13.6 animal virus replication
reverse transcriptase:
-enzyme for encoding reverse-transcribing viruses -an RNA dependent DNA polymerase, which synthesizes DNA from an RNA template.
the mechanism of entry for an animal virus is primarily determined by whether or not the virus has ___?___ (structure)
envelope
enveloped viruses acquire their outer covering in:
from the host cytoplasmic membrane
replication of RNA viruses:
-RNA viruses are single-stranded -replicate in cytoplasm -replication req. a virally encoded RNA polymerase called REPLICASE
which of the following viral or bacteriophages release methods may not initially destroy the cell?
-budding
non-enveloped virus can gain entry into animal cells via:
-endocytosis of the virus by the host cell
what are the molecules (receptors) that viral spikes attach to on the host cell typically composed of?
-glycoproteins
uncoating
after a virus enters a cell, the nucleic acid separates from the protein coat.
viruses:
-some req. more than one host receptor for attachment -viruses use their spikes to attach to host cell receptors -blocking a host receptor with a drug would prevent a virus from infecting that cell
enveloped viruses can derive (obtain)their envelopes from:
-the host cytoplasmic membrane -certain host organelles (golgi apparatus/ rough e.r)
what is required for production of virus particles in a host cell:
-translation of viral genes -replication of viral genome -transcription of viral genes
which is most important for attachment of a virus to a host cell?
-viral specificity for host receptors
viruses can be divided into 3 groups based on their replication strategies:
1. DNA viruses 2.RNA viruses 3. reverse transcribing viruses
enveloped virus can gain entry into animal cells by:
1. endocytosis of the virus by the host cell 2.fusion of the viral envelope and the cell membrane.
during the ___?___ step in viral multiplication, capsids and genetic material are packaged into virions.
assembly step
non-enveloped viruses mature fully in the :
host cell cytoplasm
replicase:
is an RNA-dependent RNA polymerase (meaning that it is able to synthesize a strand of RNA from an RNA template.
apoptosis:
is used to describe programmed cell death, a process naked viruses sometimes trigger as a means of release.
most animal DNA viruses will replicate within the host cell's...
nucleus
antigenic shift:
occurs when 2 different strains of a segmented virus enter the same cell, reassortment of the gene segments can occur, resulting in antigenic shift
RNA viruses have a higher mutation rate than DNA viruses because replicase lacks ?
proofreading ability
HIV is described as an ___?___ because it replicates its RNA genome by using reverse transcriptase to produce a DNA intermediate
retrovirus
one symptom of a respiratory virus infection is coughing and sneezing. this allows:
viral particles to be shed from one host and transmitted to a new host