Chapter 6 Flashcards
1
Q
The bacteria responsible for tuberculosis, cholera, and anthrax were identified by Robert ______.
A
Koch
2
Q
Viruses can infect which of the following?
A
Human, bacterial, or plant cells
3
Q
Viruses are composed of which of the following?
A
DNA or RNA
External coating
4
Q
Which of the following activities are not characteristics of viruses?
A
Replicate independently
React to environmental factors
Maintain homeostasis
Metabolize food
5
Q
Which term best describes viruses?
A
Ultramicroscopic
6
Q
True or false: The cause of polio was identified in the late 1800s.
A
False
7
Q
Much of the credit for our knowledge of viruses must be given to experiments with viruses that infect ______ and ______.
A
Bacteria; plants
8
Q
Which of the following describes viruses?
A
Non-living, infectious agent
9
Q
Which type of microscope is usually used to examine viruses?
A
Electron
10
Q
Which structure immediately encloses viral nucleic acid?
A
Capsid
11
Q
Which of the following relate to all viruses?
A
Lack of synthetic machinery
Nucleic acid
12
Q
The term “naked” used in describing viruses implies which of the following?
A
No envelope
13
Q
A protein subunit that forms the viral capsid is a(n) ______.
A
Capsomer
14
Q
Which best describes the shape of a helical virus?
A
Spiral
15
Q
Identify all of the components of a nucleocapsid.
A
Nucleic acid
Capsid
16
Q
A virus that does not have a covering surrounding its capsid is a(n) ______ virus.
A
Naked
17
Q
What term is used to describe the capsid of a virus which has 20 equally spaced panels of capsomers forming a symmetrical structure?
A
Icosahedral
18
Q
Most enveloped viruses are which of the following?
A
Animal viruses
19
Q
Capsomers are composed of which macromolecule?
A
Proteins
19
Q
What is true regarding the viral envelope and the membrane of its host?
A
Spikes may be present on the viral envelope.
Viral glycoproteins are present in the host membrane but not in the viral envelope.
20
Q
Influenza, measles, and rabies are viruses that have a(n) ______ shaped capsid.
A
Helical
21
Q
Together the viral capsid and nucleic acid is referred to as the ______.
A
Nucleocapsid
22
Q
What term is used to describe the viral proteins which protrude from the envelope and aid in attachment to host receptors?
A
Spikes
23
Q
Many animal viruses will acquire which of the following from the host cell’s membrane?
A
Envelope
23
Poliovirus and adenovirus have a capsid arranged in a symmetrical polygon structure called a(n) ______.
Icosahedron
24
The viral envelope is compositionally different from the membrane of a non-infected host cell because of the presence of which of the following?
Viral proteins
25
Protruding glycoproteins of a virus that are responsible for binding to a host cell are called peplomers or ______.
Spikes
26
What is the main function of the viral capsid and envelope?
Protection
27
What term is used to describe the capsid of a virus which has 20 equally spaced panels of capsomers forming a symmetrical structure?
Icosahedral
27
Which viruses have capsids that are atypical and more intricate than those of helical or icosahedral viruses?
Complex
28
Which of the following viral groups contains some members that have a complex structure, with polyhedral capsid heads and helical tails?
Bacteriophages
29
A virus could contain a genome of which of the following?
RNA only
DNA only
30
True or false: Icosahedral viruses are also known as complex viruses.
False
31
If the main purpose of the viral capsid and envelope is the protection of viral nucleic acids, what are they protected from?
Chemicals
32
Which of the following is probably the least responsive to the environment?
Virus
33
Single-stranded RNA genomes that have to be converted to the complementary strand of RNA before they can be translated into proteins are found in ______-strand RNA viruses.
Negative
34
Which of the following describes bacteriophages?
Helical tail
Complex
Polyhedral capsid head
35
HIV is described as a(n) ______ because it synthesizes DNA from RNA using reverse transcription.
Retrovirus
36
Why must living cells carry a larger genome than viruses?
They must be able to carry out metabolic processes that sustain independent life.
36
A general concept of all viruses is that they require a host ______ in order to replicate.
Cell
36
Viruses contain either ______ or ______ as their nucleic acid.
DNA; RNA
37
Which preformed enzyme is involved in the synthesis of DNA from RNA in retroviruses, such as HIV?
Reverse transcriptase
38
Viruses with single-stranded RNA genomes that can be directly translated into proteins are called ______-strand RNA viruses.
Positive
39
Which viral stage occurs first?
Adsorption
40
The influenza virus has an RNA genome that is referred to as ______, because individual genes exist in separate RNA molecules.
Segmented
41
If a virus were to infect a host cell but the cell's enzymes had been denatured, could the virus still replicate?
No, because the virus relies on host enzymes and machinery.
42
What term is used to describe when a virus initially "sticks" to the host cell?
Adsorption
43
What is common to replicase and reverse transcriptase?
They are preformed viral proteins.
44
Which of the following viral structures must recognize host cell structures for adsorption to occur?
Spike proteins
45
Which term describes the tissue specificities of animal viruses for certain body cells?
Tropisms
46
Identify the two main methods that a virus can use to gain entry into an animal cell.
Endocytosis of the virus
Fusion of the viral envelope and the cell membrane
46
The limitations of the type of cell that a virus can invade is defined by the _____ range.
