Portage Learning BIOD 171 Module 6 With
Complete Solution
True .or .False: .viruses .can .be .classified .as .prokaryotic .or .eukaryotic .- .(correct
.answer) .-False. .Viruses .are .neither .prokaryotic .or .eukaryotic
What .is .an .obligate .intracellular .parasite? .- .(correct .answer) .-viruses .cannot .replicate
.unless .inside .a .living .host .cell. .As .a .parasite, .a .virus .depends .on .its .living .host .to
.provide .the .framework .(proteins, .etc) .to .replicate—to .make .additional .copies .of .itself.
What .is .a .viral .capsid? .- .(correct .answer) .-a .membrane-like .protective .structure .that
.contains .genetic .material .similar .to .nucleus .of .eukaryotic .cells.
What .is .the .viral .envelope, .and .what .does .the .presence .(or .absence) .of .it .tell .you
.about .the .type .of .virus? .- .(correct .answer) .-The .envelope .surrounds .the .viral .capsid,
.is .derived .from .the .host .cell .membrane .and .serves .as .an .additional .barrier .to .the
.external .environment. .The .overwhelming .majority .of .animal .viruses .are .enveloped
.whereas .the .majority .of .plant .or .bacteria-infecting .viruses .are .not.
What .type .of .microscope .would .be .used .to .study .the .shape .of .a .viral .capsid? .-
.(correct .answer) .-Due .to .its .size .(~30-150 .nm) .most .viral .capsids .must .be .visualized
.via .electron .microscopy.
How .does .the .viral .envelope .both .aid .in .cell .entry .as .well .as .hide .it .from .being
.detected .by .the .immune .system? .- .(correct .answer) .-The .viral .envelope .contains .the
.necessary .proteins .required .for .interaction .with .host .cells. .As .the .envelope .is .derived
.from .the .host .cell .membrane, .this .camouflages .the .virus .and .lowers .the .likelihood .of
.immune .detection .by .making .it .appear .similar .to .the .normal .biological .host .cell.
What .must .happen .before .viral .replication .of .its .genome .can .occur? .- .(correct
.answer) .-For .all .viruses, .the .genome .is .replicated .following .attachment .and .entry,
.never .before.
Describe .the .basic .steps .of .the .viral .life .cycle. .- .(correct .answer) .-1. .Attachment: .Viral
.receptors .bind .to .host .proteins .on .the .surface .of .the .cell.2. .Entry: .The .virus .fuses
.with .the .host .membrane .and .enters .the .cell3. .Uncoating: .(where .applicable) .the .viral
.capsid .disassembles4. .Replication: .The .viral .genome .provides .the .'blueprint' .to .make
.copies .of .itself5. .Exit: .New .viruses .are .produced .and .leave .the .cell6. .New .infection:
, .Newly .produced .viruses .leave .the .host .cell .and .go .on .to .infect .new .cells. .The
.process .outlined .above .now .restarts.
What .is .a .bacteriophage? .- .(correct .answer) .-A .virus .that .infects .bacteria
What .structural .aspects .make .bacteriophages .distinct .from .viruses .that .infect .either
.animals .or .plants? .- .(correct .answer) .-Bacteriophages .possess .an .icosahedral .capsid
.head .group .and .a .helical .tail. .Attached .to .the .tail .are .fibrous .extensions .or .'legs' .that
.aid .in .binding .host .cells. .Notably, .this .particular .structural .arrangement .has .not .been
.observed .among .viruses .that .infect .either .animals .or .plants.
Which .viral .replicative .process .results .in .the .destruction .of .the .host .cell? .- .(correct
.answer) .-The .lytic .replication .cycle .occurs .when .a .bacteriophage .replicates .within .a
.host .until .it .ruptures, .effectively .destroying .the .host .bacterial .cell. .The .phrase .lytic
.stems .from .'lysis', .meaning .to .rupture .or .disintegrate .(breakdown) .a .cell.
Describe .the .appearance .of .a .bacterial .culture .infected .with .virus .at .the .time .of
.infection .versus .later .once .viral .replication .is .occurring .at .a .high .rate. .- .(correct
.answer) .-During .the .initial .inoculation .of .virus .and .bacteria, .the .media .has .a .high
.degree .of .turbidity .(cloudiness). .However, .as .the .lytic .cycle .progresses .and .more .and
.more .bacterial .cells .are .destroyed, .the .culture .media .turns .from .turbid .to .clear, .as
.turbidity .is .a .function .of .the .number .of .intact .bacterial .cells .present .in .the .media.
