the host cell is lysed.
false
Bacteriophages adsorb or attach
only to members of the same bacterial species
A major difference in the replication of animal viruses and bacteriophages is the ______ step.
penetration
After host cell DNA is broken down by a viral enzyme
phage DNA is replicated and phage coat proteins are produced.
A difference between plasmids and fragments of DNA that have been transferred between cells is
plasmids can replicate independently
Viral capsids are composed of ______.
protein
Phage DNA encodes for the proteins of the viral capsid and
regulatory proteins that direct the production and assembly of the capsid proteins.
All of the following could serve as receptors for phage attachment EXCEPT
ribosomes
The advantageous genes that can be transferred by transduction are genes for
sugar fermentation, toxin production, drug resistance
In viral entry by endocytosis
the host cell's cytoplasmic membrane surrounds the whole virion and forms a vesicle.
what can cause a phage in the lysogenic stage to revert to the lytic stage?
ultraviolet light
Removal of the capsid to release the virus nucleic acid into the host cytoplasm is called ______.
uncoating
In order for viruses to enter host cells, they must bind to receptors on the host cytoplasmic membrane.
true
More than one mechanism of viral entry into a host cell exists.
true
The negative (-) sense strand of RNA
is used to synthesize more (+) strands.
Once inside the host cell, viral DNA directs production of _______.
new viral particles
Which of the following is required to maintain a lysogenic state?
A repressor protein
The T-even bacteriophages such as T2 and T4 infect
Escherichia coli.
What are the two entry mechanisms used by enveloped viruses?
Fusion and endocytosis
How does bacteriophage DNA get into the host cell?
It is injected
A bacteriophage initially associates with which bacterial structure?
The bacterial cell wall
statement that best describes the role of viral surface proteins or spikes.
Viral spikes provide means of attachment to host cell surface.
Generalized transduction occurs when
a bacteriophage packages a piece of bacterial DNA during replication
During maturation or formation of phage particles
a few phage heads may surround fragments of host bacterial DNA
The capsid of a virus is
a protein shell that surrounds the nucleic acid
The basic parts of a bacteriophage are
an isohedral head, tail, tail pins, and fibers
Viral spikes
attach specifically to host cell receptors
The final step in T2 bacteriophage infection results in:
lysis of the bacterial cell and release of new viral particles.
What term describes the type of bacteriophage infection cycle where the bacteriophage DNA is inserted into the host cell DNA as a prophage and the infected bacteria can continue to grow and divide?
lysogenic
Bacteriophages involved in generalized transduction are ______ phages.
lytic
Viral cycles that end in release of the new phages and immediate destruction of the host bacterial cell are referred to as ______.
lytic
What term describes the type of bacteriophage infection in which the host bacteria are lysed and killed as a result of the infection?
lytic
When present, of what is the viral envelope composed?
mainly lipid
Almost immediately upon entry, the viral nucleic acid alters the gene expression of the host cell.
true
Bacteriophage DNA directs the degradation of the bacterial host cell's DNA.
true
Both enveloped and non-enveloped (naked) viruses can enter a cell by endocytosis.
true
Generalized transduction involves the transfer of phage genes from one bacterial cell to another.
false
Once a phage becomes lysogenic, it will remain lysogenic and never be lytic again.
false
T-even phages can replicate independently of a host cell.
false
In transduction, bacterial DNA is transferred to a new cell when
it is injected by the virus