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Microbiology 2110 > Viruses Exam 4 Microbiology > Flashcards

Viruses Exam 4 Microbiology Flashcards

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Biology 101 flashcards
1
Q

Virus

A

genetic element that can multiply only in a living (host) cell

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2
Q

Virus is latin for

A

poison

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3
Q

Viruses are

A

the most abundant biological entities on earth

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4
Q

Viruses infect what cells

A

bacteria, algae, fungi, protozoa, plants, and animals

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5
Q

Viruses needs

A

host cells for everything

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6
Q

Viruses have

A

their own nucleic acid genome

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7
Q

Virion

A

the infectious virus particle, the viral genome surrounded by a protein coat

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8
Q

The cause of viral infections are

A

Unknown

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9
Q

Louis Pasteur

A

hypothesized that rabies was caused by a living thing smaller than bacteria

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10
Q

They developed a vaccine for rabies in

A

1884

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11
Q

Dmitri Ivanovski and Martinus Beijernick showed that

A

a disease in tobacco (plant virus)

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12
Q

Loeffler and Frosch discovered

A

The animal virus causing foot and mouth disease in cattle

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13
Q

How did viruses originate

A

Progressive Hypothesis (genetic material capable of moving within a genome)
Escaped genes (Genetic fragments escaped from cells  developed protective coating  reenter cells to hijack machinery to reproduce )

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14
Q

Regressive Hypothesis aka Reductive evolution

A

Reduces the amount of gene that it carries in its genome… Adopts a parasitic lifestyle

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15
Q

Are viruses organisms, are they alive

A

They are nonliving and noncellular
Outside of the host cell they lack most features of life

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16
Q

What role did viruses play in the evolution of life

A

Shape the way cells, tissues, bacteria, plants, and animals have evolved

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17
Q

Human genome containing sequences that came from viruses

A

8%

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18
Q

Bacterial DNA containing viral sequences

A

10 to 20% od bacterial dna

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19
Q

Obligate intracellular parasites

A

Cannot multiply unless they invade a specific host cell and instruct its genetic and metabolic machinery to make and release new viruses

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20
Q

Animal viruses were classified on the basis of

A

their hosts and the diseases they caused (Old System)

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21
Q

Newer classification systems emphasize the following

A

Hosts and disease they cause
Structure
Chemical composition
Similarities in genetic makeup

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22
Q

International Committee on the Taxonomy of Viruses:

A

8 orders and 38 families (another 84 families not yet assigned to any order)

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23
Q

Viruses are obligate intracellular parasites of

A

bacteria, protozoa, fungi, algae, plants, and animals

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24
Q

Viruses are

A

ubiquitous in nature and had major impact on development

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25
Q

The size of viruses

A

Ultramicroscopic , ranging from 20nm up to 1000 nothin much diameter

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26
Q

Structure of viruses

A

Noncellular , very compact and economical

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27
Q

Nucleic acids can either be

A

Dna or Rna but not both

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28
Q

Molecules (Spikes)

A

are on the surface and gives them high specificity for attachment to the host cell

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29
Q

Viruses multiply by

A

taking control of host cell’s genetic material

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30
Q

Which is NOT a potential origin method of viruses

A

Pre-life Hypothesis

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31
Q

How much of the human genome consists of viral sequences?

A

8%

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32
Q

Which of the following is False about viruses

A

They cannot infect algae

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33
Q

What component are viruses missing?

A

Ribosomes

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34
Q

Resemblance to cells

A

IT AINT NO RESEMBLANCE

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35
Q

Viral componet

A

External coating
Core Containing nucleic acids (DNA or RNA)
Matrix proteins and enzymes (occasionally)

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36
Q

Capsid

A

the protein shell that surrounds the genome of a virus

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37
Q

Naked

A

viruses have no other layers

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38
Q

Enveloped

A

viruses have an outer layer consisting of a phospholipid bilayer (from host cell membrane) and viral proteins

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39
Q

Nucleocapsid

A

nucleic acid + protein in enveloped viruses

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40
Q

Spikes

A

can be found on naked or enveloped viruse

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41
Q

Spikes allow

A

viruses to dock with host cells

42
Q

Viral capsids

A

Most prominent feature of viruses

43
Q

Capsomeres

A

identical protein subunits.. make up viral capsids

44
Q

Capsomeres spontaneously

A

self assemble into the finished capsid

45
Q

Two primary types of Capsids

A

Helical
Icosahedral

46
Q

Complex capsids

A

are never enveloped.
only found in the viruses that infect bacteria

47
Q

Enveloped viruses

A

Take a bit of the cell membrane when they are released from a host cell

48
Q

Enveloped viruses can bud from

A

Cell membrane
Nuclear envelope
Endoplasmic reticulum

49
Q

Viruses with a complex capsid infect what type of organism

A

Bacteria

50
Q

The viral envelope is

A

more flexible than the capsid so enveloped viruses are pleomorphic

51
Q

Genome

A

the sum total of the genetic information carried by an organism

52
Q

Why do viruses have such a small amount of genes

A

Possess only the genes needed to invade host cells and redirect their activity

53
Q

Escherichia coli has

A

4,000 genes

54
Q

Humans have

A

21,000 genes

55
Q

Having a larger genome allows…

A

cells to carry out the complex metabolic activity necessary for independent life.

