Microbiology Chapter 5

What are the phases of the viral life cycle in order?

-Adsorption -Penetration/Uncoating -Synthesis -Assembly -Release

What are the commonalities between temperate phages and lytic phages?

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

What methods can viruses use to gain entry into an animal cell?

-Fusion of the viral envelope and the cell membrane -Engulfment/phagocytosis of the virus

Treating viral diseases

-Most vaccines target viral diseases -Antibiotics are not effective against viruses

Which virus types are released from host cells by lysis?

-Naked -Complex

What are the componenets of the nucleocapsid?

-Nucleic acids -Capsid

Viruses can cause cancer by

-introducing oncogenes to a host cell -causing a loss of growth regulation

How are enveloped animal viruses released from the host cell?

-release from the ER -Bud off the cell membrane

What are the 3 main criteria used to classify viruses?

1. Structure 2. Chemical comp 3. Genetic makeup

3 purposes of viral cultivation

1. To study effects on host cells 2. To identify viruses in clinical specimens 3. To prepare vaccines

What is a Icosahedron?

A geometric viral form having 20 faces and 12 corners

When a cell harbors a virus that is not immediately lysing the cell, it is known as

A persistent infection

Prion

Abnormal protein fibrils

Which of the host cell structures must usually be specific for adsorption?

Glycoprotein receptors

Most host cell receptors that virus attach to are actually _____ that the cell uses in normal function.

Glycoproteins

What is a mass of viruses or damaged orgnalles caused by viral infection of a cell

Inclusion body

How does T-even bacteriophage nucleic acid enter the host cell?

Injection

Lysogeny is best described as

Integration of the viral genome into the host chromosome

Typically, naked helical viruses are _____ flexible than enveloped helical viruses. Less More

Less

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

Lysogenic conversion

_____ is the persistence of bacteriophage DNA within a host chromosome.

Lysogeny

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

Monolayer

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

Negative

At minimum all viruses are composed of

Nucleic acids and proteins

Most DNA viruses will assemble their virions within the host cell's...?

Nucleus

Where are most DNA viruses replicated and assembled within the host?

Nucleus

Viruses which can lead to cancer are called

Oncoviruses

What describes the "clear" area where a virus-infected cell lysed and infected all the neighboring cells and lysed those too.

Plaque

Virus is latin for

Poison

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

Prophage

Prions are composed entirely of what molecule?

Protein

Capsomers are composed of

Proteins

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

Provirus

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

Release

In some viruses, including HIV, what enzyme transcribes RNA into DNA?

Reverse transcriptase

A noncellular infectious agent that depends on other viruses for replication is known as what kind of virus?

Satellite Virus

Viral _____ insert into the host cell membrane as the virus particle is assembled in the host cell.

Spikes

Which disease is characterized by brain tissue pathology due to prions?

Spongiform encephalopathy

What is a multinucleated mass of cells caused by a viral infection?

Syncytium

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

Temperate phage

Virome

The complete set of viruses that can infect the human body

T or F: Bacteriophages can increase the pathogenicity of their bacterial host.

True

Change in a cell line monolayer is indicative of?

Virally infected cells

Is it possible for a bacterial cell infected with a temperate phage to replicate?

Yes

The monomer of a capsid is called

a capsomere

Endocytosis

a type of penetration, occurs when viruses are taken into the cell followed by englufment in a vacuole or vesicle

Viroid

an infectious agent that lacks a capsid and merely consists of a strand of RNA

Most RNA viruses will assemble the virion within the host cell's...?

cytoplasm

Host Range

defines that limitations of the type of cell that a virus can invade

A segmented RNA genome is one in which

individual genes exist on separate pieces of RNA

Through the process of _____, a prophage is activated and enters the lytic cycle

induction

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

obligate intracellular parasites

Syncytia

occur when a virus induces multiple cells to fuse, making a large multinucleated cell

Antiviral drugs target

one of the steps in the viral life cycle

The human virome is

the complete set of viruses that are associated with the human body

Which step in the life cycle of an animal virus is not needed in the life cycle of a bacteriophage?

uncoating

A fully formed infectious virus particle in a host cell is often called a

virion

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

virophage

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

Bacteriophage

Plaques are associated with

Bacteriophage infection of bacteria

Viruses ___ depend on a host cell for replication.

Completely

CPE

Cytopathic effect

Which of the following are cytopathic effects in virally infected animal cells? A. Viroids B. Virus-associated proteins C. Prions D. Inclusion Bodies E. Syncytia

D & E

Viral DNA polymerase genes are expressed during the _____ stage of the synthesis phase of the viral life cycle.

Early

A single virus particle could contain a genome consisting of

Either RNA or DNA, but NOT both

Viroids are composed of only...

naked RNA

Uncoating

is the process that occurs when viruses lose their capsid (and envelope if they have one) during or after penetration into a host cell

Both naked and complex viruses are released from host cells via

lysis

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

prophage

HIV is described as a _____ because it synthesizes DNA directly from RNA using reverse transcriptase

retrovirus

Most human viral infections are

self-limiting