1
Q
What is the role of the capsid in a virus?
A
Protects the nucleic acid when the virus is outside of the host cell
The capsid also helps the virus bind to a cell surface and assists in the penetration of the viral DNA or RNA into a suitable host cell.
2
Q
What is a nucleocapsid?
A
The combination of viral nucleic acid and the capsid that encloses it
It is formed during the assembly of the virus.
3
Q
What are the two basic shapes of viral capsids?
A
Helical and icosahedral
Viruses may also be complex, exhibiting more intricate structures.
4
Q
What are spikes on a viral envelope?
A
Exposed proteins essential for attachment of the virus to the host cell
They play a critical role in the infection process.
5
Q
What are complex viruses?
A
Viruses with more intricate structures than helical or icosahedral viruses
Examples include poxviruses and certain bacteriophages.
6
Q
What is the viral genome composed of?
A
Either DNA or RNA, but never both
It carries genes necessary to invade a host cell and redirect the cell’s activity to produce new viruses.
7
Q
True or False: All viruses have an outer envelope.
A
False
Some viruses, such as naked viruses, do not have an outer envelope.
8
Q
What are the general phases in the animal virus multiplication cycle?
A
Adsorption, Penetration, Uncoating, Synthesis, Assembly, Release
These steps outline how viruses replicate and produce new viral particles.
9
Q
What is the Baltimore classification?
A
A system that groups viruses into seven classes based on their nucleic acid, stranded-ness, sense, and method of replication
It helps in understanding the diversity of viruses.
10
Q
Class I viruses are characterized by which type of nucleic acid?
A
Double-stranded DNA (dsDNA)
Examples include Adenoviruses and Herpesviruses.
11
Q
What is the replication method for Class IV viruses?
A
The genome acts directly as mRNA and is translated by host ribosomes
Examples include Coronaviruses and Poliovirus.
12
Q
Fill in the blank: The _______ is a viral component that aids in the binding of the virus to the host cell.
A
spikes
These are essential for the attachment process.
13
Q
What are the two main methods by which animal viruses penetrate host cells?
A
Fusion and Endocytosis
Fusion occurs in envelope viruses, while endocytosis can happen in both enveloped and naked viruses.
14
Q
What does the term ‘tropism’ refer to in virology?
A
The tissue specificity of a virus
It indicates the range of cells a virus can infect.
15
Q
What is the assembly process of animal viruses?
A
Mature virus particles are constructed from a growing pool of parts, with the capsid laid down first as an empty shell
This serves as a receptacle for the nucleic acid strand.
16
Q
What is a key difference between DNA and RNA viruses in terms of replication?
A
DNA viruses are generally replicated and assembled in the nucleus, while RNA viruses are replicated in the cytoplasm
This affects the replication strategies and timing.
17
Q
What type of viruses are classified under Class VI?
A
Positive-sense single-stranded RNA (retroviruses)
An example is HIV.
18
Q
What is the mortality rate of the 1918 Flu Pandemic?
A
10.0%
It infected 30-50 million people.
19
Q
What type of nucleic acids can RNA viruses have?
A
Usually single-stranded, may be double-stranded or segmented
Positive-sense RNA can be translated immediately, while negative-sense RNA must be converted first.
20
Q
How are viruses classified by the International Committee on Taxonomy of Viruses (ICTV)?
A
Into Order, Family, Genus, and Species
As of 2023, there are 27 recognized orders of viruses.
21
Q
What are the main types of viral morphology?
A
Nonenveloped (naked) viruses, enveloped viruses, and complex viruses
Each type has distinct structural features.
22
Q
What is the first step in the assembly of a virus?
A
The capsid is first laid down as an empty shell that will serve as a receptacle for the nucleic acid strand.
23
Q
What is a virion?
A
A fully formed, extracellular virus particle that is virulent and able to establish infection in a host.
24
Q
How do assembled viruses leave the host cell?
A
Either by budding (exocytosis) or cell lysis (rupturing).
25
What occurs during budding?
The nucleocapsid binds to the membrane, which pinches off and sheds the viruses gradually; the cell is not immediately destroyed.
