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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
list of tests for viral identification
- cytopathic effects - serological tests (i.e. Western Blotting) - nucleic acids (RFLPs, PCR)
26
western blotting viral identifcation
reaction of the virus with antibodies
27
overview of 2 cycles of bacteriophages
``` 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
list 5 steps of lytic cycle
1. attachment 2. penetration 3. biosynthesis 4. maturation 5. release
29
lytic cycle step 1: | attachment
phage attaches by the fibers to the host cell
30
lytic cycle step 2: | penetration
phage lysozyme breaks down the cell wall and injects its DNA
31
lytic cycle step 3: | biosynthesis
``` production of phage DNA and proteins eclipse period (virus is synthesizing viral components) ```
32
lytic cycle step 4: | maturation
assembly of phage particles
33
lytic cycle step 5: | release
phage lysozyme breaks the cell wall and host cell membrane lyses
34
lysogeny
phage remains latent
35
lysogenic cycle
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
results of lysogeny
immunity of lysogenic cells to reinfection by same phage
37
phage conversion
the host cell exhibits new properties | examples: corynebacterium diphtheria, clostridium botulinum
38
specialized transduction
specific bacterial genes transferred to another bacterium via a phage
39
animal viruses multiplication steps
- 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
location of biosynthesis steps in DNA viruses
- DNA viruses replicate their DNA in the nucleus of the host using viral enzymes - synthesize capsids in the cytoplasm using host cell enzymes
41
list of 5 examples of DNA viruses
1. adenoviridae 2. poxviridae 3. herpesviridae 4. papovaviridae 5. hepadnaviridae
42
DNA virus: | Adenoviridae
- dsDNA, non-enveloped | - common cold, acute respiratory infections, eye infections (viral conjunctivitis)
43
DNA virus: | Poxviridae
- dsDNA, enveloped | - poxviruses: smallpox, cowpox, skin lesions
44
DNA virus: | Herpesviridae
- dsDNA, enveloped - Simplexvirus - Varicellovirus - Lymphocryptovirus - cytomegalovirus - roseolovirus - rhadinovirus
45
DNA virus: | Papovaviridae
- dsDNA, non-enveloped | - papillomavirus
46
DNA virus: | Hepadnaviridae
- dsDNA, enveloped - hepatitis B virus - use reverse transcriptase to make DNA from RNA
47
in RNA virus biosynthesis, virus multiplies in the
host cell's cytoplasm using RNA-dependent RNA polymerase
48
ssRNA + strand
sense strand | -viral RNA serves as mRNA for protein synthesis
49
ssRNA - strand
antisense strand | -viral RNA is transcribed to a + strand to serve as mRNA for protein synthesis
50
list of 5 examples of RNA viruses
1. picornaviridae 2. togaviridae 3. retroviridae 4. rhabdoviridae 5. reoviridae
51
RNA virus: | Picornaviridae
- ssRNA, + strand, non-enveloped | - enterovirus, poliovirus, and rhinovirus (common cold)
52
RNA virus: | Togaviridae
- ssRNA, + strand, enveloped | - alphavirus, rubivirus
53
RNA virus: | retroviridae
- ssRNA, enveloped - lentivirus, oncoviruses - use reverse transcriptase to produce DNA from the viral genome
54
in retroviruses, viral DNA integrates into the host chromosome as a
provirus
55
RNA viruses: | Rhaboviridae
ssRNA, - sense, enveloped | -lyssavirus
56
RNA viruses: | Reoviridae
dsRNA, non-enveloped | -reovirus, rotavirus
57
sarcoma
cancer of connective tissue
58
adenocarcinomas
cancers of the glandular epithelial tissue
59
oncogenes
transform normal cells into cancerous cells
60
oncogenic viruses
become integrated into the host cell's DNA and induce tumors
61
a transformed cell (tumor cell) harbors a:
tumor-specific transplant antigen (TSTA) on the surface or a T antigen in the nucleus
62
DNA oncogenic viruses: | types of Herpesviridae
- epstein-barr virus | - Burkitt's lymphoma
63
DNA oncogenic viruses: | types of papovarviridae
human papillomavirus (HPV)= cervical and anal cancer
64
DNA oncogenic viruses: | types of hepadnaviridae
hepatitis B virus (HBV), role in liver cancer
65
RNA oncogenic viruses
Retroviridae - human T cell leukemia viruses - HTLV-1 and HTLV-2 cause adult T cell leukemia and lymphoma

ABS (31 decks)

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