8. Viruses & Virology Flashcards
A virus particle is made up of __________.
RNA only
a nucleic acid and protein
protein only
DNA only
Correct Answer:
a nucleic acid and protein
Incorrect. Viruses are minimal particles and cannot function on their own.
The protein shell surrounding the genome of a virus is called a(n) __________.
cylinder
icosahedron
capsomere
capsid
Correct Answer:
capsid
Incorrect. The shell is a protein structure composed of many identical units.
In the laboratory, animal viruses are generally grown in __________.
culture media
animal cell culture
plants
bacteria
End of Question 3
animal cell culture
4 The plaque assay is a method for __________.
quantifying bacteria
quantifying viruses
quantifying Archaea
quantifying algae
quantifying viruses
After infection and during the eclipse period, __________.
infectious viruses are detected in the culture medium
viruses burst from the infected cell
virus DNA is being reverse transcribed
infectious viruses cannot be detected in the culture medium
Correct Answer:
infectious viruses cannot be detected in the culture medium
Incorrect. The name of this period is a reflection of what is observed in the laboratory.
What do virus particles attach to?
the nucleus
the bacterial cell wall
a receptor on the cell surface
the cytoplasmic membrane
Correct Answer:
a receptor on the cell surface
Incorrect. Viruses attach to a molecule that is specific for virus-host interaction and is found on the cell’s surface.
Viruses present in seawater have been observed by using __________.
fluorescence microscopy
polymerase chain reaction
atomic force microscopy
light microscopy
fluorescence microscopy
Bacteriophages T2 and T4 have a complex structure consisting of __________.
a capsid with head, tail, and tail fibers
RNA, DNA, and protein
a cylindrical capsid
an icosahedral capsid
Correct Answer:
a capsid with head, tail, and tail fibers
Incorrect. Bacteriophage structure is more complicated than structures of typical animal viruses.
A strategy used by T4 bacteriophage to control transcription by host cell RNA polymerase is __________.
modification of the promoter regions of host cell genes
modification of RNA polymerase specificity to recognize only virus-encoded promoters
denaturation of host RNA polymerase
modification of the internal cell environment
Correct Answer:
modification of RNA polymerase specificity to recognize only virus-encoded promoters
Incorrect. This strategy involves modification of a key enzyme in transcription.
In temperate phages such as lambda, the virus __________.
replicates and then bursts from the host cell
establishes a stable relationship with the host cell and does not destroy it
modifies the host RNA polymerase
attaches to the outside of the host cell but does not enter it
establishes a stable relationship with the host cell and does not destroy it
The envelope of an enveloped animal virus is derived from __________.
the host’s cell wall
the outer membrane of a gram-negative bacterium
the host’s nuclear membrane
the host’s cytoplasmic membrane
The envelope of an enveloped animal virus is derived from __________.
Your Answer:
the host’s cytoplasmic membrane
A unique feature that is characteristic of retroviruses is __________.
a capsid with head, tail, and tail fibers
both DNA and RNA in the genome
the enzyme reverse transcriptase
RNA in the capsid
Correct Answer:
the enzyme reverse transcriptase
Incorrect. Retroviruses have a unique method for integrating into host cell DNA.
All of the following are DNA viruses, EXCEPT __________.
tobacco mosaic virus
parvovirus
hepadnavirus
adenovirus
tobacco mosaic virus
Which of the following environments contains the highest number of viruses?
oceans
air
freshwater lakes
soil
oceans
15 What is meant with “burst size”?
the number of virions released per cell
the size of a bacterium before phages are released
the number of bacteria infected with bacteriophages at any given time
the size of a virion
the number of virions released per cell
