chapter 5 practice questions

prophages are

- Present when the virus is in lysogeny - Formed when viral DNA enters the bacterial chromosome - Replicated with host DNA and passed on to progeny - Occur when temperate phages enter host cells

All of the following pertain to virus envelopes

- gained as a virus leaves the host cell membrane - are comprised primarily of lipids - contain special virus proteins - help the virus particle attach to host cell

Uncoating of viral nucleic acid ________.

-does not occur in bacteriophage multiplication. -involves enzymatic destruction of the capsid. -releases viral nucleic acid into the cell -occurs before replication.

viruses

Cannot be seen in a light microscope

Reverse transcriptase synthesizes ________.

DNA from RNA

Which of the following is not true regarding the structure and function of viral spikes?

They are coded for by the host genome

Which of the following statements best explains how a bacteriophage can impair human health?

Toxins or enzymes are produced by the infected bacterial pathogen that cause pathology in humans.

Even though it is a bacterium, Clostridium botulinum can be made more pathogenic once infected with a(n) _____.

bacteriophage

A(n) _______ is the protein shell around the nucleic acid core of a virus

capsid

Helical and icosahedral are terms used to describe the shapes of a virus _____.

capsid

Viruses contain the necessary tools to invade and control a host cell. These tools may consist of a ________.

capsid or envelope, nucleic acid strands of DNA or RNA, and enzymes

Virus capsids are made from subunits called _

capsomeres

A common method for cultivating viruses in the lab is to use in vitro systems called _____ cultures.

cell

Viral genetic studies, vaccine development and clinical identification would not be possible without the ability to ________.

culture viruses in vivo and in vitro

A patient undergoing chemotherapy for cancer develops an infection with cytomegalovirus, conclusively diagnosed by the presence of "owl's eye" viral nuclear inclusions in a liver biopsy. This is an example of a(n) ________.

cytopathic effect by cytomegalovirus

Viruses have all the following

definite shape, genes, ability to infect host cells, ultramicroscopic size

Satellite viruses are ________.

dependent on other viruses for replication

An ideal antiviral drug would be one that ________.

disrupted an integral viral process while causing little damage to the host cell

The core of every virus particle always contains _____.

either DNA or RNA

The viral genome is carried by _____.

either DNA or RNA but not both

A specific animal virus has the ability to attach to and enter almost any animal host cell.

false

Glycoprotein spikes are essential for mediating the release stage of the viral life cycle

false

The adeno-associated virus (AAV) is a prion

false

Viruses are not filterable

false

Viruses are ultramicroscopic because they range in size from 2 mm to 450 mm.

false

Oncoviruses include all the following

hepatitis B, papillomavirus, HTLV 1, epstein barr virus

During lysogeny, an inactive prophage state occurs when the viral DNA is inserted into the ________

host DNA

Viruses attach to their hosts via ________.

host glycoproteins

Host cells of viruses include ________.

humans and animals, plants and fungi, bacteria, protozoa, and algae

The activation of a prophage is called _____.

induction

T-even phages ________

infect Escherichia coli cells

The event that occurs in bacteriophage multiplication that does not occur in animal virus replication is ________

injection of only the viral nucleic acid into the host cell

The envelope of enveloped viruses ________.

is obtained by viral budding or exocytosis

Respiratory syncytial virus (RSV) is a common respiratory virus that causes mild cold-like symptoms in most individuals, but can be more serious in infants and the elderly. RSV is so-named because ________.

it causes the fusion of damaged host cells, forming a large, multinucleated cell

New, nonenveloped virus release occurs by _____.

lysis

When a bacterium acquires a trait from its temperate phage, it is called

lysogenic conversion

Cells grown in culture form a(n)

monolayer

A negative-sense RNA virus ________.

must synthesize a positive RNA copy of its genome

A naked virus has only a(n) _____.

nucleocapsid

In general, most DNA viruses multiply in the host cell's _______, while most RNA viruses multiply in the host cell's _______.

nucleus; cytoplasm

Who developed a rabies vaccine by separating bacteria from virus using a filter

pasteur

Visible, clear, well-defined patches in a monolayer of virus-infected cells in a culture are called

plaques

Viruses with _______ -sense RNA contain the correct message for translation, while viruses with _______ -sense RNA must first be converted into a correct message

positive;negative

Infectious protein particles are called _____.

prions

Two noncellular agents, smaller than viruses, are the infectious proteins called _______ and the infectious RNA strands called ________.

prions; viroids

viral spikes ______

protrude from the envelope.

Viruses acquire envelopes around their nucleocapsids during _____

release

What structures are used by bacteriophages to attach to host cell receptors?

tail fibers

What type of phage enters an inactive prophage stage?

temperate

You are running an experiment in calf serum, which cannot be autoclaved because proteins essential to your protocol will be denatured. You decide to filter sterilize the serum since the 0.22μm filter is small enough to block any bacteria that may contaminate your tissue culture. The success of this procedure hinges on the fact that ________.

the presence of viruses in your serum is inconsequential to your experiment

Viral tissue specificities are called _____

tropisms

A fully formed virus that can cause an infection in a host cell is called a virion.

true

Prophages can be activated into viral replication and enter the lytic cycle

true

Spikes are glycoproteins of the virus capsid

true

Viral spikes are inserted into the host cell membrane before budding or exocytosis

true

Viruses are simple, noncellular, and lack ribosomes

true

Viruses are the most common cause of acute infections that do not result in hospitalization

true

Viruses are unable to multiply outside of a host cell

true

Viruses mutate and some have not been discovered

true

When a virus enters a host cell, the viral genes redirect the genetic and metabolic activities of the host cell.

true

Host range is limited by ________.

type of host cell receptors on cell membrane

The process of dissolving the envelope and capsid to release the viral nucleic acid is ____

uncoating

Lysogeny refers to ________.

viral genome inserting into bacterial host chromosome

Infectious naked strands of RNA that affect plants are called _____.

viroids

The development of antiviral drug therapy is difficult because ________.

viruses are obligate intracellular parasites so the host cell can be harmed by the drug

Which of the following occurs during assembly of an enveloped virus

a nucleocapsid is formed and viral spikes insert in host cell membrane.