26
What happens during cell lysis?
Viruses are released when the cell dies and ruptures.
27
What are cytopathic effects?
Cell damage altering microscopic appearance, including disorientation of individual cells and gross changes in shape or size.
28
What defines viruses as obligate intracellular parasites?
They are obligate intracellular parasites of bacteria, protozoa, fungi, algae, plants, and animals.
29
What is the size range of viruses?
Ultramicroscopic size, ranging from 20 nanometers up to 450 nm in diameter.
30
What type of nucleic acid can be found in viruses?
Either DNA or RNA, but not both.
31
What are oncogenic viruses?
Viruses that enter the host cell and permanently alter its genetic material, potentially resulting in cancer.
32
What is transformation in the context of viral infection?
The process by which viruses alter the genetic material of a host cell, leading to increased growth and division.
33
What is the lytic cycle in bacteriophages?
The cycle involving full completion of viral infection through lysis and release of virions.
34
What are temperate phages?
DNA phages that undergo adsorption and penetration but do not replicate, inserting their genome into the bacterial genome as inactive prophage.
35
What is lysogeny?
A reversible state of infection where the viral genome is incorporated into the host's genetic material without killing the host cell.
36
What are viroids?
Short pieces of RNA with no protein coat, identified only in plants.
37
What is the role of vaccines in viral disease prevention?
Vaccines stimulate natural defenses within the body and have been developed for common illnesses like smallpox and polio.
38
What are prions?
Misfolded proteins that contain no nucleic acid and are extremely resistant to usual sterilization techniques.
39
What diseases are associated with prions?
Transmissible spongiform encephalopathies, such as Creutzfeldt-Jakob Syndrome in humans and BSE in cattle.
40
What components make up a virus particle?
1. Covering (capsid and envelope) 2. Central core (nucleic acid and matrix proteins).
41
What types of capsid structures exist?
* Helical: Continuous helix of capsomers forming a cylindrical nucleocapsid * Icosahedral: Three-dimensional, symmetrical polygon with 20 sides.
42
What is the difference between naked and enveloped viruses?
Naked viruses have only a nucleocapsid, while enveloped viruses have an additional covering external to the capsid.
43
True or False: Animal viruses cannot undergo lysogeny.
False.
44
___ are the smallest infectious agents
Viruses
45
What is negative staining
Opaque salt to outline the shape of the virus against a dark background and to enhance textural features on the viral surface
46
Positive staining
Used for internal details of specific parts of the virus such as protein or nucleic acid
47
Molecular structure of virus
Regular repeating viruses
48
What can purified viruses form
Large aggregates or crystals of subjected to special treatments
49
Viruses contain parts that are just needed for invading and controlling a host cell such as
External coating and a core containing one or more nucleic acid strands of either DNA or RNA
50
What is a protein capsid
Shell that surrounds the nucleic acid in the central core
51
Together , the capsid and the nucleic acid are referred as the
Nucleocapsid
52
Viruses that only have a nucleocapsid are considered
Naked viruses
53
Out of 20 families of animal viruses , __ are enveloped
13, they posses an additional covering external to the capsid called an envelope
54
Capsid is constructed from a number of identical protein subunits called
Capsomers
55
The shape and arrangement of the capsomers result in the prod. of one or two dif. Types of capsids:
Helical or icosahedral
56
Helical capsule have __ shaped capsomers
Rod, bind tg to form a series of hollow discs resembling a bracelet
57
The nucleocapsids of naked helical viruses are very
Rigid and tightly wound into a cylinder shaped package
58
Enveloped helical nucleocapsids are more ..
