L25 Flashcards
viruses are _ _ _ - rely
on host _ _ to reproduce
obligate intracellular parasites
biosynthetic machinery
(virions)
when not inside an infected
cell, viruses exist as
independent particles
Simplest viruses encode_
proteins.
Most encode _ proteins
compared to humans (_)
4
100-200
~20 000)
virions consist of (3)
double or single stranded DNA
or RNA
• a protein coat (capsid)
• lipid envelope
lipid
envelope
derived from the host
cell which, like the capsid, may
contain antigenic glycoproteins
virion size
~1/100th the size of the average
bacterium
•Viral range
group of cell types
(or species) that a virus can infect.
bacteriophage.
•Virus that infects only bacteria
animal viruses or plant
viruses.
•Viruses that infect animals or plants
•Most animal viruses to do not cross _, and some only infect closely related _ (ie humans and primates for poliovirus)
•Most animal viruses to do not cross phyla, and some only infect closely related species (ie humans and primates for poliovirus)
•Viruses can be classified based on the shape of their
capsid
capsid shapes
(helical, icosahedral, complex)
pathogenicity
Ability of viruses to cause disease
virulence.
• degree of pathogenicity
latency.
Some viruses can remain dormant in organisms
eg of latent viruses
varicella zoster (chicken pox, shingles)
carriers
• People chronically infected are called carriers and serve as reservoirs of infectious virus
“Life” cycle of viral replication:
absorption,
penetration, replication, release
Surface of viruses have __ that bind to receptor protein on host cell. _ determines the _ range of a virus and begins the infection process (i.e. HIV and
CD4).
Viral _ or _ crosses the plasma membrane to the cytoplasm or nucleus
Once inside, viral DNA or RNA interacts with host _ _ _ DNA or RNA into viral protein
newly synthesized _ particles are released to continue infection cycle
Surface of viruses have proteins that bind
to receptor protein on host cell. Interaction
determines the host range of a virus and
begins the infection process (i.e. HIV and
CD4).
Viral DNA or RNA crosses the plasma
membrane to the cytoplasm or nucleus
Once inside, viral DNA or RNA interacts
with host machinery for translating DNA or
RNA into viral protein
newly synthesized virion particles are
released to continue infection cycle
