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