Flexible and tend to be arranged as a looser helix w/in the envelope
59
Icosahedron capsid
3 dimensional, symmetrical polygon, w 20 sides and 12 even,y spaced corners
60
During the assembly of a virus , the ___ ___ is packed into the center of the icosahedronforming a ____
Nucleic acid
Nucleoplasid
61
When viruses mostly animal are released from the hostel, they take with them a bit of the host’s __ ___
Membrane system in the form of an envelope.ope
62
Some viruses __ off the cell membrane , others leave via the ___ ___ or the __
___
Bud
Nuclear envelope
Endoplasmic reticulum
63
Even though the envelope is directing the house, it is different because some are all of the regular membrane ___ are replaced
Ribosome
64
What does some proteins form between the envelope and capsid of the virus and glycoprotein (proteins bound to a carbohydrate) remain exposed on outside envelope
A binding layer
65
___ and ___ also responsible for helping to introduce the viral DNA or RNA into a suitable host cell and the by
Capsid and envelop
First by binding to the cell surface and then Persisting in penetration of the viral nucleic acid
66
67
Parts of viral caps and envelope stimulate the ____ system to produce antibodies that can neutralize viruses and protect the whole cells against future infections
Immune
68
Poxiviruses (complex)
Large DNA viruses that lack atypical capsid and are covered by dense layer of Lipo proteins and course fibrils on their outer surface
69
Bacteriophages (complex)
Have a polyhedral capsid bead as well as a helical tail and fibers for attachment to the host cell
70
What is a genome?
Some total of the genetic information carried by an organism 
71
Having a larger genome allows cells to 
Carry out the complex, metabolic activity necessary for independent life
72
What does it mean for RNA to be segmented
Individual genes exist in separate RNA molecules 
73
Viruses cannot multiply until what?
Their nucleic acid has reached their haven inside the host cell
74
Polymerase(viral replication)
Synthesize DNA and RNA and replicate enzymes that copy RNA
75
Which virus can perform reverse transcriptase
HIV
synthesize DNA from RNA
76
What genes do viruses lack
Genes for synthesis of metabolic enzymes
77
Can viruses carry away substances from their host cell?
Yes some of them
Ex ribosomes, tRNA
78
Rhabdoviruses
Bullet shaped envelope
79
Togaviruses
Cloak like envelope
80
Adenovirus first discovered in adenoids (type of tonsil)
81
Hantaviruses
Isolated to Korean prominence oh hantaan
82
Lentiviruses
Slow chronic infections
83
Picornaviruses and hepadnaviruses
Tiny RNA viruses
84
85
What does it mean to say that viruses are ultramicroscopic?
Viruses are too small to be seen with a light microscope
## Footnote
This term indicates that viruses require an electron microscope for visualization.
86
Describe the general structure of viruses.
Viruses consist of genetic material surrounded by a protein coat, and sometimes an envelope
## Footnote
The genetic material can be DNA or RNA.
87
What is the capsid, and what is its function?
The capsid is a protein coat that protects the viral genetic material
## Footnote
It also aids in the attachment of the virus to host cells.
88
How are the two types of capsids constructed?
Capsids can be constructed in two forms: helical and icosahedral
## Footnote
Helical capsids are rod-shaped, while icosahedral capsids have a spherical shape.
89
What is a nucleocapsid?
A nucleocapsid is the combination of the viral genome and the capsid
## Footnote
It is the complete viral particle before the envelope is added, if present.
90
Give examples of viruses with the two capsid types.
Examples include:
* Helical: Tobacco mosaic virus
* Icosahedral: Adenovirus
## Footnote
These examples illustrate the structural differences between the two types.
91
What is an enveloped virus?
An enveloped virus has a lipid membrane surrounding its capsid
## Footnote
The envelope arises from the host cell membrane during viral replication.
92
What are spikes, how are they formed, and what is their function?
Spikes are protein structures on the surface of enveloped viruses
## Footnote
They are formed from viral proteins and facilitate attachment to host cells.
93
What are bacteriophages?
Bacteriophages are viruses that specifically infect bacteria
## Footnote
They often have complex structures, including a head and tail.
94
What is unique about the structure of poxviruses?
Poxviruses have a complex structure with a large, brick-shaped appearance
## Footnote
They differ from other animal viruses due to their size and structural complexity.
95
Explain the characteristics used in viral classification.
Viral classification is based on:
* Type of genetic material
* Capsid shape
* Presence of an envelope
* Host range
## Footnote
These characteristics help categorize viruses into families.
96
How are generic and common names used in viral classification?
Generic names are used for the virus family, while common names refer to specific viruses within that family
## Footnote
This helps in standardizing the naming of viruses.
