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Micro 4- Viruses Flashcards

1
Q

general characteristics of viruses

A
  • obligatory intracellular parasites (require living host cells to multiply)
  • contain DNA or RNA
  • contain a protein coat
  • few or no enzymes for metabolism (no ribosomes, no ATP-generating mechanism)
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2
Q

what is a host range

A

most viruses infect specific types of cells in one host, determined by specific host attachment sites and cellular factors required for viral multiplication

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3
Q

how do bacteriophages relate to host range

A

receptor site is part of cell wall, fimbriae, or flagella

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4
Q

viral size

A

range from 20-1000nm in length

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5
Q

what is a virion

A

complete, fully developed, infectious viral particle

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6
Q

viral structure:

nucleic acid

A

DNA or RNA but never both (either ssDNA, dsDNA, ssRNA, or dsRNA)

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7
Q

viral structure:

capsid

A

protein coat

  • composed of capsomeres, protein sub units
  • protects the nucleic acid from nuclease enzymes in biological fluids
  • promotes virus’s attachment to susceptible host cell
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8
Q

viral structure:

envelope

A

lipid, protein, and carbohydrate coating on some viruses

  • covers capsid in some viruses
  • lipid, protein, and carbohydrate coating
  • it is part of the host cell’s plasma membrane in some animal viruses
  • may or may not be covered by spikes
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9
Q

viral structure:

spikes

A

projections from outer surface

  • carbohydrate-protein complexes that project from the surface of the envelope
  • allow viral attachment to host cells
  • means of identification
  • enable certain viruses to clump red blood cells, hemagglutination
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10
Q

why are capsomeres important

A

capsomeres are protein subunits, single or several types

-arrangement of capsomeres is characteristic of a particular type of virus

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11
Q

list of general morphology (shapes)

A
  • helical viruses
  • polyhedral viruses (many sided)
  • enveloped viruses (spherical, helical, or polyhedral)
  • complex viruses (complicated structures)
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12
Q

influenza classification

A

nucleic acid of influenza virus is in several separate segments

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13
Q

examples of helical virus

A

rabies and ebola viruses

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14
Q

examples of polyhedral viruses

A

adenovirus and poliovirus

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15
Q

examples of enveloped viruses and helical

A

influenza

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16
Q

examples of enveloped viruses and polyhedral

A

herpes virus

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17
Q

examples of complex viruses

A

bacteriophages and poxviruses

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18
Q

genus name ends in

A

-virus

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19
Q

family name ends in

A

-viridae

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20
Q

order name ends in

A

-ales

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21
Q

viral species is

A

a group of viruses sharing the same genetic information and ecological niche (host)

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22
Q

explain bacteriophages are grown in bacteria

A

bacteriophages form plaques, which are learnings on a lawn of bacteria on agar surface
-each plaque corresponds to a single virus, can be expressed as plaque-forming units (PFU)/ mL of virus plated

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23
Q

virus growth in living animals (in embryonated eggs)

A
  • virus injected into the egg

- viral growth is signaled by changes or death of the embryo

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24
Q

virus growth in cell cultures

A
  • tissues are treated with enzymes to separate cells
  • virally infected cells are detected via their deterioration, known as the cytopathic effect (CPE)
  • continuous cell lines are used
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25
Q

list of tests for viral identification

A
  • cytopathic effects
  • serological tests (i.e. Western Blotting)
  • nucleic acids (RFLPs, PCR)
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26
Q

western blotting viral identifcation

A

reaction of the virus with antibodies

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27
Q

overview of 2 cycles of bacteriophages

A 
lytic cycle (phage causes lysis and death of host)
lysogenic cycle (phage DNA is incorporated in the host DNA( includes-phage conversion and specialized transduction)
28
Q

list 5 steps of lytic cycle

A
  1. attachment
  2. penetration
  3. biosynthesis
  4. maturation
  5. release
29
Q

lytic cycle step 1:

attachment

A

phage attaches by the fibers to the host cell

30
Q

lytic cycle step 2:

penetration

A

phage lysozyme breaks down the cell wall and injects its DNA

31
Q

lytic cycle step 3:

biosynthesis

A 
production of phage DNA and proteins 
eclipse period (virus is synthesizing viral components)
32
Q

lytic cycle step 4:

maturation

A

assembly of phage particles

33
Q

lytic cycle step 5:

release

A

phage lysozyme breaks the cell wall and host cell membrane lyses

34
Q

lysogeny

A

phage remains latent

35
Q

lysogenic cycle

A

phage DNA incorporates into host cell DNA, attachment and penetration
-originally linear phage DNA forms a circle, recombination of phage DNA with host DNA, prophage

