chapter 16 viruses Flashcards
what is a virus
a small, infectious agent made of nucleic acid and protein
do viruses come in many shapes and sizes?
yes
capsid
protein coat
what do the proteins surrounding the virus do?
they are shaped to bind with proteins on host cells
each viruse has specific target cells that it can match up with to infect
host range
the types of cells or organisms a virus can infect
reservoir
the host that acts as a continual source of the viral infection for other host species
viral genes contain instructions for…
making viruses
how do viruses replicate?
by infecting host cells
5 stages of viral replication
attachment, penetration, synthesis, assembly, release
what happens during attachment
the virus attaches to host
what happens during penetration
the virus injects its nucleic acids into the cell
what happens during synthesis
host transcribes and translates viral DNA as if it were its own
what happens during assembly
new viruses assemble
what happens during release
viruses leave the cell
lytic pathway
viruses burst from their host cells soon after infection
lysogenic pathway
viruses that “hide” as they replicate, without damaging the host cell
prophage
the DNA of a lysogenic bacteriophage that is inserted into the host chromosome. the prophage replicates when cells divide
can viruses shift from lysogenic to lytic?
yes, depending on the condition of the host cell
when virally infected cells begin to die, do symptoms reflect the type of cells that are destroyed?
yes
virulent
describes the ability of a virus to damage its host during an infection
latent
viral genetic information inside an animal cell lies dormant
which is more complex, replication of DNA or RNA?
RNA
requires more steps
attachment and penetration for RNA viruses
produce a DNA copy of its RNA before incorporating genes into the host’s DNA
what enzyme converts RNA into DNA?
reverse transcriptase
