UVA BIO 2100 - Exam 5 Questions With Complete
Solutions
Describe what RNA-interference is, ways in which microRNAs
(miRNA) can silence gene expression, and a natural role of
miRNA
RNA-interference - double stranded RNAs that will destroy the
target sequence, act in catalytic manner, one microRNA can
target and block the expression of many, either will cut up RNA
segment or block its translation, forms RNA induced silencing
complex with proteins which when induced can either degrade
mRNA or block translation, viruses use this, when mRNA is
transcribed, microRNAs will block translation if the specific
protein isn't needed
• Describe characteristics common to all viruses & common
variations in structure and genome
capsid - outer wrapper, contains nucleic acid, targets host cells
some are enveloped have outer membrane surrounding capsid,
fuses with the host cell membrane during endocytosis
all make of nucleic acids and have no metabolic functions
not considered living, need a host to survive
some have dsDNA, ssDNA, ssRNA and some of the RNA in the
genome is + while some is - and has to be copied before it can
served directly as mRNA
many contain proteins structural - capsid, spikes and
nonstructural - proteases and RDRP
most invade host, copy their nucleic acid, make new genomes
,and new capsids and then exit cell
cause cell death leading to disease
Describe why most biologists don't consider viruses to be living
only living characteristic is order, cannot synthesize or divide
without a host, obligate intracellular parasites, can be
inactivated, no synthesis or metabolism on their own
Describe a typical replication cycle of an animal virus and
explain why viruses typically replicate and cause disease in only
certain species and replicate in only certain cell types
tropism - only certain cells affected, and only certain species
bind to the hosts cell receptor, enter the cell through endocytosis
and the envelope combines with plasma membrane, use host
ribosome to form rdrp complex and replicated the RNA/DNA
and use it to form new capsid protein shells and copies of the
viral genome, also contain non structural proteins which inhibit
protein synthesis and other functions of the host causing disease
and then death, once replicated they leave cell to infect others
• Describe common mechanisms of viral pathogenesis
endocytosis into host cell, genome enters host cell, uses
ribosome from host to make copies, polypeptide is cleaved by
protease and then makes complex of replicase with RDRP a
replication transcription complex using the enzyme RDRP
which synthesizes RNA from RNA, then continue to make
antisense and sense strands which are translated into capsid
proteins and more copies of genome, use nsp to inhibit normal
functions of the host cell causing death
, Explain why antibiotics don't affect viruses, but examples of
how antiviral agents can
antibiotics target bacteria which are living organisms, slow
down their growth and spread, attack the cell walls of bacteria,
bacteria are on outside of cells
viruses don't have cell walls, viruses also move inside of the
cells, antivirals can work by inhibiting the RNA synthesis by
RDRP, remdesivir is a delayed chain terminating nucleotide
analog which targets synthesis by the RDRP, AZT can be used
which targets reverse transcription, some target the attachment
site and inhibit attachment
Interpret data from "time-of-addition" studies to identify
potential targets of antiviral drugs
testing compounds to determine when they appear to be
effective to see what part of the viral replication process they
prevent, look at charts and when the viral level goes back up is
when they stopped working
Explain why biologists exploit engineered viruses for
therapeutic use
Describe what a (conventional) transgenic organism is, reasons
why they are made, and why breeding is required to produce a
"true-breeding" colony of transgenic animals, and how
transgenic organisms fundamentally differ from gene therapy
recipients
transgenic organism is adding a gene to another organism,
deliberately introducing a gene, this can determine info about
Solutions
Describe what RNA-interference is, ways in which microRNAs
(miRNA) can silence gene expression, and a natural role of
miRNA
RNA-interference - double stranded RNAs that will destroy the
target sequence, act in catalytic manner, one microRNA can
target and block the expression of many, either will cut up RNA
segment or block its translation, forms RNA induced silencing
complex with proteins which when induced can either degrade
mRNA or block translation, viruses use this, when mRNA is
transcribed, microRNAs will block translation if the specific
protein isn't needed
• Describe characteristics common to all viruses & common
variations in structure and genome
capsid - outer wrapper, contains nucleic acid, targets host cells
some are enveloped have outer membrane surrounding capsid,
fuses with the host cell membrane during endocytosis
all make of nucleic acids and have no metabolic functions
not considered living, need a host to survive
some have dsDNA, ssDNA, ssRNA and some of the RNA in the
genome is + while some is - and has to be copied before it can
served directly as mRNA
many contain proteins structural - capsid, spikes and
nonstructural - proteases and RDRP
most invade host, copy their nucleic acid, make new genomes
,and new capsids and then exit cell
cause cell death leading to disease
Describe why most biologists don't consider viruses to be living
only living characteristic is order, cannot synthesize or divide
without a host, obligate intracellular parasites, can be
inactivated, no synthesis or metabolism on their own
Describe a typical replication cycle of an animal virus and
explain why viruses typically replicate and cause disease in only
certain species and replicate in only certain cell types
tropism - only certain cells affected, and only certain species
bind to the hosts cell receptor, enter the cell through endocytosis
and the envelope combines with plasma membrane, use host
ribosome to form rdrp complex and replicated the RNA/DNA
and use it to form new capsid protein shells and copies of the
viral genome, also contain non structural proteins which inhibit
protein synthesis and other functions of the host causing disease
and then death, once replicated they leave cell to infect others
• Describe common mechanisms of viral pathogenesis
endocytosis into host cell, genome enters host cell, uses
ribosome from host to make copies, polypeptide is cleaved by
protease and then makes complex of replicase with RDRP a
replication transcription complex using the enzyme RDRP
which synthesizes RNA from RNA, then continue to make
antisense and sense strands which are translated into capsid
proteins and more copies of genome, use nsp to inhibit normal
functions of the host cell causing death
, Explain why antibiotics don't affect viruses, but examples of
how antiviral agents can
antibiotics target bacteria which are living organisms, slow
down their growth and spread, attack the cell walls of bacteria,
bacteria are on outside of cells
viruses don't have cell walls, viruses also move inside of the
cells, antivirals can work by inhibiting the RNA synthesis by
RDRP, remdesivir is a delayed chain terminating nucleotide
analog which targets synthesis by the RDRP, AZT can be used
which targets reverse transcription, some target the attachment
site and inhibit attachment
Interpret data from "time-of-addition" studies to identify
potential targets of antiviral drugs
testing compounds to determine when they appear to be
effective to see what part of the viral replication process they
prevent, look at charts and when the viral level goes back up is
when they stopped working
Explain why biologists exploit engineered viruses for
therapeutic use
Describe what a (conventional) transgenic organism is, reasons
why they are made, and why breeding is required to produce a
"true-breeding" colony of transgenic animals, and how
transgenic organisms fundamentally differ from gene therapy
recipients
transgenic organism is adding a gene to another organism,
deliberately introducing a gene, this can determine info about
