Virology Midterm 1
Card Set Information
Virology Midterm 1
virology test midterm one
Midterm one questions.
What are some benefical roles of viruses?
gene therapy, phage therapy, vaccine develop
vaccines protect against?
disease, prevent cancer, pest control, phage therapy
which viruses are ancient?
chinese treated small pox with what technique?
aztecs exposed to which viruses?
smallpox and measels
when was small pox erradicated?
who invented smallpox vaccine?
When did jenner make pox vaccine?
when did who declare war on pox?
why did polio return?
sanitation, swers, age acquirement due to NO MATERNAL ANTIBODY
what are the stages of viral discovery?
discover virus, biochemical analysis, molecular analysis, recombinant tech.
1st virus to be imaged?
3 viral origin theories?
1. REgression 2. Modification 3. co-evolution
can have virus have both dna and rna?
speed of organism infections
ssDNA viruses common in:
ds dna common in bacteria animal viruses? t/f
Are all dsRNA viruses segmented?
yes and in animals.
mRNA has positive polarity if it's 5-3 t/f?
does negative DNA strand code for mRNA?
almost all dna viruses are dsDNA except
almost all RNA viruses are single stranded except
avg mw of a.a.?
avg mw of on base?
avg mw of base pair?
a protein subunit is one protein
a structural unit also called a protomer is 1 or more proteins t/f
morphological unit or capsomere was first observed by electron mic?
capsid is outter unit that what?
nucleocapsid is what?
capsid plus the genome
how many axis of symetrry for helical?
how many axis of symetry for icosahedral?
icosahedran has 20 faces and 12 vertices t/f
poxvirus has complex symmetry?
what are the three functions of viral particles?
1. protection 2. recognition 3. initiation
4 ways to classify a virus?
type of n.a., ss or ds?, envelope, symmetry
Plant virus common features:
RNA, non envelpoed, both symmetries
animal virus common features:
both rna and dna, both enveloped and non, both symmetries
common phage features:
dna, no envelope, more icosahedral then helical
DNA is mostly segmented in viruses?
most plant viruses have positive strand rna?
1 mRNA = 1 protein
if orf's are in a series are they in same reading frame?
what does 5' cap do?
facilitates synthesis of proteins, protectgs rna, splicining, transport nucleus
in viruses, what do the linked proteins at 5' end serve as?
what does a poly A tail do?
trna structure on virus genome purpose?
3 functional sequences purpose of virus genome?
1. transcribe for protein 2. translate for protein. 3. genome replicatoin
where are cis acting elements located?
3' and 5' non coding areas
where are trans acting elements located?
proteins ac on sequence to enhance replication at ends.
what does leader sequence do and contain?
ahead of start codon, in non coding areas. Contains ribosome binding site and enhancer sequence.
Instead of a 5' cap a virus will use a
where do promoters go for each strand type?
near 3' end for both positive RNA and negative RNA so as to get -RNA and positive RNA respectively. Can also go internal for subgenomic sequence.
Where is rna dependent rna polymerase found and for what?
negative rna viruses carry it with them to get the positive strand.
what are the strategies for multiple proteins in a limited viral genome?
frameshift, read through, polyprotein, subgenomic, multipartile genome
polyprotein products are cleaved with proteolytic action?
read through represented with a colon?
multipartile genome will have two genomic dna's?
where are the factors that control gene expression located?
upstream 5' end.
promoter consist of:
regaulatory sequence, initiatior sequence, TATA sequence
dsDNA promoter features:
promoter at 3' end, enhancer sequence, st and stop sequence
where does replication start in linear genomes?
characters of viral proteins?
structure, transmission, viral encoded enzymes with translational and transcriptional, enzymes to cleave proteins, primer for rna sequence VPG, cap enzymes, interfering proteins for immune dfense
protomers arranged as pentamer at vertex t/f
purpose of viral membrane proteins?
entry to cell, fusion to cell, antgenic sites, enzymatic activity
forms of viral membrane proteins?
matrix, glyco, external glyco, transport
how does virus get in gram positive bacteria?
target teichoic acid antigenic site
how does virus get in gram negative bacteria?
target lps O antigenic site
how does virus get in plant cell wall?
primary tissue culture
direct isolation from tissue
primary harvesting for individual cell types
transfer to keep density low
2 fold increase in population
die after fixed replications
do viruses grow exponentially?
can rickettesia or chlamydia grow on non living medium?
do enveloped viruses have to kill host?
can genome have nicks, supercoils or closed ends?
how may reading frames possible from one ORF?
which virus has wedge shape capsomere?
polio and rhinovirus
naked negative rna is infectious?
mrna from orf?
viruses in this family largest effector on humans
small pox, poxviradae
designation sequence for rna d. rna poly?
3' promoter with vpg
morphological units observed with electron mic?
rna genomes long or short generally?
where does polyermase bind? Ribosome?
promoter and ribosome binding site
purpose of UTR's?
contain regulatory sequences, enhancers, promoters etc.
what is a promoter?
reigion that initiates transcription of a gene.
direction that rna poly works?
5' to 3'
why particle weight not mw?