Chapter 13 Mastering Microbiology
During a lytic replication cycle, what action does a phage take to ensure that its host bacterium does NOT continue synthesizing cellular molecules? The phage integrates its DNA into the host cell DNA. The host DNA is released from the cell. A phage traps the host DNA in an endosome. Phage enzymes degrade the bacterial DNA.
Phage enzymes degrade the bacterial DNA
Viruses can be grown in all of the following EXCEPT __________. tissue culture sterile nutrient agar live animals embryonated eggs
Sterile nurtrient agar
Once entry into the bacterial cell has been achieved, the next step in a lytic replication cycle is _____.
Synthesis
In a lytic cycle of replication, release of phages involves _____.
The bacteria cell bursting open
How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?
The host cell dies during the lytic stage
The infectious cycles of enveloped animal viruses and temperate bacteriophages are most similar because __________.
The infected cell may live for a long time
A major difference between the lytic and lysogenic cycles of phage replication is that during the lysogenic phase _____.
The phage genome inserts itself into the host genome
You have isolated bacterium that contains a prophage. Which of the following is true concerning the prophage? New phages are being produced. The phage particles did not attach properly to their host cells. The phage is in the lytic cycle. The phage is in the lysogenic cycle.
The phage is in the lysogenic cycle
Which of the following is NOT a way in which viruses differ from all other living things? They cannot respond to environmental stimuli through metabolic changes. They live inside host cells. They cannot self-replicate. They do not grow.
They live inside host cells
How are viruses different from cells?
They require a host in order to reproduce
What is the function of the structural elements of a virus?
To package and protect the viral genome
What factor may induce a prophage to enter the lytic cycle?
UV light
Lysogenic viral DNA integrating into the host genome is referred to as
A prophage
Contact between a phage and its bacterial host occurs by _____.
A random collision
Lysogeny is associated with all of the following EXCEPT __________. bacteriophages a prophage animal viruses increasing virulence of host bacterium
Animal viruses
A phage T4 particle that has lost its tail fibers will have a replication cycle that is blocked at which of the following stages? entry synthesis attachment assembly
Attachment
What portion of bacteriophage T4 enters E. coli?
Only the T4 genome enters the bacterial cell
Which of the following is an essential component of all viruses? ribosomes capsid DNA envelope
Capsid
Which of the following types of enzymes is necessary for the replication of most double-stranded DNA (dsDNA) viruses? reverse transcriptase cellular DNA polymerase RNA-dependent RNA polymerase viral RNA polymerase
Cellular DNA polymerase
Which of the following is NOT represented in viral classification schemes? genus class family specific epithet
Class
All of these are steps in the lytic cycle of a temperate bacteriophage. Which happens second? attachment release assembly entry
Entry
Lysozyme is important for which of the following stages of lytic replication in bacteriophage T4? synthesis entry and release assembly attachment
Entry and release
Which of the following events might trigger induction of a temperate bacteriophage? Exposure to UV light Bacterial conjugation Normal cell division of an infected cell An infected cell entering the logarithmic phase of growth
Exposure to UV light
Put the following viral structures in order, from simplest to most complex: I. virion II. capsomere III. capsid IV. nucleocapsid
II,III,IV,I
The envelope found in some virus particles differs from the cytoplasmic membrane of cells in that __________.
It does not perform the physiological functions carried out by the cytoplasmic membrane
What is the fate of the prophage during the lysogenic stage?
It is copied every time the host DNA replicates.
During the lysogenic cycle, it is possible for integrated phage genes to change the characteristics of the host cell. This is known as _____.
Lysogenic conversion
Most viral genomes are much smaller than the genomes of the cells they infect. Which of the following CANNOT be inferred from this statement? Viral genomes can be enclosed in very small capsids. Most viruses can infect only certain types of cells. Viral genomes usually do not encode all of the enzymes or structures necessary for their replication. Viral genomes usually contain fewer genes than cellular genomes.
Most viruses can infect only certain types of cells
