Basic Microbiology - Viruses

Lysogeny is best described as

integration of the viral genome into the host chromosome

Components of the nucleocapsid

nucleic acid and capsid

At minimum, all viruses are composed of

proteins and nucleic acids

Viral transformation by oncogenic viruses implies:

the host cell is changed

Lysogenic conversion is when

A bacterium acquires a new trait from its temperate phage

What is the correct term to describe viral adherence to a host cell receptor?

Adsorption

Which of the following is correct? A. All viruses have protein-synthesizing machinery B. All viruses lack the machinery to synthesize proteins C. Some virus can synthesize their own proteins

All viruses lack the machinery to synthesize proteins

Unlike organisms such as bacteria and protozoa, viruses

Are not cellular

During the _____ step in viral multiplication, capsids and genetic material are packaged into virus particles.

Assembly

What term is used to specifically describe the types of viruses that infect bacteria?

Bacteriophage

In what ways are enveloped animal viruses released from the host cell?

Bud off the cell membrane. Released from the endoplasmic reticulum.

The structure directly surrounding the viral nucleic acid is the _____, a coat of proteins.

Capsid

What is closest in physical proximity to the nucleic acid of a virus?

Capsid

This is considered a monomer (a single unit) of a capsid

Capsomer

A(n) _______ is a protein subunit that forms the viral capsid.

Capsomere

Which of the below would indicate that a virus is infecting a tissue culture cell line? A. Cells change color B. Cells degenerate and lyse C. Cells show no change

Cells degenerate and lyse

Viral nucleic acids are:

Either single-stranded or double stranded

The best method to visualize viruses is

Electron microscopy

What term is used to describe the process in which a virus is engulfed by a cell and enclosed in a vacuole or vesicle?

Endocytosis

Naked viruses do not possess a(n) _________

Envelope

A(n) _________ virus has a membranous layer external to the nucleocapsid.

Enveloped

List the order of viral life cycle phases.

1. Adsorption 2. Penetration/Uncoating 3. Synthesis 4. Assembly 5. Release

The interior of eggs normally contains non-pathogenic bacterial cells but no viruses.

False

Comparing viral and bacterial genomes, viruses have _______ genes.

Fewer

The total nucleic acid content of a virus can be referred to as the viral

Genome

The _____ range defines the limitations of the type of cell that a virus can invade.

Host

Some laboratory animals can propagate viruses in the laboratory more readily than others because many viruses exhibit

Host specificity

Viruses which have symmetrical 20 sided capsids are called ________

Icosahedral

Methods to study viruses that use living animals are called ________ methods, whereas methods that use tissue culture are called ________ methods.

In vivo; In vitro

Viruses are best described as _______ rather than "dead".

Inactive

A mass of viruses or damaged organelles caused by a viral infection of a cell

Inclusion body

A segmented RNA genome is one in which

Individual genes exist on separate pieces of RNA

What term is used to define the process of a prophage being activated and entering into the lytic cycle?

Induction

The term _____ is used to describe the physical rupture of a cell.

Lysis

__________ phages do not immediately lyse or change the appearance of host cells.

Lysogenic

A process of bacteriophage infection which could result in a new disease trait (such as a toxin) in the infected bacterium?

Lysogenic conversion

__________ phages enter the prophage state, while ________ phages burst the host cell.

Lysogenic; Lytic

Cultured cells grow in the form of a ___________, a single confluent sheet of cells that supports viral multiplication.

Monolayer

A _____ virus does not have an envelope surrounding its capsid.

Naked

Capsids of _______ helical viruses are rigid and tight, while capsids of _______ helical viruses are flexible and loose.

Naked; Enveloped

In _________-sense RNA viral genomes, the RNA is not in a form ready for translation.

Negative

All viruses must infect a host cell to replicate, and therefore, they are referred to as ________ intracellular parasites.

Obligate

Viruses that are ______ lead to cancer in infected hosts.

Oncogenic

Viruses which can lead to cancer are called

Oncoviruses

Viruses have tropisms, that is they can infect

Only cells of a certain tissue type

When a cell harbors a virus that is not immediately lysing the cell, it's known as what type of infection?

Persistent infection

A(n) _______ is observed as a clear area where virus-infected monolayers of cells have been disrupted or destroyed.

Plaque

Order the following microbes from smallest size to largest. Yeast cell, Polio virus, Streptococcus cell

Polio virus, Streptococcus cell, Yeast cell

Phage DNA that is latently incorporated into the bacterial host genome is called a

Prophage

Toxins of the bacteria responsible for diphtheria, cholera, and botulism are actually produced by:

Prophages

The viral spikes surrounding an enveloped virus are composed of

Protein

What macromolecule composes capsomers?

Proteins

A _______ is an animal virus which has integrated its DNA into the DNA of its host cell.

Provirus

A single virus particle could contain a genome consisting of

RNA only or DNA only

In which stage of viral multiplication would you expect to see "budding" occur?

Release

What are the commonalities between temperate phages and lytic phages?

Release, Adsorption, Penetration, Assembly, Biosynthesis of viral components

What are viruses called which are capable of converting their RNA genomes into DNA?

Retroviruses

An enzyme capable of taking an RNA genome and generating a DNA copy is called

Reverse transcriptase

What enzyme is found in HIV that is responsible for converting its RNA genome into a DNA genome?

Reverse transcriptase

Viral glycoproteins that protrude from the viral envelope and attach to host cell receptors are termed

Spikes

Which of the following is a multinucleated mass of cells caused by viral infection? A. Oncovirus B. Syncytium C. Inclusion body

Syncytium

What name is given to a phage "type" which can incorporate itself into the host genome as a lysogenic prophage?

Temperate

Which type of phage generally can increase the pathogenicity of a bacterium?

Temperate phage

What are some reasons that eggs provide an excellent in vivo viral cultivation system?

The interior environment of the egg is sterile. The egg is self-supporting.

Electron microscopy is the best method for visualizing viruses because

They are generally too small to be seen with a light microscope

Cell culture and _____ culture have the same meaning.

Tissue

Positive-sense RNA is RNA that can be immediately

Translated into protein

Viruses are not cellular.

True

The process of _________ occurs when viruses lose their capsid (and envelope, if they have one) during or after penetration into a host cell.

Uncoating

Virus cultivation is an important activity because viral stocks are needed for the preparation of some

Vaccines

A fully formed infectious virus in a host cell is referred to as a

Virion

A(n) ______ is an infectious agent that lacks a capsid and merely consists of a strand of RNA.

Viroid

Which of the following is composed of only RNA?

Viroid

A type of virus that parasitizes other viruses infecting the same host cell is called a

Virophage

Embryonic eggs:

are completely sterile

Plaques are associated with what?

bacteriophage infection of bacteria

What are in vivo methods for viral cultivation?

Inoculating chicken eggs with viruses. Inoculating mice with viruses.