56
Q

Viruses typically posses

A

nly the genes needed to invade host cells

57
Q

Double stranded

A

Linear or circular

58
Q

RNA VIRUSES can be double stranded but

A

more often single-stranded

59
Q

Positive-sense RNA:

A

ready for immediate translation

60
Q

Negative-sense RNA:

A

must be converted before translation can occur

61
Q

Segmented

A

individual genes exist on separate pieces of RNA  similar to human chromosomes

62
Q

Retroviruses

A

carry their own enzymes to convert RNA -> DNA

63
Q

Multiplication Cycles in Animal Viruses

A

Viruses are minute parasites that seize control of the synthetic and genetic machinery of cells

64
Q

Length of replication

A

cycle varies from 8 hours in polioviruses to 36 hours in herpesviruses

65
Q

Adsorption

A

A virus can invade its host cell only through making an exact fit with a specific host molecule

66
Q

Host range of Adsorption

A

Hepatitis B: Liver cells of humans
Poliovirus: Intestinal and nerve cells of primates
Rabies: various cells of all mammals

67
Q

Direct fusion of the viral envelope with the host cell membrane:

A

Envelope merges directly with the cell membrane

68
Q

Penetration and Uncoating
The flexible cell membrane of the host is

A

penetrated by the whole virus or its nucleic acid

69
Q

Penetration through endocytosis

A

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

70
Q

SYnthesis- DNA viruses

A

Enter the host cell’s nucleus and are replicated and assembled there

71
Q

Synthesis- RNA Viruses

A

Replicated and assembled in the cytoplasm

72
Q

Synthesis- Retroviruses turn their

A

RNA genomes into DNA

73
Q

Assembly

A

virus is put together using “parts” manufactured during the synthesis process

74
Q

Release

A

the number of viruses released by infected cells is variable, controlled by:
Size of virus
Health of the host cells

75
Q

Virions released by infected cells vary

A

Poxvirus infected cell: 3,000 to 4,000
Provirus infected cells: 100,000 virions
Immense Potential for rapid

76
Q

Carrier relationships

A

cell harbors the virus and is not immediately lysed
Can remain latent in cytoplasm

77
Q

Provirus

A

Viral DNA incorporated into the DNA of the host

E.g. Measles virus. HIV.

78
Q

Chronic latent state:

A

Periodically become activated under the influence of various stimuli
Ex. Herpes

79
Q

Transformed cells

A

Increased rate of growth
Changes in their chromosomes
Changes in cell’s surface molecules
Capacity to divide indefinitely

80
Q

Oncoviruses: mammalian viruses capable of initiating tumors

A

Papillomaviruses
Herpesviruses
Hepatitis B virus

81
Q

General phases of the animal viral replication cycle EXCEPT: Adhesion
Penetration
Uncoating
Synthesis
Assembly
Release

A

Adhesion

82
Q

During which phase of the animal viral replication cycle do we see nucleic acid replication and protein production

A

Synthesis

83
Q

Bacteriophage “bacteria eating”

A

Contain double stranded DNA, some contain rna at times

84
Q

Bacteriophage “bacteria eating”

A

Contain double stranded DNA, some contain rna at times

85
Q

Bacteria that bacteriophages infect

A

More often pathogenic for humans

86
Q

Every bacterial species is parasitized by…

A

various specific bacteriophages

87
Q

T-even Bacteriophage

A

Most studied

88
Q

T Even bacteriophage infects

A

Escherichia coli

89
Q

Lysogeny

A

a condition in which the host chromosome carries bacteriophage DNA

90
Q

Temperate phages do

A

Undergo absorption and penetration

91
Q

Temperate phages do not

A

undergo replication or release

92
Q

Viral DNA enters an inactive prophage state:

A

Inserted into bacterial chromosome -> Copied during normal bacterial cell division

93
Q

Viral DNA enters an inactive prophage state:

A

Inserted into bacterial chromosome -> Copied during normal bacterial cell division

93
Q

Viral DNA enters an inactive prophage state:

A

Inserted into bacterial chromosome -> Copied during normal bacterial cell division

94
Q

Induction : Lysogeny

A

prophage in a lysogenic cell becomes activated and progresses directly into viral replication and the lytic cycle

95
Q

The Role of Lysogeny in Human Disease

A

phage genes in the bacterial chromosome can cause the production of toxins or enzymes that the bacterium would not otherwise have

96
Q

Lysogenic conversion

A

when a bacterium acquires a new trait from its temperate phage

97
Q

corynebacterium diphtheriae - lysogenic temperate phage

A

diphtheria toxin

98
Q

When phage nucleic acid is incorporated into the nucleic acid of its host cell and is replicated when the host DNA is replicated, this is considered part of which cycle?

A

lysogenic phase

99
Q

A virus that undergoes lysogeny is a/an _________.

A

Temperate phage

100
Q

Which of the following is incorrect about prophages?

A

Cause lysis of host cells

Microbiology 2110 (4 decks)

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