Ch.13 Viruses, Viroids, & Prions Part 1 Flashcards

(37 cards)

1
Q

what do viruses infect?

A

infect host cells and exploit them to form new virions

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1
Q

who is susceptible to virus infection?

A

cell types in all taxonomic domains

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2
Q

who discovered viruses?

A

Ivanovsky and Beijernick

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3
Q

what did Ivanovsky and Beijernick discover?

A

tobacco mosaic virus; “non-filterable particles”

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4
Q

what is the size range of viruses?

A

20 to 90 nanometers

0.02 to 0.90 micrometers

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5
Q

what are viruses defined as?

A

defined as acellular, obligate intracellular parasites

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6
Q

define acellular

A

not consisting of cells

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7
Q

defined obligate intracellular parasites

A

can reproduce/replicate only inside a host cell

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8
Q

what do all viruses consist of?

A

nucleic acid (DNA/RNA) in a protein shell, a CAPSID
comprised of capsomere units

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9
Q

what is the 1st step in the viral process?

A

Virus: host recognition

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10
Q

what comes from the host of the virus?

A

DNA polymerase & RNA polymerase (dependent on virus type)
Ribosomes
tRNA’s
nucleotides

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11
Q

what is the structure of capsids?

A

can vary in shape and size;
helical or polyhedral

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12
Q

define genome structure:

A

single or double-stranded DNA or RNA

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13
Q

describe enveloped viruses’ structure :

A

envelope surround capsid

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14
Q

where is the envelope derived from?

A

host plasma membrane

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15
Q

what do envelopes contain?

A

virus-specific proteins including glycoprotein spikes

16
Q

what is the function of glycoprotein spikes?

A

function in host recognition and attachment

17
Q

explain complex virus structure

A

have complicated structures; possess non-capsid protein components

ex: bacterial virus (bacteriophage)

18
Q

viral genomes need what?

A

very specific enzymes

19
Q

viral genes:

A

code for structural components, enzymes used in the life cycle ( viral genome replication/processing)

20
Q

small viruses of viral genome encode?

21
Q

larger viruses of viral genome encode?

22
Q

what does the host range mean?

A

how many different hosts can the virus infect?

23
Q

what are the host ranges?

A

broad (infect many)
Ex: rabies virus

Narrow range(only infects some)
Ex:HIV infects only humans

24
what does infectivity depend on?
virus: host recognition interaction between viral surface proteins and host cell surface molecules
25
what is tissue specificity?
infect certain types of cells or tissue within the host
26
the genome of DNA virus:
can serve as a template for transcription can serves as a template for DNA synthesis
27
the genome of an RNA virus
can serve as a template for translation ---->(+) RNA viruses can serve as a template for mRNA synthesis---> (-) RNA Viruses can serve as a template for DNA synthesis ---> retrovirus
28
what is a viral species?
is a group of viruses sharing the same genetic information and host range
29
the first step of viral infection
host recognition & attachment via recognition/binding of the viral capsid, envelope proteins, or glycoprotein to host cell surface proteins/ glycoproteins
30
the second step of viral infection
genome entry the entire capsid + genome enters the host cell, or only the genome may enter
31
the third step of viral infection
synthesis & virion assembly genome replication, protein synthesis; assembly of virions
32
the 4th step of viral infection
release from host cell---> progeny infect more host cells
33
how are viral species classified?
classified based on genome type and the presence or lack of an envelope
34
what is virions?
complex viral particle
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