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MycoViro > Chapter 29 - General Properties of Viruses > Flashcards

Chapter 29 - General Properties of Viruses Flashcards

0
Q

It is acquired when the viral nucleocapsid buds through a cellular membrane in the course of maturation

A

Lipid

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1
Q

Lipids in viral membranes are derived from?

A

Host cell

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2
Q

Occurs only at sites where virus-specific proteins have been inserted into the host cell membrane

A

Budding

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3
Q

Proteins that are protruding from the envelope and exposed on the external surface of the virus particle

A

Viral glycosylated proteins

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4
Q

Proteins that are underneath the envelope that anchor the particle together

A

Viral unglycosylated proteins

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5
Q

Viruses that are sensitive to treatment with ether and other organic solvents

A

Lipid-containing viruses

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6
Q

Viruses that are generally resistant to ether

A

Nonlipid-containing viruses

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7
Q

Viral envelopes contain ________

A

glycoproteins

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8
Q

Enzymes that cleave DNA at specific nucleotide sequences

A

Restriction endonucleases

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9
Q

The entire infectious unit is termed ________.

A

virion

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10
Q

True or false. The viruses are inert in the extracellular environment.

A

True

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11
Q

What encases and stabilizes the viral nucleic acid against the ECE and facilitates the attachment and penetration by the virus

A

Capsid

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12
Q

The viruses that attack bacteria

A

Bacteriophages

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13
Q

Morphologic units on the surface of icosahedral virus particles that represent clusters of polypeptides

A

Capsomeres

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14
Q

A virus particle that is functionally deficient in some aspect of replication

A

Defective virus

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15
Q

Basic building blocks of the coat

A

Structural units

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16
Q

A single folded viral polypeptide chain

A

Subunit

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17
Q

Two theories of viral origin

A

Derived from DNA or RNA nucleic acid components

Degenerate forms of intracellular parasites

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18
Q

Performed early in virus identification

A

Genome sequencing

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19
Q

Basis of Classification

A
  • Virion morphology
  • Virus genome properties
  • Genome organization and Replication
  • Virus protein properties
  • Antigenic properties
  • Physicochemical properties
  • Biologic properties
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20
Q

Virus family names have the suffix

A

-viridae

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21
Q

Genus names carry the suffix

A

-virus

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22
Q

The ______________________________________ had organized more than 4000 animal and plant viruses

A

International Committee on Taxonomy of Viruses

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23
Q

Ex. of heavy metal stain to emphasize surface structure

A

Potassium phosphotungstate

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24
Q

The heavy metal permeates the virus particle like a cloud and brings out the surface structure of viruses by virtue of ___________

A

“Negative staining”

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25
Q

The typical level of resolution

A

3-4 nm

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26
Q

Uses virus samples quick frozen in vitreous ice

A

Cryoelectron microscopy

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27
Q

Can provide atomic resolution info, generally at a level of 0.2-0.3 nm

A

X-ray crystallography

28
Q

Types of arrangement of morphologic subunits

A

Cubic symmetry
Helical symmetry
Complex structures

29
Q

The most efficient arrangement for subunits in a closed shell

A

Icosahedral pattern

30
Q

Describe the icosahedron

A

20 faces (each an equi triangle), 12 vertices, fivefold, threefold, and twofold axes of rotational symmetry, vertex units have five neighbors (pentavalent) and others six (hexavalent)

31
Q

How many identical subunits on the surface of an icosahedron

A

60

32
Q

Physical appearance of most viruses with icosahedral symmetry

A

Spherical

33
Q

Involved in the condensation of the nucleic acid into a form suitable for packaging

A

Cellular histones

34
Q

“__________________” on viral nucleic acid are involved in assembly into virus particles

A

Packaging sequences

35
Q

Expression of ______ proteins from cloned genes often results in self-assembly and formation of empty virus-like particles.

A

capsid

36
Q

Viral architecture where protein subunits are bound in a periodic way to the viral nucleic acid, winding it into a helix

A

Helical symmetry

37
Q

True or false. It is possible for “empty” helical patterns to form.

A

False

38
Q

All known examples of animal viruses with helical symmetry contain (a. DNA b. RNA) genomes.

A

b. RNA

39
Q

Classic attributes of viruses

A

Small size

Ability to pass through filters

40
Q

Most widely used method for estimating particle size

A

Direct observation in the electron microscope

41
Q

Another method in determining particle size aside from the use of the EM

A

Sedimentation in the ultracentrifuge

42
Q

Virus range in diameter from about

A

20 nm to 300 nm

43
Q

Particles with a twofold difference in diameter have an ___________ difference in volume

A

eightfold

44
Q

What virus has a greater mass, the poxvirus or the poliovirus?

A

Poxvirus

45
Q

Their major purpose is to facilitate transfer of the viral nucleic acid from one host cell to another.

A

Structural proteins

46
Q

Fxns of structural proteins

A
  • protect the viral genome against inactivation by nucleases
  • participate in the attachment of the virus particle to a susceptible cell
  • provide the structural symmetry of the virus particle
47
Q

An enzyme in retroviruses that makes a DNA copy of the viral RNA

A

Reverse transcriptase

48
Q

An enzyme carried by viruses with negative-sense RNA genome that is needed to copy the first mRNAs

A

RNA polymerase

49
Q

All major (a. DNA b. RNA) viral groups have a linear or circular configuration

A

a. DNA

50
Q

True or false. The isolated RNA of the negative-sense RNA viruses is infectious.

A

False

51
Q

Hypothesized the existence of infectious agents too small to be seen by a light microscope

A

Jacob Henle

52
Q

People responsible for sterile culture

A

Louis Pasteur and Robert Koch

53
Q

German; described a non-fungal cause of tobacco mosaic disease; performed limiting dilution and determined that it was not a toxin

A

Adolf Mayer

54
Q

Discovered the first filterable human infectious agent in cuba

A

Walter Reed

55
Q

Cannot replicate on its own; needs to utilize host cell

A

Obligate intracellular parasite

56
Q

genome + capsid

A

naked virus

57
Q

genome + capsid + envelope

A

Enveloped virus

58
Q

Carrier of genetic material; either RNA or DNA but not both

A

Genome

59
Q

Classification of genome

A
  • segmented

- non-segmented

60
Q

Classification of DNA/RNA

A
  • double stranded

- single stranded

61
Q

Movement of positive (+) coiling

A

Counterclockwise

62
Q

Movement of negative (-) coiling

A

Clockwise

63
Q

Icosahedral structure often posses _____ viruses

A

naked

64
Q

An example of an enveloped virus having an icosahedral capsid

A

Herpes virus

65
Q

May have arisen from transposable elements

A

Retroviruses

66
Q

Different wild isolates of the same virus

A

Strain

67
Q

Distinct strain of the same virus based upon known genetic difference

A

Type

68
Q

A virus that behaves differently in the laboratory than the wild type due to unknown reasons

A

Variant

MycoViro (9 decks)

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