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Microbiology > Chapter 6 - An Introduction To Viruses > Flashcards

Chapter 6 - An Introduction To Viruses Flashcards

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
Q

What is the viral envelope composed of?

A

Composed of the membrane system of the host

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26
Q

What helps the virus to attach to hosts cells?

A

The viral envelope

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27
Q

What are protruding glycoproteins essential for attachment to the host cell?

A

Spikes

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28
Q

What are regular membrane proteins replaced with?

A

Viral proteins

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29
Q

Define genome.

A

The full complement of DNA and RNA carried by a cell

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30
Q

Viruses contain one or the other but never both.

A

DNA or RNA

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31
Q

What is Positive-sense RNA?

A

Single-stranded RNA genomes ready for immediate translation into proteins

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32
Q

What is Negative-sense RNA?

A

RNA genomes that need to be converted into the proper form to be made into proteins

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33
Q

All viruses must carry genes for ___________ and ____________, regulating actions of the host, and packaging ____________.

A

viral capsid
genetic material
mature viruses

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34
Q

What does enzyme Polymerases do?

A

Synthesizes DNA and RNA

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35
Q

What does enzyme Replicases do?

A

copy RNA

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36
Q

What does enzyme Reverse transcriptase do?

A

synthesizes DNA from RNA

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37
Q

Retroviruses do what with the host’s tRNA molecules?

A

“borrow”

38
Q

What is the first general phase in the life cycle of animal viruses?

A

Absorption

39
Q

What is the second general phase in the life cycle of animal viruses?

A

Penetration

40
Q

What is the third general phase in the life cycle of animal viruses?

41
Q

What is the fourth general phase in the life cycle of animal viruses?

42
Q

What is the fifth general phase in the life cycle of animal viruses?

43
Q

What is the sixth general phase in the life cycle of animal viruses?

A

Release from the host cell

44
Q

What is absorption?

A

Invasion begins when the virus encounters a susceptible host and adsorbs specifically to receptor sites on the cell membrane

45
Q

Hepatitis B only infects what kinds of cells?

A

liver cells of humans

46
Q

What cells does poliovirus infect?

A

Intestinal and nerve cells of primates

47
Q

A virus can invade its host cell only through?

A

Making an exact fit with a specific host molecule

48
Q

Define Endocytosis

A

Entire virus is engulfed by the cell and enclosed in a vacuole or vesicle

49
Q

Define Uncoating

A

Enzymes in the vacuole dissolve the envelope and capsid, releasing the virus into the cytoplasm

50
Q

Where do RNA viruses replicate?

51
Q

Where do DNA viruses replicate?

52
Q

What varies depending on whether the virus is a DNA or RNA virus?

53
Q

What does the viral nucleic acid takes control over?

A

The host’s synthetic and metabolic machinery

54
Q

How are enveloped viruses liberated?

A

By budding or exocytosis

55
Q

What are Inclusion bodies?

A

Compacted masses of viruses or damaged cell organelles in the nucleus or cytoplasm

56
Q

What is Syncytia (singular, syncytium)?

A

Fusion of multiple host cells into single large cells containing multiple nuclei

57
Q

What is an infection called when the cell harbors the virus and is not immediately lysed?

A

Persistent Infections

58
Q

What is a provirus?

A

Viral DNA incorporated into the DNA of the host

59
Q

What is Chronic latent state?

A

Periodic activation after a period of viral inactivity

60
Q

What viruses are estimated by Experts to cause up to 13% of human cancers?

A

Oncogenic viruses

61
Q

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?

A

Transformation

62
Q

What does a Bacteriophage do?

A

Parasitize every known bacterial species and often make the bacteria they infect more pathogenic for humans

63
Q

What goes through similar stages as animal viruses and is most widely studied bacteriophage?

A

“ T-even bacteriophage or known as T-2 and T-4

64
Q

What is the Lytic phase or lytic cycle?

A

Life cycle of bacteriophage that ends in destruction of the bacterial cell

65
Q

What is Lysogenic cycle?

A

Bacteriophage becomes incorporated into the host cell DNA

66
Q

What has the ability to undergo adsorption and penetration but do not immediately undergo replication or release?

A

Temperate phages

67
Q

What is an inactive state in which phage DNA is inserted into the host chromosome?

68
Q

What is induction?

A

Activation of a prophage in a lysogenic cell to progress directly into viral replication and the lytic cycle

69
Q

Some _______ _______ carry genes that enhance _______. Once inserted into the bacterial chromosome can cause the production of _______ or enzymes that cause ________ in the human.

A

Lysogenic phage
Virulence
Toxins
Pathology

70
Q

What is the acquisition of a new trait from a temperate phage and responsible for the diphtheria toxin, cholera toxin, and botulism toxin?

A

Lysogenic conversion

71
Q

What happens during the absorption cycle of a bacteriophage?

A

Precise attachment of special tail fibers to cell wall.

72
Q

When happens during the release from host cell stage for bacteriophage?

A

Cell lyses when viral enzymes weaken it

73
Q

What are In Vito methods?

A

Viral cultivation in lab animals or embryonic bird tissues

74
Q

What are In vitro methods?

A

Viral cultivation in cell or tissue culture

75
Q

What are the primary purposes of Viral Cultivation?

A

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
Q

What is an in vitro virus cultivation system?

A

Cell culture or tissue culture

77
Q

Most viruses are propagated through?

A

Cell culture

78
Q

What are plaques?

A

Clear, well-defined patches in the cell sheet

79
Q

When do plaques develop?

A

Develops when viruses released from an infected cell radiate out to surrounding cells and infect them

80
Q

How do plaques spread?

A

Infection spreads gradually and symmetrically from the original point of infection

81
Q

What does plaque manifest?

A

Macroscopic manifestations of cytopathic effects

82
Q

What are spongiform encephalopathies Implicated in?

A

Implicated in chronic, persistent disease in humans and animals

83
Q

How does spongiform encephalopathies resembles?

A

Brain tissue removed from affected animals resembles a sponge

84
Q

What are prions?

A

Distinct protein fibrils deposited in brain tissue of affected animals

85
Q

What is a common feature of spongiform encephalopathies?

86
Q

What does Creutzfeldt-Jakob Disease (CJD) affect?

A

Afflicts the central nervous system of humans

87
Q

What causes gradual degeneration and death?

A

Creutzfeldt-Jakob Disease (CJD)

88
Q

What is the sheep and mink elk version of Creutzfeldt-Jakob Disease (CJD) called?

89
Q

What is the cow version of Creutzfeldt-Jakob Disease (CJD) called?

A

Bovine spongiform encephalopathy

90
Q

What mutates at a rapid rate?

91
Q

Scientists focus on developing _______ against viruses since so few __________ are available and ________ are ineffective.

A

vaccines
antiviral drugs
antibiotics

92
Q

What is a naturally occurring human cell product and is used with some success in preventing and treating viral infections?

A

Interferon

Microbiology (8 decks)

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