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Microbiology > fundamental virology - L6A > Flashcards

fundamental virology - L6A Flashcards

1
Q

what is a virus?

A

a protein shell with genetic material

intracellular parasite

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2
Q

what is a virion?

A

extracellular form of a virus

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3
Q

what is a capsid

A

protein shell surrounding virus

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4
Q

what is a nucelocaspid

A

inner structure of protein + nucleic acid

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5
Q

what is an envelope

A

phospholipid bilayer (derived from host) + proteins

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6
Q

what is a lytic

A

viral infection that kills the host cell

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7
Q

what is lysogenic

A

viral infection where the virus genome integrates into host genome

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8
Q

name 4 ways virus’ spread

A

skin bites

blood transfusions

mucous membranes

breast milk

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9
Q

name 3 spreading ability factors

A

viability in environment

ability to survive in host

resistance to bodily sites

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10
Q

describe a naked virus

A

They lack n external membrane

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11
Q

described and envelope virus

A

has additional lipid coat derived from the host

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12
Q

give 2 examples of a naked virus

A

rhinovirus

poliovirus

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13
Q

enveloped virus examples

A

influenza

HIV

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14
Q

describe structure of virus

A

extremely small

contain few proteins in capsid

precise ordres

cannot be seen with convention microscope

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15
Q

how are viruses classified?

A

based on symmetry

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16
Q

what are the three classifications for viruses?

A
  • helical
  • icosahedral
  • complex
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17
Q

how do we identify helical viruses?

A

length of nucleic acid

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18
Q

what do icosahedral viruses have

A

20 faces and 12 vertices

requires smallest number of capsomeres to build it

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19
Q

viruses can be complex structures with…

A

each part having own structure and symmetry

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20
Q

example of helical virus

A

tobacco mosaic virus

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21
Q

example of icosahedral

A

human papilloma virus

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22
Q

example of complex virus

A

bacteriophage T4

23
Q

what protein do envelopes usually have and what does it do

A

spike protein

binds to and enter cells

24
Q

how do viruses exit cells

A

budding

where they take a part of the host Plasma membrane with them

or cell lysis

25
Q

what can classification of nucleic acid be

A

rna or dna

single or double stranded

26
Q

example of RNA virus

A

HIV

27
Q

example of a DNA virus

A

Hepatitis B

28
Q

what can single stranded viruses be

A

plus

minus

29
Q

what direction do plus stranded run in

A

5’ to 3’

30
Q

what direction do minus stranded run in

A

3’ to 5’

31
Q

what is plus and minus stranded also referred to

A

positive and negative sense

32
Q

can DNA be transcribed immediately?

A

yes

33
Q

what are the 7 categories of the Baltimore classification system/

A

double-stranded DNA viruses (Group I)

single-stranded DNA viruses (Group II)

double-stranded RNA viruses (Group III)

positive single-stranded RNA viruses (Group IV)

negative single-stranded RNA viruses (Group V)

positive single-stranded RNA viruses (Group VI)

positive double stranded DNA viruses (Group VII)

34
Q

what do positive sense RNA genomes have

A

cap at 5’ end and poly A tail at 3’ end

used directly as mRNA

35
Q

describe negative sense RNA genomes

A

first using a virus encoded RNA polymerase a positive sense RNA is made

this is then capped and polyadenylated

used directly as mRNA

36
Q

can viruses metabolise?

A

no

37
Q

what is an example of a key enzyme important for virus life cycle?

A

neuraminidase

38
Q

name the stages for virions to be released

A
  1. attachment
  2. penetration
  3. nucleic acid and protein synthesis
  4. capsid assembly and genome packaging
  5. vision release
39
Q

what is attachment

A

when the virus binds to the cell

40
Q

what is penetration

A

injection of viral nucleic acid into host cell

41
Q

what is nucleic acid and protein synthesis driven by

A

host under viral control

42
Q

where does vision release occur

A

at the cell membrane in multiple ways

43
Q

name the 4 growth phases of the viral life cycle

A

eclipse phase

maturation phase

44
Q

what happens at eclipse phase

A

viral genome and proteins replicated

45
Q

what happens at maturation phase

A

viral nucleic acid and mature viruses accumulate in cell

46
Q

what is burst size

A

number of released viruses

47
Q

what is burst size

A

number of released viruses

48
Q

what changes during a lysogenic infection in virion release

A

after penetration, nucleic acid integrates into the host genome and called a prophage

cells divide and also replicate the viral genome

49
Q

what are the 5 stages of a typical human infection

A
  1. binding and fusion

endocytosis

uncoating

replication ,translation and transcription

assembly and release

50
Q

what are 2 consequences of a virus infection?

A

The infection can be PERSISTENT and not kill the cell but cause continual viral release by budding e.g. HIV

Some viruses can cause a normal cell to become cancerous and this is called TRANSFORMATION e.g. human papilloma virus

51
Q

what is a retrovirus?

A

a virus that has RNA instead of DNA as its genetic material

52
Q

which enzyme do retroviruses use

A

reverse transcriptase to become part of the host cells DNA

53
Q

what must retroviruses make during life cycle

A

a DNA intermediate

Microbiology (15 decks)

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