Chapter 6: Virus and Prions

At minimum, all viruses are composed of _______

Proteins Nucleic acids

Identify the commonalities between temperate phages and lytic phages.

Release Biosynthesis of viral components Penetration Assembly Adsorption

In some viruses, including HIV, the enzyme __________ ________ transcribes RNA into DNA.

Reverse Transcriptase

The sum total of the viruses associated with your body is called the ______.

Some viruses are in a dormant state in the body. The human virome includes viruses that infect our commensal bacteria.

Which process involves gene recombination via bacteriophage transfer?

Transduction

Which two of the following mechanisms are found to result in cancer caused by a virus?

Viral proteins cause changes in growth regulation, leading to cancer. The virus carries genes that can cause the cancer.

Which is most important for attachment of a virus to a host cell?

Viral specificity for host receptors

Identify the smallest pathogenic agent.

Virion

Which of the following is composed of only RNA?

Viroid

Which of the following statements regarding the membrane on an enveloped virus is true?

Viruses insert their own proteins in the membrane.

Which are the three main criteria used in classifying viruses into families?

b.) Genetic makeupd.) Structuree.) Chemical composition

The structure represented here as the protein subunit of a helical capsid is termed a ______.

capsomere

Viral nucleic acids are ______.

either single-stranded or double stranded

The 2 principle processes by which viruses penetrate host cells are ___________ (engulfment) and direct fusion.

endocytosis

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

envelope

In this image of an enveloped virus, the red arrow is pointing to the ______.

envelope

Which types of viruses are released by budding?

enveloped virus

Budding is a type of ______ process where enveloped viruses are released from the host cell membrane.

exocytic

______ viruses in the human body are pathogenic.

few

Viruses which have a series of rod-shaped capsomer proteins linked together forming a series of interconnected hollow discs are termed ______.

helical

Two shapes of viral capsids are ________, which resembles a bracelet; or __________, which is a type of polyhedron.

helical icosahedral

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

host

Viral transformation implies ______.

host DNA is changed

Which of the following is a term used to describe the different host cells which a virus can infect?

host range

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

induction

Typically, naked helical viruses are ______ flexible than enveloped helical viruses.

less

Hepatitis viruses have a tropism for cells of the ______.

liver

The process by which bacteriophages infect bacteria, conferring new traits enhancing human disease, is called ______.

lysogenic conversion

The cell component indicated by the arrow is a ______.

membrane receptor

The number of genes in a viral genome is _____ the number of genes in a bacterial genome.

much less than

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

naked; enveloped

_______ refers to the capsid and nucleic acid of a nonenveloped virus.

nucleocapsid

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

nucleus

Bacteriophages can infect which of the following?

prok. only

At minimum, viruses are composed of nucleic acid covered by a coating comprised of ______

protein

The chemical composition of the cell membrane structure indicated by the arrow is ______.

protein

Which macromolecule composes capsomeres?

protein

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

reverse transcriptase

Which of the following structures of enveloped viruses must be specific for adsorption?

spike proteins

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

spikes

What term is used to describe the viral proteins which protrude from the envelope and aid in attachment to host receptors?

spikes

The penetration step differs between animal viruses and bacteriophage in that ______.

the entire virus enters an animal cell, but only phage DNA enters a bacterial cell

A fully formed virus that is able to establish an infection in a host cell is often called a ______.

virion

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

viroid

A(n) is a microscopic, acellular agent composed of nucleic acid surrounded by a protein coat.

virus

Identify any of the following pathways which could produce proteins used by viruses.

1. Host DNA --> mRNA --> proteins used by viruses2. Viral positive-ssRNA --> proteins used by viruses

List the correct order of viral life cycle phases, starting with the first at the top.

1..adsorption 2.penetration/uncoating 3.synthesis 4.assembly 5.release

At a minimum, a viral genome must include genes for

-regulating the actions of the host cell-packaging the mature virus particles-synthesizing the viral capsid

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

Adsorption

is the viral process of attaching to the host cell receptor for the virus.

Adsorption

Identify the different environments in which some viruses can replicate.

Animal cells Bacterial cells Human cells

Identify prion related diseases.

Bovine spongiform encephalopathy Creutzfeldt-Jakob disease

Which structure immediately encloses viral nucleic acid?

Capsid

Identify all the components of the nucleocapsid.

Capsid Nucleic acid

Which of the following is the monomeric unit for a viral capsid?

Capsomere

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

Cytoplasm

Which term is used to describe the process when a virus is engulfed by a cell in a vacuole or vesicle?

Endocytosis

Identify all the methods that a virus can use to gain entry into an animal cell.

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

Which term is used to describe the phospholipid bilayer found surrounding the capsid of some viruses?

Envelope

True or false: The viral envelope and capsid are the same thing.

False Reason: The viral envelope is composed of phospholipids while the capsid is composed of capsomer proteins.

What are the viral spikes typically composed of?

Glycoproteins

Viruses which have symmetrical polygonal capsids are called ______.

Icosahedral

What is the term which describes a geometric viral form having 20 faces and 12 corners?

Icosahedrons

Which of the following best describes viruses?

Obligate intracellular parasites

Capsomeres are composed of _______. (Hint: it is a macromolecule)

PROTEIN

Which of the following best describe the relationship between viruses and their host cell?

Parasitism

Which of the following is used to describe the phage DNA that is latently incorporated into the bacterial host genome?

Prophage

Which term refers to the persistence of bacteriophages within host cells?

Lysogeny

Which four of the following are not found in viroids?

a.) Metabolic pathwaysc.) Mitochondriad.) Envelopee.) Capsid

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

capsid

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

capsid

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

capsomer

This helical capsid is comprised of protein subunits called _________

capsomer

Which of the following steps of the animal virus life cycle is not found in the bacteriophage life cycle?

the phage DNA is injected directly into the cell cytoplasm

A virus that only infects cells of a specific tissue in the body is described as having a ______.

tropism