Ch. 16 Viruses

All viruses have a(n) ______, which is the protein coat that surrounds a virus.

capsid

Select all the conditions in a host cell that can cause bacteriophages to switch from the lysogenic pathway to the lytic pathway.

cell starvation DNA damage

Select all of the following that are true about the viral envelope.

contains embedded proteins composed of lipids derived from host cell membrane present in HIV

What symptom of influenza infection is due to dead and damaged host cells in the airway?

cough and sore throat

All viruses contain genetic material surrounded by a protein coat. In addition, some viruses have other features. Select all the features from the list below that some viruses have.

lipid-rich envelope enzymes

The outer envelope present in some viruses, such as the influenza virus and the human immunodeficiency virus (HIV), is composed of ______, which may be derived from the host cell's membrane.

lipids

During a(n) ______ viral infection, the genetic material of a bacteriophage is replicated along with the host cell's DNA, but the host cell is not immediately destroyed.

lysogenic

In what type of bacteriophage infection does the host cell burst open, releasing the new viral particles?

lytic

A viroid is

naked RNA that can infect plant cells.

Viruses are not part of the taxonomic hierarchy because

no single common ancestor has been identified by scientists.

The term prion is an abbreviation that stands for

proteinaceous infectious particle.

Vaccines work by causing

the immune system to recognize molecular components of the virus without the person having the disease.

During a lysogenic infection, some viral proteins respond to signals in the cell and trigger entry of the virus into ______, in which new viruses are assembled and the host cell is killed.

the lytic cycle

A latent viral infection is one in which

the viral genetic information remains inside the cell but does not cause disease symptoms.

The first virus ever discovered was ______, a virus that infects over 120 plant species.

tobacco mosaic virus

Select all of the organisms that tobacco mosaic virus can infect.

tomatoes tobacco peppers

The nucleic acids of viruses acquire mutations that can be passed on to new viruses inside a host cell.

true

Select the features that scientists use to classify viruses.

type of nucleic acid present type of disease caused type of replication viral structure

Preventative treatments for viruses called ______ cause the immune system to recognize molecular components of a virus without exposing the person to the disease, conferring future immunity to the target virus.

vaccines

A(n) ______ is a tightly wound circle of RNA without a protein coat that can infect a plant cell.

viroid

The ability of a virus to damage its host during an infection is termed

virulence

Although they do not have cell components such as cytoplasm or ribosomes, some ________ have enzymes and lipid-rich envelopes.

viruses

Most biologists do not consider _____ to be alive because they do not respond to stimuli and are unable to replicate on their own.

viruses

In a lysogenic infection, a ______ infects a host bacterium and ______.

bacteriophage; does not kill the cell

Viruses that infect bacteria are called

bacteriophages.

Rank the five steps of viral replication in the order in which they occur during an infection, beginning with the first step at the top.

1. attachment to host cell 2. penetration 3. synthesis of viral components 4. assembly of new viruses 5. release of new viruses form host cells

Match the reservoir animal on the left with the disease-causing virus it may carry. 1. wild birds 2. rodents 3. mosquitoes 4.raccoons

1. influenza 2. hantavirus pulmonary syndrome 3. yellow fever 4. rabies

All viruses contain genetic material, which is either RNA or ______, and a(n) ______ coat that surrounds the genetic material.

DNA; protein

Select all of the types of latent viruses that can lead to cancer because they persist by signaling the host cells to divide continuously.

Epstein-Barr virus human papillomavirus

How do abnormal prion proteins cause disease?

Masses of abnormal prions cause brain cells to die.

What structural feature of viroids helps prevent them from being degraded by host cell enzymes?

The RNA coils tightly into a double-stranded form.

What is one reason that most biologists do not consider viruses to be alive?

They cannot reproduce on their own.

Select all the reasons that viruses are not considered alive.

Viruses do not metabolize. Viruses do not respond to stimuli.

At the beginning of a viral infection, a virus attaches to a host cell by

adhering to a receptor molecule on the cell's surface.

Viruses can infect

all species.

Reservoirs for viruses that cause diseases in humans may be

animals

From the choices below, select the types of cells that can be infected with viruses.

bacteria fungi animals plants protists

Influenza viruses infect cells lining the airways of the respiratory system, and as a result ______ build up in the airways.

dead and damaged cells

The genetic material of different types of viruses is

either DNA or RNA.

Some viruses have an outer lipid-rich ______ that surrounds the protein coat.

envelope

A virus is an infectious agent that consists of

genetic information surrounded by a protein coat.

What features do all viruses have?

genetic material and a capsid

Select all of the following that occur during lysogenic infection of a bacterial cell.

genetic material of virus is replicated prophage may be formed

Select the two characteristics that all viruses share.

genetic material, either RNA or DNA a protein coat that surrounds the genetic material

The image shows ______, a virus that can cause latent and active infections in ______ of the immune system.

human immunodeficiency virus (HIV); T cells

In viruses with an envelope, proteins in the envelope help the virus

invade or attach to a new host cell.

Select all of the following that are true about the human immunodeficiency virus (HIV).

is an enveloped virus can cause latent infections contains the enzyme reverse transcriptase has an RNA genome

A virus that kills its host very quickly before spreading to other organisms

is highly virulent.

Select all the diseases that are caused by prions.

kuru "mad cow disease" Creutzfeldt-Jakob disease spongiform encephalopathies

A ______ infection of an animal virus does not produce disease symptoms or new viruses, but the viral information remains inside the cell.

latent