97
Absorption
Invasion begins when virus finds susceptible hosts and absorbs to receptor it’s on cell membrane (usually attach to glycoproteins)
98
In enveloped viruses what binds to what in the Absorption stage
Glycoprotein spikes spine to the cell membrane receptors
99
A naked nuclear capsids what do they bind to in absorption stage
They use surface receptors on their capsids that adhere to cell membrane receptors
100
What is host range?
When a virus invaded whole cell, but it can only fit a specific hostel since the range of host it can affect in a natural setting is limited
101
So that lack compatible virus receptors are resistant to what? (Host range)
Absorption and invasion by that virus
102
Penetration stage
Penetrate the cell membrane of the whole cell and deliver the viral nucleic acid into the host cells interior
103
What are the two ways of penetration?
Fusion and endocytosis
104
Fusion (penetration)
The viral envelope fuses directly with the whole cell membrane, so it can occur only an envelope viruses
The bits within the adjacent membranes become rearranged, so the nuclepcapsid can be located into the side of plasm for the synthesis phase
105
Endocytosis(penetration)
Can occur to envelope or naked virus
Engulfed entirely into a bicycle called an endosome after it’s initial attachment. Once inside the cell the virus is uncoated
106
107
What does it mean when a virus is uncoated(penetration)
The physical membrane becomes altered so that the viral nucleoid or nucleocapsids can be released into the cytoplasm
108
Synthesis stage
Viral nucleic acid exerts control over hosts metabolism and synthetic machinery
DNA is replicated in hosts cell nucleus
RNA viruses are replicated in cytoplasm
Immediately the nucleus,Eric acid alters gene expression of host and instructs it to synthesize building blocks for new viruses
109
110
What is produced in the synthesis stage
RNA, proteins for capsid, spikes, and viral enzymes
111
Assembly stage
Capsid is first laid down as an empty shell that will serve as a receptacle for the nucleic acid strand
112
Release stage
2 ways to
- nonenveloped and complex viruses in nucleus or cytoplasm are released via lysis
- enveloped viruses are released through budding or exocytosis from the me,Thames of cytoplasm, nucleus, ER, and vesicles
Nucleocapsids bind to membrane which curves completely around and form a small pouch, pinching the pouch off releases the virus w its envelope
113
Cytopathic effects
Virus induced damage to the cell that alters its microscopic appearance
Individual cells can be disorientated (changes in size, shape, or intercellular changes)
114
Inclusion bodies
Compacted masses of viruses or damaged cell organelles in the nucleus and cytoplasm
115
Examination of cells and tissues for ___ effects has been a traditional tool for diagnosing viral infections
Cytopathic
116
Lysis
Splits open and releases mature virions
Hastened by viral enzymes produced late in infection cycle that weaken cell envelop
117
Temperate phages (lysogeny)
Undergo absorption and penetration into the bacteria host, but are not replicated or released immediately
Instead of all DNA and an inactive prophage state
118
119
Propane state (temperate phages)
inserted into the bacterial chromosome
120
Condition in which the host chromosome carries bacteriophage DNA (lysogeny)
Lysogeny
121
Because viral products are not produced the bacterial cells carry __ ___ do not lyse and they appear entirely normal 
Temperate phages
122
Induction(lysogeny)
Prophase and a isogenic cell will be activated and progressed directly into viral replication and the Lydic cycle
123
Is lysogeny less deadly?
Yes, rather than the full lytic cycle and it starts to be an advancement that allows the virus to spread without killing the host
124
Because of the intimate association between the genetic material of the virus and the house pages occasionally serviced transporters of___ genes from one bacterium to another … what is this called
Bacterial
Transduction
125
Transduction is one way that gene for toxin production and drug resistance are transferred between…
Bacteria
126
Viral genomes often encode
Toxins, enzymes, and other factors that can alter the course and outcome of infection
127
Weren’t a bacterium acquires genes from its temperate phage it is called.
Lysogenic conversion
128
What does viral nucleic acid do once it gets into the cell?
It begins to hijack the cellular machinery to replicate and produce viral components.
