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Microbiology > Chapter 6 - An Introduction To Viruses > Flashcards

Chapter 6 - An Introduction To Viruses Flashcards

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1
Q

Viruses can infect what type of cells?

A 
Bacteria
Algae
Fungi
Protozoa
Plants
Animals
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2
Q

Rather than organisms viruses have?

A

Infectious particles

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3
Q

Viruses are not called dead or alive instead they are called?

A

Active or inactive

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4
Q

Obligate intracellular parasites Cannot multiply unless they?

A

Invade a specific host cell

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5
Q

What must instruct the genetic and metabolic machinery of the host cell to make and release new viruses?

A

Obligate intracellular parasites

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6
Q

What has basic structure of protein shell (capsid) surrounding nucleic acid core, lack enzymes for most metabolic processes, and are not cells?

A

Viruses

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7
Q

What is smaller than the average bacterium and electron microscopes are required to detect them?

A

Viruses

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8
Q

What lacks protein-synthesizing machinery?

A

Viruses

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9
Q

A virus needs only these required parts to invade and control a host cell?

A

External coating

Core containing nucleic acids

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10
Q

What is the shell that surrounds the nucleic acid and protects DNA that allows for attachment to host cell?

A

Viral Capsid

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11
Q

What is a capsid and nucleic acid that are combined together?

A

Viral Nucleocapsid

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12
Q

Not every virus has this structure and is usually a modified piece of the host cell membrane?

A

Viral Envelope

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13
Q

What is compromised primarily of lipids?

A

Viral envelope

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14
Q

A naked virus consists of?

A

Consist only of a nucleocapsid

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15
Q

Where are spikes found?

A

Found on both naked and enveloped viruses

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16
Q

What projects from either the nucleocapsid or envelope?

A

Spikes

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17
Q

What allows viruses to dock with their host cells?

A

Spikes

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18
Q

What is allows a fully formed virus able to establish infection in a host?

A

Virion

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19
Q

What has a single type to several types and is an identical protein subunits that spontaneously self assemble to form the capsid?

A

Capsomeres

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20
Q

What is a Helical capsid?

A

Rod-shaped capsomeres that form a continuous helix around the nucleic acid

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21
Q

What is a Icosahedral capsid?

A

Three-dimensional, 20-sided figure with 12 evenly spaced corners

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22
Q

Describe a Helical capsid.

A

Helical capsids have rod-shaped capsomers that bond together to form a series of hollow discs resembling a bracelet.

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23
Q

Where are complex capsid found?

A

Bacteriophage, the viruses that infect bacteria

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24
Q

What has multiple types of proteins and takes shapes that are not symmetrical?