.Thus, .as .bacterial .cell .numbers .decrease .due .to .lysis, .the .media .becomes .clearer.
To .what .family .of .viruses .does .rubella .come .from .and .how .is .it .transmitted? .-
.(correct .answer) .-Rubella .virus .belongs .to .a .family .of .viruses .called .Togaviridae.
.Rubella .is .transmitted .via .air-borne .particles .such .as .when .a .person .coughs.
What .is .the .common .name .for .rubeola, .and .is .it .a .DNA .or .RNA .virus? .- .(correct
.answer) .-Rubeola .is .commonly .referred .to .as .the .measles .and .belongs .to .the .family
.of .viruses .called .Paramyxovirus. .Rubeola .viruses .are .RNA .viruses .with .a .genome .~
.15,000 .nucleotides .long.
What .disease .state .emerges .as .a .viral .reactivation .of .a .prior .infection .with .the
.varicella .virus? .- .(correct .answer) .-Shingles, .also .known .as .Herpes .zoster, .is .due .to
.the .reactivation .of .the .varicella-zoster .virus .(VZV). .Because .VZV .lies .dormant .in
.inactive .nerve .cells, .its .reactivation .typically .results .in .painful .blisters. .However,
.unlike .the .initial .chickenpox .rash, .the .blisters .are .localized .and .limited .to .small .areas.
What .linear, .double-stranded, .enveloped .DNA .virus .is .the .first .virus .(as .of .October
.26, .1977) .to .be .declared .eradicated? .- .(correct .answer) .-Although .once .a .major
.cause .of .death .in .the .world, .a .smallpox .vaccine .was .developed .in .1796 .by .Edward
.Jenner. .Global .vaccination .efforts .have .prevented .smallpox .from .appearing .in
.humans .since .October .26, .1977, .making .smallpox .the .first .infectious .disease .ever .to
.be .eradicated.
Complete Solution
True .or .False: .viruses .can .be .classified .as .prokaryotic .or .eukaryotic .- .(correct
.answer) .-False. .Viruses .are .neither .prokaryotic .or .eukaryotic
What .is .an .obligate .intracellular .parasite? .- .(correct .answer) .-viruses .cannot .replicate
.unless .inside .a .living .host .cell. .As .a .parasite, .a .virus .depends .on .its .living .host .to
.provide .the .framework .(proteins, .etc) .to .replicate—to .make .additional .copies .of .itself.
What .is .a .viral .capsid? .- .(correct .answer) .-a .membrane-like .protective .structure .that
.contains .genetic .material .similar .to .nucleus .of .eukaryotic .cells.
What .is .the .viral .envelope, .and .what .does .the .presence .(or .absence) .of .it .tell .you
.about .the .type .of .virus? .- .(correct .answer) .-The .envelope .surrounds .the .viral .capsid,
.is .derived .from .the .host .cell .membrane .and .serves .as .an .additional .barrier .to .the
.external .environment. .The .overwhelming .majority .of .animal .viruses .are .enveloped
.whereas .the .majority .of .plant .or .bacteria-infecting .viruses .are .not.
What .type .of .microscope .would .be .used .to .study .the .shape .of .a .viral .capsid? .-
.(correct .answer) .-Due .to .its .size .(~30-150 .nm) .most .viral .capsids .must .be .visualized
.via .electron .microscopy.
How .does .the .viral .envelope .both .aid .in .cell .entry .as .well .as .hide .it .from .being
.detected .by .the .immune .system? .- .(correct .answer) .-The .viral .envelope .contains .the
.necessary .proteins .required .for .interaction .with .host .cells. .As .the .envelope .is .derived
.from .the .host .cell .membrane, .this .camouflages .the .virus .and .lowers .the .likelihood .of
.immune .detection .by .making .it .appear .similar .to .the .normal .biological .host .cell.
What .must .happen .before .viral .replication .of .its .genome .can .occur? .- .(correct
.answer) .-For .all .viruses, .the .genome .is .replicated .following .attachment .and .entry,
.never .before.
