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Viruses Flashcards

1
Q

Define virome.

A

sum of viral populations in an ecosystem

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2
Q

What is the virus to bacteria ratio for marine life?

A

1:100

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3
Q

What is the virus to bacteria ratio for aquatic life?

A

1:1000

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4
Q

Viruses are critical in (blank) and (blank).

A

carbon balance, recycling of nutrients

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5
Q

What are viruses?

A

obligate pathogens

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6
Q

Define “host range.”

A

a particular group of host species that the virus infects

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7
Q

Define viron.

A

a bag of genomic material

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8
Q

List the 4 things virons do.

A

1) must infect host cell
2) undermine the cell’s machinery and direct it to produce viruses
3) consists of nucleic acid contained with a protective capsid
4) codes for 10-1000 genes

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9
Q

Define giant viruses.

A

genomes of double-stranded DNA with 500-2500 genes

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10
Q

What do miniviruses do?

A

infect amoeba’s, can actually become infected by smaller viruses called virophages

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11
Q

Define viroid.

A

extremely simple RNA viruses that infect plants

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12
Q

What are the components of a viroid?

A

naked RNA, no capsid, replicated by host RNA polymerase

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13
Q

How are viroids transmitted?

A

a) sap feeding insects
b) damaged tissues
c) infected seeds

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14
Q

What are prions?

A

shape-changing proteins

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15
Q

Why are prions problematic?

A

they are disease causing infectious proteins that have abnormal conformations

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16
Q

Why are prions so dangerous?

A

they are highly resistant to heat, chemicals, etc, they are also pathogenic and transmissible

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17
Q

What do multiple prion proteins do?

A

aggregate and cause holes in the brain

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18
Q

What are the 2 types of capsid forms?

A

asymmetrical and symmetrical

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19
Q

Give an example of a symmetrical virus.

A

iscoahedal virus (herpes)

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20
Q

What shape is herpes?

A

polyhedral with 20 triangular faces which is a structure that exhibits rotational symmetry

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21
Q

How is the capsid of herpes viruses packaged?

A

packaged with viral DNA, some have envelopes surrounding the capsid

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22
Q

Give an example of a filamentous virus?

A

ebola virus

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23
Q

Describe a filamentous virus.

A

capsid consists of a long tube of monomers with genome coiled inside

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24
Q

Define asymmetrical viruses.

A

have large genomes surrounded by several layer and the core envelope is studded with spike proteins

25
What do asymmetrical viruses contain?
a large number of accessory that are required immediately upon infection of host cell
26
What can be DNA or RNA but not both?
viral genomes
27
Describe dsDNA and ssDNA.
sense and antisense DNA, can be linear, circular or segmented
28
What is the classification of viruses based on?
1) genetic material | 2) morphological characteristics
29
What is the Baltimore classification?
it's how mRNA is produced
30
What do retoviruses do?
integrate their genomes into the host genome
31
List some features about retroviruses.
they have +ssRNA, they are RNA reverse transcribing viruses that package their own RT enzyme
32
What does the RT enzyme do?
transcribed +ssRNA to -ssDNA,
33
How is +ssDNA transcribed?
using the host DNA polymerase
34
What ends with viridae?
family name
35
What ends with virus?
genus name
36
How do you grow bacteriophages?
lytic bacteriophages from plaques
37
How do you grow viruses?
culturing viruses require growth in susceptible/appropriate host cells
38
in living animals?
ensures virus strain maintains its original virulence
39
In embryonic cells?
carefully inject virus into developing embryo
40
In a tissue culture?
batch culture, liquid or in transformed/adapted animal cells
41
To commence an infection cycle (black) need to contract and attach to the surface of an appropriate (blank).
bacteriophages, bacterial host cell
42
Cell-surface receptors.
mediate the contact and attachment
43
(blank) have (blank) on their capsids that recognize specific proteins or polysaccharides on their bacterial surface.
phages, proteins/glycolipids
44
What determines the phage tropism?
receptors
45
What cell-surface receptors?
proteins with important functions for the host cell that have been co-opted by the virus
46
How does resistance to phage bacteria occur?
mutating of the amino acid sequences of its surface receptors
47
Attachment: (Stage 1 of bacteriophage lytic cycle)
to a bacterial cell surface receptor
48
Penetration: (Stage 2 of bacteriophage lytic cycle)
of genetic material through cell wall
49
Uncoating: (Stage 3 of bacteriophage lytic cycle)
DNA drawn into the cell
50
Biosynthesis: (Stage 4 of bacteriophage lytic cycle)
temporal regulation of transcription
51
Assembly: (Stage 5 of bacteriophage lytic cycle)
of viron proteins and genomes
52
Release: (Stage 6 of bacteriophage lytic cycle)
+/- lysis of cell membrane
53
Maturation: (Stage 7 of bacteriophage lytic cycle)
final activation of viron proteins
54
List the forms of bacteria and anti-phage defenses.
1) genetic resistance (altered phage receptor proteins) 2) restriction endonucleases (cleave viral DNA lacking methylation) 3) CRISPR integration of phage DNA sequences
55
C-R-I-S-P-R
Clustered Regularly Interspaced Short Palindromic Repeats
56
What is CRISPR?
its a bacterial immune system that cleaves bacterial DNA
57
What causes many human cancers?
oncogenic viruses
58
What are some examples of oncogenic viruses?
epstein-barr virus and hepatitis C
59
How to oncogenic viruses work?
they transform the host cell to become cancerous because the transformed cell undergoes division

Microbiology (11 decks)

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