36
Q

results of lysogeny

A

immunity of lysogenic cells to reinfection by same phage

37
Q

phage conversion

A

the host cell exhibits new properties

examples: corynebacterium diphtheria, clostridium botulinum

38
Q

specialized transduction

A

specific bacterial genes transferred to another bacterium via a phage

39
Q

animal viruses multiplication steps

A
  • attachment-viruses attach to cell membrane
  • entry- by receptor mediated endocytosis or fusion
  • uncoating- by viral or host enzymes
  • biosynthesis- production of nucleic acid and proteins
  • maturation- nucleic acid and capsid proteins assemble
  • release- by budding (enveloped viruses) or rupture (non-enveloped viruses)
40
Q

location of biosynthesis steps in DNA viruses

A
  • DNA viruses replicate their DNA in the nucleus of the host using viral enzymes
  • synthesize capsids in the cytoplasm using host cell enzymes
41
Q

list of 5 examples of DNA viruses

A
  1. adenoviridae
  2. poxviridae
  3. herpesviridae
  4. papovaviridae
  5. hepadnaviridae
42
Q

DNA virus:

Adenoviridae

A
  • dsDNA, non-enveloped

- common cold, acute respiratory infections, eye infections (viral conjunctivitis)

43
Q

DNA virus:

Poxviridae

A
  • dsDNA, enveloped

- poxviruses: smallpox, cowpox, skin lesions

44
Q

DNA virus:

Herpesviridae

A
  • dsDNA, enveloped
  • Simplexvirus
  • Varicellovirus
  • Lymphocryptovirus
  • cytomegalovirus
  • roseolovirus
  • rhadinovirus
45
Q

DNA virus:

Papovaviridae

A
  • dsDNA, non-enveloped

- papillomavirus

46
Q

DNA virus:

Hepadnaviridae

A
  • dsDNA, enveloped
  • hepatitis B virus
  • use reverse transcriptase to make DNA from RNA
47
Q

in RNA virus biosynthesis, virus multiplies in the

A

host cell’s cytoplasm using RNA-dependent RNA polymerase

48
Q

ssRNA + strand

A

sense strand

-viral RNA serves as mRNA for protein synthesis

49
Q

ssRNA - strand

A

antisense strand

-viral RNA is transcribed to a + strand to serve as mRNA for protein synthesis

50
Q

list of 5 examples of RNA viruses

A
  1. picornaviridae
  2. togaviridae
  3. retroviridae
  4. rhabdoviridae
  5. reoviridae
51
Q

RNA virus:

Picornaviridae

A
  • ssRNA, + strand, non-enveloped

- enterovirus, poliovirus, and rhinovirus (common cold)

52
Q

RNA virus:

Togaviridae

A
  • ssRNA, + strand, enveloped

- alphavirus, rubivirus

53
Q

RNA virus:

retroviridae

A
  • ssRNA, enveloped
  • lentivirus, oncoviruses
  • use reverse transcriptase to produce DNA from the viral genome
54
Q

in retroviruses, viral DNA integrates into the host chromosome as a

55
Q

RNA viruses:

Rhaboviridae

A

ssRNA, - sense, enveloped

-lyssavirus

56
Q

RNA viruses:

Reoviridae

A

dsRNA, non-enveloped

-reovirus, rotavirus

57
Q

sarcoma

A

cancer of connective tissue

58
Q

adenocarcinomas

A

cancers of the glandular epithelial tissue

59
Q

oncogenes

A

transform normal cells into cancerous cells

60
Q

oncogenic viruses

A

become integrated into the host cell’s DNA and induce tumors

61
Q

a transformed cell (tumor cell) harbors a:

A

tumor-specific transplant antigen (TSTA) on the surface or a T antigen in the nucleus

62
Q

DNA oncogenic viruses:

types of Herpesviridae

A
  • epstein-barr virus

- Burkitt’s lymphoma

63
Q

DNA oncogenic viruses:

types of papovarviridae

A

human papillomavirus (HPV)= cervical and anal cancer

64
Q

DNA oncogenic viruses:

types of hepadnaviridae

A

hepatitis B virus (HBV), role in liver cancer

65
Q

RNA oncogenic viruses

A

Retroviridae

  • human T cell leukemia viruses
  • HTLV-1 and HTLV-2 cause adult T cell leukemia and lymphoma

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