Describe .the .basic .steps .of .the .viral .life .cycle. .- .(correct .answer) .-1. .Attachment: .Viral
.receptors .bind .to .host .proteins .on .the .surface .of .the .cell.2. .Entry: .The .virus .fuses
.with .the .host .membrane .and .enters .the .cell3. .Uncoating: .(where .applicable) .the .viral
.capsid .disassembles4. .Replication: .The .viral .genome .provides .the .'blueprint' .to .make
.copies .of .itself5. .Exit: .New .viruses .are .produced .and .leave .the .cell6. .New .infection:
, .Newly .produced .viruses .leave .the .host .cell .and .go .on .to .infect .new .cells. .The
.process .outlined .above .now .restarts.
What .is .a .bacteriophage? .- .(correct .answer) .-A .virus .that .infects .bacteria
What .structural .aspects .make .bacteriophages .distinct .from .viruses .that .infect .either
.animals .or .plants? .- .(correct .answer) .-Bacteriophages .possess .an .icosahedral .capsid
.head .group .and .a .helical .tail. .Attached .to .the .tail .are .fibrous .extensions .or .'legs' .that
.aid .in .binding .host .cells. .Notably, .this .particular .structural .arrangement .has .not .been
.observed .among .viruses .that .infect .either .animals .or .plants.
Which .viral .replicative .process .results .in .the .destruction .of .the .host .cell? .- .(correct
.answer) .-The .lytic .replication .cycle .occurs .when .a .bacteriophage .replicates .within .a
.host .until .it .ruptures, .effectively .destroying .the .host .bacterial .cell. .The .phrase .lytic
.stems .from .'lysis', .meaning .to .rupture .or .disintegrate .(breakdown) .a .cell.
Describe .the .appearance .of .a .bacterial .culture .infected .with .virus .at .the .time .of
.infection .versus .later .once .viral .replication .is .occurring .at .a .high .rate. .- .(correct
.answer) .-During .the .initial .inoculation .of .virus .and .bacteria, .the .media .has .a .high
.degree .of .turbidity .(cloudiness). .However, .as .the .lytic .cycle .progresses .and .more .and
.more .bacterial .cells .are .destroyed, .the .culture .media .turns .from .turbid .to .clear, .as
.turbidity .is .a .function .of .the .number .of .intact .bacterial .cells .present .in .the .media.
.Thus, .as .bacterial .cell .numbers .decrease .due .to .lysis, .the .media .becomes .clearer.
To .what .family .of .viruses .does .rubella .come .from .and .how .is .it .transmitted? .-
.(correct .answer) .-Rubella .virus .belongs .to .a .family .of .viruses .called .Togaviridae.
.Rubella .is .transmitted .via .air-borne .particles .such .as .when .a .person .coughs.
What .is .the .common .name .for .rubeola, .and .is .it .a .DNA .or .RNA .virus? .- .(correct
.answer) .-Rubeola .is .commonly .referred .to .as .the .measles .and .belongs .to .the .family
.of .viruses .called .Paramyxovirus. .Rubeola .viruses .are .RNA .viruses .with .a .genome .~
.15,000 .nucleotides .long.
What .disease .state .emerges .as .a .viral .reactivation .of .a .prior .infection .with .the
.varicella .virus? .- .(correct .answer) .-Shingles, .also .known .as .Herpes .zoster, .is .due .to
.the .reactivation .of .the .varicella-zoster .virus .(VZV). .Because .VZV .lies .dormant .in
.inactive .nerve .cells, .its .reactivation .typically .results .in .painful .blisters. .However,
.unlike .the .initial .chickenpox .rash, .the .blisters .are .localized .and .limited .to .small .areas.
What .linear, .double-stranded, .enveloped .DNA .virus .is .the .first .virus .(as .of .October
.26, .1977) .to .be .declared .eradicated? .- .(correct .answer) .-Although .once .a .major
.cause .of .death .in .the .world, .a .smallpox .vaccine .was .developed .in .1796 .by .Edward
.Jenner. .Global .vaccination .efforts .have .prevented .smallpox .from .appearing .in
.humans .since .October .26, .1977, .making .smallpox .the .first .infectious .disease .ever .to
.be .eradicated.
