Ch 13 Viruses Part 2 Flashcards
how do animal phages differ from bacteriophages
the mechanisms of entering the host cell are different as well as the synthesis and assembly of new viral components
what are the five stages of multiplication of animal viruses
1)attachment 2)entry 3)uncoating 4)biosynthesis 5)maturation/release
describe attachment in animal viruses
receptor sites are proteins and glycoproteins
receptor sites are inherited characteristics of the host
varies from person to person (susceptibility)
describe entry in animal viruses
receptor mediated endocytosis
fusion
this is how viruses enter eukaryotic cells
molecules bound to proteins on the plasma membrane are take in by infolding of the membrane
receptor mediated endocytosis
viral envelope fuses with the plasma membrane and releases the capsid into the cell’s cytoplasm
this is how enveloped viruses enter
fusion
describe uncoating in animal viruses
separation of the viral nucleic acid from its protein coat once the virion is enclosed within the vesicle
capsid is digested when the cell attempts to digest the vesicle’s contents
describe biosynthesis of DNA viruses
DNA containing viruses replicated DNA in nucleus of host by viral enzymes and synthesize capsid into cytoplasm with host enzymes
proteins then join with newly synthesized DNA to form virions (transported to ER)
what are the four steps of biosynthesis of DNA viruses
1) transcription then translation
2) synthesis of capsid proteins
3) maturation occurs in nucleus
4) complete virions are released
DNA virus
causes acute respiratory disease (common cold)
adenoviridae
DNA virus
skin leisons (pus filled)
small pox/cow pox
poxviridae
DNA virus
appearance of cold sores
HHV-1
herpeseviridae
DNA virus
warts, tumors, cytoplasmic vacuoles
capable of transforming cells/causing cancer
papovaviridae
DNA virus
cause hepatitis
hepadinaviridae
describe biosynthesis of RNA viruses
several different mechanisms of mRNA formation occur
RNA viruses multiply in the host cell’s cytoplasm
major difference lies in how much mRNA and viral RNA are produced
(once RNA is synthesized maturation is similar)
this is RNA within a virion that can act as mRNA
translated into two proteins which inhibit host synthesis of RNA (catalyze other strands of RNA)
sense strand or positive strand
template to produce additional positive strands
antisense strand or negative strand
single strand of RNA
contain RNA dependent RNA polymerase that uses negative strand as a template to produce positive strand
rhabdoviridae
respiratory and digestive systems of humans
viral mRNA is produced in the cytoplasm
reoviridae
enveloped viruses
single positive strand of RNA
two types of mRNA are transcribed from the negative strand
togaviridae
carry reverse transcriptase
provirus
retroviridae