## Footnote
Viral nucleic acids can either be DNA or RNA, depending on the virus type.
129
What processes are involved in bacteriophage assembly?
The processes include packaging of nucleic acid, assembly of the protein coat, and maturation of the virion.
## Footnote
Bacteriophage assembly occurs after replication of the viral genome.
130
What is a prophage?
A prophage is a dormant form of a bacteriophage that is integrated into the host's genome.
## Footnote
It can remain inactive until activated to enter the lytic cycle.
131
What is lysogeny?
Lysogeny is a process where a bacteriophage integrates its nucleic acid into the host genome and replicates along with it without killing the host.
## Footnote
This can provide immunity to the host against superinfection by similar phages.
132
Compare the main phases in the lytic multiplication cycle of bacteriophages and animal viruses.
Both cycles involve attachment, penetration, biosynthesis, maturation, and release, but the mechanisms of penetration and release differ significantly.
## Footnote
Bacteriophages typically inject their nucleic acid, while animal viruses may enter through endocytosis.
133
Why is penetration different between bacteriophages and animal viruses?
Bacteriophages inject their nucleic acid directly into the host, while animal viruses generally enter the host cell through endocytosis or fusion with the cell membrane.
## Footnote
This results in different mechanisms of entry and may influence the type of cellular response.
134
Areas where virus infected cells have been destroyed, sharp as clear well defined patches in the cell sheet called
Plaques
135
Do antibiotic antibiotics work for viruses?
No, because they are not bacteria
136
The envelope of an animal virus is derived from the _______ of its host cell.
membrane
137
What types of nucleic acid can a virus have?
Either DNA or RNA
## Footnote
Viruses can possess either a DNA genome, an RNA genome, or both in some exceptions.
138
What are the general steps in a viral multiplication cycle?
Adsorption, penetration, synthesis, assembly, and release
## Footnote
These steps outline the typical process by which viruses reproduce within a host cell.
139
A prophage is a/an _______ stage in the cycle of bacterial viruses.
latent
140
How does the nucleic acid of animal viruses enter the host cell?
b and c
## Footnote
This includes both fusion with the cell membrane and endocytosis.
141
In general, where do RNA viruses multiply in the cell compared to DNA viruses?
Cytoplasm, nucleus
## Footnote
RNA viruses typically replicate in the cytoplasm, while DNA viruses usually replicate in the nucleus.
142
What do enveloped viruses carry on their surfaces?
Spikes
## Footnote
These spikes are important for the virus's ability to attach to and enter host cells.
143
Viruses that persist in the cell and cause recurrent disease are considered _______.
latent
144
Viruses cannot be cultivated in _______.
blood agar
145
Clear patches in cell cultures that indicate sites of virus infection are called _______.
plaques
146
Which of these is not a general pattern of virus morphology?
Complex, helical
## Footnote
Common patterns include enveloped helical and icosahedral forms, but complex helical is not standard.
147
Which of these is true of prions?
They cause death of brain cells
## Footnote
Prions are misfolded proteins that lead to neurodegenerative diseases.
Microbiology
flashcards
Decks in class (36)
# Cards
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Chemistry & Biochemistry49
-
Ch 8 Metabolic109
-
Ch. 13 Microbes131
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Ch, 4 Prokaryotes54
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Midterm Prep214
-
Ch 189
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Ch. 2104
-
Ch. 489
-
Practice Test140
-
Scientific Disease Names10
-
Euk Vs Prok167
-
DNA Rep27
-
Lab Practicum19
-
Ch. 5 Eukaryotes245
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Ch. 6147
-
Ch. 9386
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Test 2 Review132
-
#11-51 Cards31
-
Ch. 7285
-
Ch. 11349
-
Ch. 12415
-
Extra 12450
-
Lab Review128
-
Lec 3 Review64
-
Ch 1456
-
Disease Cards 21-28, 52-6825
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Disease Card Quiz177
-
Ch. 15315
-
Ch. 16319
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Final Study Guide174
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#10-20137
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#21-31169
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#32-43155
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#44-54160
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#55-68211
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Ch 1748
