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.
The combination of a virus's protein coat and nucleic acid core is called the ________.
Which of the following statements concerning viruses is FALSE?
Viruses enter a cell to complete the replication they have begun extracellularly.
The outermost layer of a virion fulfills which of the following functions of the virus?
protection and recognition
What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?
The virus would not be able to infect new hosts.
Which of the following events might trigger induction of a temperate bacteriophage?
Exposure to UV light
How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?
The host dies during the lytic stage
What is the fate of the prophage during the lysogenic stage?
It is copied every time the host DNA replicates.
We sometimes are able to generate antibodies (immune system proteins) that bind to and cover up some of the proteins
on the outermost portion of a virus while it is in the bloodstream. This renders the virus unable to reproduce. Which step
of viral replication are antibodies directly preventing?
Enveloped viruses have a layer of lipids surrounding their capsid. This envelope is made mostly of host cell membrane.
In which step does the virus acquire this envelope?
Bacteriophage genes that cause toxin production in a normally harmless bacterial species contribute to which of the
Infections with enveloped animal viruses are similar to lysogenic phage infections because
the infected cell may live for a long time
Lysozyme is important for which of the following stages of lytic replication in bacteriophage T4?
entry and release
You have isolated a specimen of lambda phage in which the protein that suppresses prophage genes has suffered a
significant mutation. Which of the following would you expect to observe in cultures of this virus?
The phage will never enter a lysogenic cycle.
A phage T4 particle that has lost its tail fibers will have a replication cycle that is blocked at which of the following
The number of new bacteriophages released from each infected cell is called the ________.
Poxvirus is assembled in the cytoplasm of the cell instead of in the nucleus, as is the case for the majority of dsDNA
viruses. T or F
Put the following stages of a lytic replication cycle in order, from earliest to latest stages:
Which of the following is associated with the attachment of a bacteriophage to a bacterial cell?
random collisions, chemical attractions, and receptor specificity
The enzyme lysozyme is critical for which of the stages of a bacteriophage T4 infection cycle?
entry and release
The phenomenon of transduction is associated with which of the stages of a bacteriophage infection cycle?
Which of the following events occurs in the lytic cycle of bacteriophage T4 infection but not in the lysogenic cycle?
digestion of host DNA
Why is lysogeny advantageous to a bacteriophage?
the genetic material of the bacteriophage can be passed on to future generations of cells.
Which of the following agents is capable of inducing conversion of a prophage back to a lytic phage?
UV light and X rays
Which of the following would be an appropriate mode of action for a new anticancer drug?
inactivation of an oncogene
________, genes that play a role in proper cell division, may also play a role in some types of cancer.
A(n) ________ is a clear zone on a bacterial lawn where cells have been killed by the activity of a bacteriophage.
Zones of clearing in cell cultures that are the result of virus infection are called plaques. Sometimes "cloudy plaques" are
seen on bacterial cultures infected with bacteriophage. What type of viral infection might cause this appearance?
The normal function of the PrP protein in mammals is believed to be:
assisting in normal synaptic development and function.
How do normal prion proteins (PrP) differ from the infectious prion proteins?
Normal PrP have alpha-helices; infectious PrP have beta-pleated sheets.
How does the number of infectious prions increase?
Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply
Why are the beta-pleated multimers of PrP potentially pathogenic?
The multimers are more stable and resistant to protease.
Which of the following conditions in humans is linked to bovine spongiform encephalopathy?
Variant Creutzfeldt-Jakob disease
Where does the name "scrapie" come from?
The prion disorder causes infected sheep to scrape against objects until their skin is raw.