GCSU Microbiology Final (Bachoon) Exam |93 Q’s and A’s
definition of a virus - -a submicroscopic, parasitic, filterable agent consisting of a nucleic
acid surrounded by a protein coat
-which is smaller, viruses or bacteria? - -bacteria
-what can a virus infect? - --invertebrates
-vertebrates
-plants
-protists
-fungi
-bacteria
-when are viruses considered to be alive? - -ONLY when they are inside the host they
infect
-where do they multiply? - -inside living cells
-are viruses sensitive to antibiotics? - -NO
-what are viruses sensitive to? - -interferon
-host range - -- the spectrum of host cells a virus can infect
- most can only infect one specific host because it requires a specific site to attach to its
host
- those that infect bacteria are called "bacteriophage" or "phage"
-what 3 things makes up a virus? - -1) nucleic acid
2) capsid
3) envelope (on some viruses)
-1) nucleic acid - -- have DNA (or) RNA; not both
- double stranded or single stranded
- linear or circular
-genome size? - -ranges from a few thousand nucleotides to as many as 250,000
-2) capsid - -- protein coat surrounding and protecting the nucleic acid
-what is the capsid composed of? - -protein subunits called "capsomeres"
-3) envelope - -- on some viruses, it covers the capsid.
, - some envelopes may have "spikes" which are carbohydrate protein complexes that
project from the surface
-what is the envelope made up of? - -- lipids
- proteins
- carbohydrates
-what does the host immune system produce to the virus surface protein? - -antibodies
-what causes multiple infections by the same virus? - -in response to the immune system
producing antibodies to the virus surface protein, the virus can mutate these proteins at a
high rate causing multiple infections by the same virus
- ex: influenza virus
-what are the different morphologies of a virus - -- helical
- polyhedral
- enveloped
- complex
-helical viruses - -- long rods; may be rigid or flexible
- ex: causes rabies and ebola
-polyhedral viruses - -- icosahedron shape (20 triangular faces and 12 corners)
- ex: poliovirus
-enveloped viruses - -- capsid covered with an envelope
- roughly spherical
- ex: influenza virus, herpes virus
-complex viruses - -- complex shape
- these are bacteriophages when infecting bacteria
- ex: small pox or poxviruses
-taxonomy of viruses - -viral species will have same genetic information and same
ecological niche (host)
-in what 3 ways are viruses grown? - -1) in living animals
- ex: mice
2) in embryonated eggs
- ex: for vaccine products
3) in cell cultures (contained from cancer cells)
- ex: continuous cell lines or immortal cells,
-what two things contribute to the multiplication of a bacteriophage? - -1) the lytic cycle
(host cell dies)
definition of a virus - -a submicroscopic, parasitic, filterable agent consisting of a nucleic
acid surrounded by a protein coat
-which is smaller, viruses or bacteria? - -bacteria
-what can a virus infect? - --invertebrates
-vertebrates
-plants
-protists
-fungi
-bacteria
-when are viruses considered to be alive? - -ONLY when they are inside the host they
infect
-where do they multiply? - -inside living cells
-are viruses sensitive to antibiotics? - -NO
-what are viruses sensitive to? - -interferon
-host range - -- the spectrum of host cells a virus can infect
- most can only infect one specific host because it requires a specific site to attach to its
host
- those that infect bacteria are called "bacteriophage" or "phage"
-what 3 things makes up a virus? - -1) nucleic acid
2) capsid
3) envelope (on some viruses)
-1) nucleic acid - -- have DNA (or) RNA; not both
- double stranded or single stranded
- linear or circular
-genome size? - -ranges from a few thousand nucleotides to as many as 250,000
-2) capsid - -- protein coat surrounding and protecting the nucleic acid
-what is the capsid composed of? - -protein subunits called "capsomeres"
-3) envelope - -- on some viruses, it covers the capsid.
, - some envelopes may have "spikes" which are carbohydrate protein complexes that
project from the surface
-what is the envelope made up of? - -- lipids
- proteins
- carbohydrates
-what does the host immune system produce to the virus surface protein? - -antibodies
-what causes multiple infections by the same virus? - -in response to the immune system
producing antibodies to the virus surface protein, the virus can mutate these proteins at a
high rate causing multiple infections by the same virus
- ex: influenza virus
-what are the different morphologies of a virus - -- helical
- polyhedral
- enveloped
- complex
-helical viruses - -- long rods; may be rigid or flexible
- ex: causes rabies and ebola
-polyhedral viruses - -- icosahedron shape (20 triangular faces and 12 corners)
- ex: poliovirus
-enveloped viruses - -- capsid covered with an envelope
- roughly spherical
- ex: influenza virus, herpes virus
-complex viruses - -- complex shape
- these are bacteriophages when infecting bacteria
- ex: small pox or poxviruses
-taxonomy of viruses - -viral species will have same genetic information and same
ecological niche (host)
-in what 3 ways are viruses grown? - -1) in living animals
- ex: mice
2) in embryonated eggs
- ex: for vaccine products
3) in cell cultures (contained from cancer cells)
- ex: continuous cell lines or immortal cells,
-what two things contribute to the multiplication of a bacteriophage? - -1) the lytic cycle
(host cell dies)