Host
47
List the correct order of viral life cycle phases, placing the first phase at the top.
Adsorption, penetration/uncoating, synthesis, assembly, release
48
Most viral ______ in enveloped viruses are composed of glycoproteins and are used to attach to cells.
Spikes
49
A virus is engulfed into an endosome during the process of ______.
Endocytosis
50
Which is most important for attachment of a virus to a host cell?
Viral specificity for host receptors
51
The process of _______ occurs when viruses lose their envelope during penetration into a host cell or when the capsid and/or envelope is/are dissolved within a vacuole.
Uncoating
52
Which of the following is a term used to describe the different host cells which a virus can infect?
Host range
53
Most DNA viruses will assemble within the host cell's ______.
Nucleus
54
Which term describes the process of a virus losing its capsid and exposing viral nucleic acids to the immediate environment?
Uncoating
55
The two main processes by which viruses penetrate host cells are engulfment, also known as ______, and direct fusion.
Endocytosis
55
Tropisms are tissue specificities of animal viruses for certain body cells, e.g., the hepatitis B virus targets the ______ and the mumps virus targets ______ glands.
Liver; salivary
56
Which term is used to describe the process in which a virus is engulfed by a cell in a vacuole or vesicle?
Endocytosis
57
Where are most DNA viruses replicated and assembled within the host cell?
Nucleus
58
True or false: Most RNA viruses are replicated in the nucleus of the host cell.
False
59
To replicate, viruses with negative-strand RNA molecules must synthesize positive-strand RNA using ______ as a template.
Negative-strand RNA
60
During the ______ step in the viral multiplication cycle, the genetic material is packaged into capsids to make virions.
Assembly/maturation
61
Two ways in which newly assembled viruses are released from host cells are through ______ or exocytosis by enveloped viruses, and through ______ (rupture) by naked viruses.
Budding; Lysis
62
Although there are some exceptions, most RNA viruses are replicated in the _____.
Cytoplasm
63
What is the source of the necessary enzymes for the replication of RNA viruses?
The host cell or the RNA virus
64
Budding of enveloped viruses allows the viruses to be shed ______.
Gradually
65
Which is a simple translation of cytopathic?
Cell damage
66
Which of the following describes the process of various viral "parts" coming together to produce complete virions?
Assembly
67
Using a microscope, you observe some cells which have multiple nuclei because a virus has caused normal cells to fuse together. What is this observation called?
Cytopathic effect
67
Naked viruses are released from animal cells by which of the following methods?
Lysis
68
Which types of viruses are released by budding?
Enveloped viruses
69
Which of the following terms describes viruses in the carrier state within the host cells?
Persistent infections
70
What term is used to specifically describe the types of viruses that infect bacteria?
Bacteriophage
71
Virus-induced damage to the cell that alters its microscopic appearance is referred to as a(n) ______ effect.
Cytopathic
72
In which way do enveloped viruses typically leave their host cell?
Budding
73
Which of the following is used to describe the phage DNA that is latently incorporated into the bacterial host genome?
Prophage
74
Diagnostically, if cytopathic effects are seen, what does this indicate?
Active viral infection
75
The persistence of bacteriophage DNA within a host chromosome is ______.
Lysogeny
76
Which type of infection includes cells that escape destruction by harboring the virus in some form?
Persistent infection
77
Phages can serve as transporters of bacterial genes from one bacterium to another in a process called ______.
Transduction
78
Which of the following tests can detect and amplify minute amounts of viral nucleic acid in a sample?
PCR
79
Who discovered bacteriophages in 1915?
Twort and d'Herelle
80
A bacteriophage that incorporates itself into the host genome as a lysogenic prophage is a(n) ______ phage.
Temperate
81
Lysogeny is best described as which of the following?
Integration of the viral genome into the host chromosome
82
It is well known that ______ have no effect on treating viral infections.
Antibiotics
83
Genes for toxin production and drug resistance can be transferred between bacteria by bacteriophages during which process?
Transduction
84
Why do antiviral drugs often have side effects in host cells?
Antiviral drugs block viral replication by targeting host cell functions.
85
Which is the main test done to diagnose an HIV infection?
Detection of specific antibodies in a patient's blood
86
Any virus that specifically infects bacteria is called a(n) ______.
Bacteriophage
87
Prions are composed of what molecule?
Protein
88
Which of the following is used to describe the phage DNA that is latently incorporated into the bacterial host genome?
Prophage
89
Which of the following is associated with Creutzfeldt-Jacob disease?
Presence of prions in nervous tissues
Transmission from the handling of autopsy tissues
90
Which of the following is not effective treatment for viral infections?
Antibiotics
91
A naked strand of RNA that is only expressed in the presence of hepatitis B virus is called the ______ agent.
Delta
92
True or false: It is common for some antiviral drugs to have negative side effects in people because the drugs target host cell metabolic functions.
True
93
Which of the following tests can detect and amplify minute amounts of viral nucleic acid in a sample?
PCR
94
Which of the following best describes a prion?
Proteinaceous infectious agent
95
Which disease is associated with prions?
Creutzfeldt-Jacob disease (CJD)
96
Which prion-associated spongiform encephalopathy is marked by dementia, impaired senses, and uncontrolled muscle contractions?
Creutzfeldt-Jakob disease
97
AAV can only replicate in cells infected with ______.
Adenovirus
