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Applied Biology > Viruses > Flashcards

Viruses Flashcards

1
Q

T/F: viruses infect all living organisms.

: we carry viral genomes as part of out own genetic material

A

both T

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2
Q

virus’ were discovered as

A

an agent that causes tobacco mosaic disease, it could pass through a .2 micro meter filter that retained bacteria

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3
Q

virus sizes range from

A

20-700 nm

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4
Q

giant viruses like pandoraviruses and mimiviruses

A

are hosted by amoebas, are dsDNA viruses, have a large genome >1Mbp >1000 genes, and are up to 1 micrometer

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5
Q

what are viruses

A

are infectious obligate intracellular parasites, they can propagate only by host cells, all viruses make mRNA that is translated by the host cell ribosomes

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6
Q

T/F

  • viruses regulate transport of materials into and out of themselves
  • perform any metabolic reaction
  • they replicate autonomously
A
  • F
  • F
  • F
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7
Q

T/F

  • viruses contain nucleic acid based genome
  • they transfer their genome from one host cell to another
  • they cange over time according to selective pressure
A
  • T
  • T
  • T
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8
Q

a T4 phage only has what cycle

A

lytic cycle

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9
Q

temperature phages like lambda phage have what cycle

A

both the lytic and the lysogenic

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10
Q

give 3 traits of animal viruses

A

~the genome is a type of nucleic acid (DNA/RNA)
~protein capsid
~some of them posses an envelope

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11
Q

are viral genomes large

A

no all viral genomes at small and simple containing few genes

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12
Q

the proteins encoded by viral genome are

A

~protein needed for replicating the genome
~proteins needed for packaging and delivery
~proteins that modify structure and function of host cell

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13
Q

the protein shell is made of

A

one or more subunits (capsomers) arranged in regular arrays

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14
Q

the capsid has what shape

A

helical or icosahedral

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15
Q

functions of the capsid are

A

protect the viral genome during transfer between host , deliver the viral genome, recognize and package newly formed nucleic acid genomes

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16
Q

give 4 traits of the virus’ envelope

A

~ external membrane layer (not in all viruses)
~ lipid bilayer from host cell (budding)
~ protein of the envelope are instead encoded by the viral genome
~ its function is the attachment of the virus to the host cell

17
Q

non enveloped virus’ protection comes from

A

the proteins

18
Q

give 4 traits of naked viruses

A

~ are more environmentally stable and resistant to drying and detergents
~ are resistant to gastric and biliary acids
~ cause host cell lysis when released
~ ex: adenovirus, rhinovirus, rotavirus

19
Q

give 4 traits of enveloped viruses

A

~ are unstable in environment, and easily inactivated by detergents, acids and heat
~ cannot survive in the GI tract
~ exit from host cell by budding
~ ex: influenza virus, HIV

20
Q

which survives longer on hands : enveloped or naked virus

A

naked

21
Q

how are viruses transmitted

A

direct contact, aerosols, insect bites, contaminants in food/water, sexual transmission, blood and blood contaminated material

22
Q

the infectious cycle

A

~ attachment and entry with release of viral genome
~ genome replication and synthesis of viral proteins
~ assembly
~ release

23
Q

viral tropism

A

the type of receptor a virus binds to determines which type of cells and organism will be affected.

24
Q

some viruses need more than on receptor

A

primary receptor CD4m co-receptor chemokine. for HIV

25
Q

HIV causes

A

AIDS

26
Q

retroviruses

A

are enveloped RNA viruses, like rous sarcoma virus and HIV, during infection the viral RNA id converted to dsDNA by the viral protein reverse transcriptase

27
Q

list the 4 steps of the infectious cycle of a retrovirus

A

~ virus enters the cell by membrane diffusion
~ reverse transcriptase make dsDNA
~ the DNA provirus is integrated permanently into the hosts’ genome by viral integrase
~ when proviral DNA is activated new virions are produced

28
Q

what is the effect of lytic infections on cells

A

host are killed by virus release

29
Q

what is the effect of chronic/persistent infections on cells

A

cells may remain infected for a long time and produce viruses at low levels Hepatitis B

30
Q

what is the effect of latent infections on cells

A

the viral genome is kept within cells in a quiescient state but can occasionally activate. cold sores and chicken pox

31
Q

what is the effect of Transforming infections on cells

A

infected cells exhibit altered growth properties that might trigger oncogenesis

Applied Biology (13 decks)

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