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BIOL 4190- Final Exam Guide - Comprehensive Notes for the exam ( 32 pages long!)


Department
Biological Sciences
Course Code
BIOL 4190
Professor
R.Lu
Study Guide
Final

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LSU
BIOL 4190
FINAL EXAM
STUDY GUIDE

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Chapter 19. Influenza Virus
Describe the structural features of the influenza virus
Enveloped, (8) segmented (-) RNA circular/spherical genome (filamentous when
initially isolated, spherical after passing through cells)
Contains hemagglutinin (H) antigen glycoprotein spikes on the surface,
neuraminidase (N) antigen spikes, and M2 ion channel protein
16H + 9N = 144?
How does influenza virus enter the host cell?
Entry by endocytosis
Virus entry by endocytosis
H protein and Low-pH dependent membrane fusion
H protein must be cleaved by cellular proteases for the virus to be infectious
Which enzyme replicates the influenza virus and where does replication occur?
Transcription? Primer for transcription? Translation? Assembly?
Transcription complexes are initially released into the cytoplasm - then enter the
nucleus
Transcription occurs in nucleus, replication also occurs in the nucleus
Genome RNA has a 5’ cap
Transcripts have 5’ cap and 3’ polyadenylation
5’ cap of mRNA transcript has viral PB2 protein attached along with host mRNA
nucleotides - cap-snatching process
Viral PB2 snatches the host cap nucleotides - function as the primer for
transcription - host genome primer
Complex PA and PB1 dissociate from PB2 - create the poly-A tail of the
transcripts - viral genome polyadenylation
Replication and transcription creates (+) RNA from (-) RNA genome
Replication occurs using RdRP
Translation occurs in cytoplasm by ribosomes
Assembly occurs on inner cell surface of the golgi complex
Genome segments are packaged in virion
Can Tamiflu/oseltamivir be used to treat influenza virus infection?
Virions are released by budding - require N protein to be released because of
covalent bonds with viral H protein
Tamiflu and Relenza do not inhibit infection but they prevent release of viral
particles - treat infection
Symmetrel and flumadine prevent infection
Describe antigenic drift and antigenic shift
Antigenic drift is a gradual, seasonal shift in the strain
Variation within current genes
Antigenic shift is the reshuffling of genes between strains, creating a new virus
Acquisition of new genes - more severe/less common - cause of pandemic
strains
Chapter 20. Bacterial viruses
Is lysogeny a type of non-productive infection?
Yes, specifically a lysogenic infection, which is non-productive
Some temperate phages encode transposase which allows the bacteriophage to
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insert randomly into the chromosome
Other bacteriophages integrate into site specific locations within the chromosome
All bacteriophage gene expression is repressed by a repressor protein, which
confers superinfection immunity.
A resident prophage protect the host from superinfection by the same or
similar strains of phages by repressing the incoming phage genome.
Lysogenic conversionoccurs when a bacteriophage alters the phenotype of a
lysogenic bacterium
Streptococcus pyogenes and corynebacterium diphtheriae
Describe the structure feature and genome constitution of phage ϕX174, phage T7, Phi6
(ϕ6), phage MS2, and phage lambda
Phage X174
Icosahedral ssDNA
F protein - forms the main shell
G protein - forms the icosahedral spikes
H protein - pilot protein on the G spikes
The projections are involved in attachment to the host and delivery of the
genome into the host cell.
J protein: Highly positively charged DNA binding protein, associated
with genome
11 proteins encoded altogether through extensive use of overlapping genes
translated in alternative reading frames or employing different start
codons.
First entire DNA genome to be sequenced
All genes are transcribed in the same direction
Phage T7
A virulent T-odd phage, with linear dsDNA genome, icosahedral head,
short non-contractile tail
T7 early genes are transcribed by the bacterial RNA polymerase.
One of these early gene products is T7 RNA polymerase, a very active
enzyme that takes over transcription of T7 genes.
Late genes are transcribed from strong T7 promoters.
T7 RNA polymerase recognizes only T7 promoters.
Degradation of the bacterial chromosome during infection provides the
nucleotides for T7 replication, which uses T7 DNA polymerase.
All genes are divided into three groups and numbered from the genetic left
end, the first end to enter the host cell.
Phage Phi6
Segmented, enveloped dsRNA genome packaged in polyhedral inner
core
genome comprises three linear segments: RNA L (large), RNA M
(medium), and RNA S (small)
Uncoating occurs inside the cell and the polymerase, always carried by the
virus, is released.
Transcription of the double-stranded genome involves a phage RNA
dependent RNA polymerase. The plus strand transcripts serve as
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