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microbiology > taxonomy - viruses > Flashcards

taxonomy - viruses Flashcards

1
Q

viruses are group into families that end in —-

A

viridea

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2
Q

viruses are given a genus name that end in —

A

virus

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3
Q

viruses are given a species name usually in —

A

English

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4
Q 
classification is based on: 
1)
2)
3)
4) 
5)
A

1) nature of the host –> animal, plant, etc
2) type of disease caused –> e.g. centric, leukaemia, pneumonia
3) life cycle
4) naked or enveloped
5) type of nucleic acids and strandedness

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5
Q

life cycle depends on the —-

A

genome

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6
Q

the Baltimore classification scheme is based on:

why is it useful?

A

the type of genome

it is useful because the type of genome will dictate the replication mechanism

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7
Q

name the 2 configurations of the RNA genome

A

plus configuration and minus configuration

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8
Q

adsorption

A

attachment of the virus to specific receptors on the surface of the cell

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9
Q

plant viruses are usually introduced onto the host by ——-, or following ——

A

insect vectors, mechanical damage

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10
Q

penetration

A

virus genome enter the cell

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11
Q

—- and —– viruses , the complete vision may enter the cell

A

enveloped , naked

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12
Q

in —- viruses, the envelope may be left outside the cell such that only the —- may enter

A

enveloped, nucleocapsid

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13
Q

in naked viruses the —- may be left outside

A

capside

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14
Q

uncoating

A

removal of the envelope and pr the capsid by host enzymes, sometimes within lysosomes (in eukaryotes)

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15
Q

explain the mechanisms in which penetration may happen

A

1) naked viruses that have no envelope bind then inject their DNA inside the cell e..g bacteriophage
2) enveloped viruses bind then the 2 envelopes fuse together and that will be destroyed inside the host cell - frees the genome * viral glycoproteins remain in the cytoplasmic membrane
3) animal cells use endocytosis - the enveloped virus bind to the membrane and that will trigger endocytosis: the cell picks up the new thing in a new envelope so now the virus is in 2 membranes. they then get sent to the lysosome which degrade the capsid and the genome is released in the cytoplasm

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16
Q

latent period

A

eclipse + maturation

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17
Q

eclipse

A

time necessary for the host cells to replicate the viral genome and to synthesize the viral components

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18
Q

maturation

A

time needed for the different components to be assembled

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19
Q

release (rise period)

+mechanisms by which it can happen

A
  • visions are detected outside the cell
  • lysis: virus encoded proteins damage the cytoplasmic membrane. in bacteria, a virus encoded protein destroys the peptidoglycan layer
  • budding: *enveloped viruses
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20
Q

burst size

A

number of virions released

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21
Q

how does release by budding occur

A

accumulation of the viral protein in the cytoplasm of the host cell –> the proteins result in a cluster of proteins in the membrane –> the viral capsid will bind there (underneath) and pushed through the membrane –> they fuse –> the virus is eventually released
PAGE 8

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22
Q

most bacteriophages are —, and — ; some may possess envelopes

A

dsDNA, naked

23
Q

name the 2 types of bacteriophages

A

1) virulent phage: infection of host cells always leads to replication resulting in host cell lysis –> lytic pathway e.g. T4
2) temperate phage: have 2 options 1) lytic pathway 2) lysogenic pathway: becomes a prophage –> the genome of the virus will integrate the chromosome of the bacteria –> cell diviosn –> when nutrients are low (stationary phase) –> the virus gets out of the chromosome –> enters the lytic pathway e.g. lambda

24
Q

T4 adsorption

A

attaches to the core region of LPS by the tail fibres

25
Q

what happens after T4 adsorption

A

the tail sheet contracts, forcing the central core through the outer membrane. then tail lysozyme digest the peptidoglycan layer, forming a small pore. the phage DNA is the injected in to the cytoplasm of the host cell
PAGE 14

26
Q

infection by temperate phage results in a:

A

prolonged latent state of infection (lysogeny)