A

Complex Capsids

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25
What is the viral envelope composed of?
Composed of the membrane system of the host
26
What helps the virus to attach to hosts cells?
The viral envelope
27
What are protruding glycoproteins essential for attachment to the host cell?
Spikes
28
What are regular membrane proteins replaced with?
Viral proteins
29
Define genome.
The full complement of DNA and RNA carried by a cell
30
Viruses contain one or the other but never both.
DNA or RNA
31
What is Positive-sense RNA?
Single-stranded RNA genomes ready for immediate translation into proteins
32
What is Negative-sense RNA?
RNA genomes that need to be converted into the proper form to be made into proteins
33
All viruses must carry genes for ___________ and ____________, regulating actions of the host, and packaging ____________.
viral capsid genetic material mature viruses
34
What does enzyme Polymerases do?
Synthesizes DNA and RNA
35
What does enzyme Replicases do?
copy RNA
36
What does enzyme Reverse transcriptase do?
synthesizes DNA from RNA
37
Retroviruses do what with the host’s tRNA molecules?
“borrow”
38
What is the first general phase in the life cycle of animal viruses?
Absorption
39
What is the second general phase in the life cycle of animal viruses?
Penetration
40
What is the third general phase in the life cycle of animal viruses?
Uncoating
41
What is the fourth general phase in the life cycle of animal viruses?
Synthesis
42
What is the fifth general phase in the life cycle of animal viruses?
Assembly
43
What is the sixth general phase in the life cycle of animal viruses?
Release from the host cell
44
What is absorption?
Invasion begins when the virus encounters a susceptible host and adsorbs specifically to receptor sites on the cell membrane
45
Hepatitis B only infects what kinds of cells?
liver cells of humans
46
What cells does poliovirus infect?
Intestinal and nerve cells of primates
47
A virus can invade its host cell only through?
Making an exact fit with a specific host molecule
48
Define Endocytosis
Entire virus is engulfed by the cell and enclosed in a vacuole or vesicle
49
Define Uncoating
Enzymes in the vacuole dissolve the envelope and capsid, releasing the virus into the cytoplasm
50
Where do RNA viruses replicate?
Cytoplasm
51
Where do DNA viruses replicate?
Nucleus
52
What varies depending on whether the virus is a DNA or RNA virus?
Mechanism
53
What does the viral nucleic acid takes control over?
The host’s synthetic and metabolic machinery
54
How are enveloped viruses liberated?
By budding or exocytosis
55
What are Inclusion bodies?
Compacted masses of viruses or damaged cell organelles in the nucleus or cytoplasm
56
What is Syncytia (singular, syncytium)?
Fusion of multiple host cells into single large cells containing multiple nuclei
57
What is an infection called when the cell harbors the virus and is not immediately lysed?
Persistent Infections
58
What is a provirus?
Viral DNA incorporated into the DNA of the host
59
What is Chronic latent state?
Periodic activation after a period of viral inactivity
60
What viruses are estimated by Experts to cause up to 13% of human cancers?
Oncogenic viruses
61
What is it called when a Virus carries genes that directly cause cancer and produces proteins that induce a loss of growth regulation in the cell?
Transformation
62
What does a Bacteriophage do?
Parasitize every known bacterial species and often make the bacteria they infect more pathogenic for humans
63
What goes through similar stages as animal viruses and is most widely studied bacteriophage?
“ T-even bacteriophage or known as T-2 and T-4
64
What is the Lytic phase or lytic cycle?
Life cycle of bacteriophage that ends in destruction of the bacterial cell
65
What is Lysogenic cycle?
Bacteriophage becomes incorporated into the host cell DNA
66
What has the ability to undergo adsorption and penetration but do not immediately undergo replication or release?
Temperate phages
67
What is an inactive state in which phage DNA is inserted into the host chromosome?
Prophage
68
What is induction?
Activation of a prophage in a lysogenic cell to progress directly into viral replication and the lytic cycle
69
Some _______ _______ carry genes that enhance _______. Once inserted into the bacterial chromosome can cause the production of _______ or enzymes that cause ________ in the human.
Lysogenic phage Virulence Toxins Pathology
70
What is the acquisition of a new trait from a temperate phage and responsible for the diphtheria toxin, cholera toxin, and botulism toxin?
Lysogenic conversion
71
What happens during the absorption cycle of a bacteriophage?
Precise attachment of special tail fibers to cell wall.
72
When happens during the release from host cell stage for bacteriophage?
Cell lyses when viral enzymes weaken it
73
What are In Vito methods?
Viral cultivation in lab animals or embryonic bird tissues
74
What are In vitro methods?
Viral cultivation in cell or tissue culture
75
What are the primary purposes of Viral Cultivation?
To isolate and identify viruses in clinical specimen, prepare viruses for vaccines, and Do detailed research on viral structure, multiplication cycles, genetics, and effects on host cells
76
What is an in vitro virus cultivation system?
Cell culture or tissue culture
77
Most viruses are propagated through?
Cell culture
78
What are plaques?
Clear, well-defined patches in the cell sheet
79
When do plaques develop?
Develops when viruses released from an infected cell radiate out to surrounding cells and infect them
80
How do plaques spread?
Infection spreads gradually and symmetrically from the original point of infection
81
What does plaque manifest?
Macroscopic manifestations of cytopathic effects
82
What are spongiform encephalopathies Implicated in?
Implicated in chronic, persistent disease in humans and animals
83
How does spongiform encephalopathies resembles?
Brain tissue removed from affected animals resembles a sponge
84
What are prions?
Distinct protein fibrils deposited in brain tissue of affected animals
85
What is a common feature of spongiform encephalopathies?
Prions
86
What does Creutzfeldt-Jakob Disease (CJD) affect?
Afflicts the central nervous system of humans
87
What causes gradual degeneration and death?
Creutzfeldt-Jakob Disease (CJD)
88
What is the sheep and mink elk version of Creutzfeldt-Jakob Disease (CJD) called?
Scrapie
89
What is the cow version of Creutzfeldt-Jakob Disease (CJD) called?
Bovine spongiform encephalopathy
90
What mutates at a rapid rate?
Viruses
91
Scientists focus on developing _______ against viruses since so few __________ are available and ________ are ineffective.
vaccines antiviral drugs antibiotics
92
What is a naturally occurring human cell product and is used with some success in preventing and treating viral infections?
Interferon

Microbiology (8 decks)

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