27
Q

prophage

A

phage genome within the host cell chromosome

28
Q

lysogen

A

bacterium that contains the prophage

29
Q

explain the mechanisms in which lambda replicates

A

1) the phage genome is dsDNA and linear with cohesive ends
2) the ends cyclize together forming a circle
3) circle can be inserted into the genome at attgama - the enzyme lambda integrates catalyzes integration of the phage genome at this side

30
Q

where is lambda integrase encoded

A

on the phage genome

31
Q

classify phage MS2

A

ssDNA, plus strand

32
Q

SSDNA replication

A

minus strand must be synthesized fist by RNA replicase –> RNA depended RNA pol

33
Q

the genome of DNA viruses is usually replicated in the —-

A

nucleus

34
Q

the genome of RNA viruses is replicated in the —-

A

cytoplasm

35
Q

herpes is a —- virus

A

DNA

36
Q

penetration of DNA genome viruses

A

fusion of the cell’s cytoplasmic membrane with the virus envelope. nucleocapsid is transported to the nucleus where viral DNA is uncoated

37
Q

transcription/translation of DNA viruses

A

1) immediate early proteins: like transcription factors and in some cases virus specific RNA pol
2) delayed early proteins: viral specific DNA pol, and other viral proteins necessary for replication
3) late proteins: nucleocapsid

38
Q

assembly of DNA viruses occurs in the —-, envelope is added via a —– process though the —- membrane of the nucleus. the complete visions are the secreted out of the cell by —— pathways

A

nucleus, budding, inner, ER Golgi

39
Q

name some examples of plus strand RNA viruses

A

coronavirus, poliovirus, hepatitis A

40
Q

in poliovirus, the plus strand RNA serves as a template for synthesis of ——. what does this do?

A

a large poly protein, cleaved not proteins –> each smaller subunit has a diff fxn 1) RNA replicase: relocated RNA of the virus first be making a negative strand that will be used to make more positive strand 2) structural proteins 3) proteins that help cleave the poly proteins (proteases)

41
Q

example of minus strand RNA viruses

A

measles, rabies, infleunza

42
Q

ssDNA minus strand replicaiton

A

the virion needs to have the RNA pol by itself so when it gets injected the minus strand becomes positive and gets replicated based on that

43
Q

example of dsDNA viruses

A

rotavirus

44
Q

what is retrovirus

A

RNA viruses examples include HIV

  • cancer causing viruses include: rous sarcoma virus
  • plus strand
  • ssRNA
45
Q

components of retrovirus

A

1) integrase
2) proteases
3) reverse transcriptase –> RNA dependent DNA pol that RNA –> DNA

46
Q

how does retrovirus enter the cell

A

ssRNA –> inserted into the cell –> virus gets inside the genome of the host like temperate bacteriophage –> in order to get instead into the genome it needs to get converted into DNA –> reverse transcription –> dsDNA genome version goes to the nucleus and gets instead –> the host can transcribe the genome into mRNA to make proteins

47
Q

consequences of viral infection in unicellular organisms

A

release of virions

48
Q

consequences of viral infection in multicellular organisms

A

1) cell death: following by the releases of visions via lysis
2) if release is slow –> budding of the virus through the membrane – doesn’t kill the cells –> called persistent infection: produces viruses slowly e.g. HIV
3) latent infection: the cell is infected same wth the genome but for some reason the virus is not replicated e.g. herpes (infected but not replicated) ** may lead to lysis
4) transformation into tumor cells
5) cell fusion

49
Q

cell fusion results in —— that have —— —— and are usually —- lived

A

hybrid cells, chromosomal aberration, short

50
Q

fusion often occurs in —– viruses

A

enveloped

51
Q

cell fusion between the infected cell and another releases —-

A

nucleocapsids

52
Q

transformation

A

a cell that has acquired immortality, characterized by uncontrolled replication.

53
Q

T/F

both DNA and RNA viruses are known to cause tumours in animals and humans

A

true

54
Q

name the 4 different mechanisms by which transformation happens

A

1) transduction
2) insertion of a strong promoter
3) inactivation of a tumor suppressor gene
4) expression of a viral protein that induces transformation (DNA virus)
- go over each in your notes

microbiology (9 decks)

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