Chapter 6: Virus and Prions
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
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
E. coli has about 4,000 genes in its chromosome. A virus that infects E. coli would be expected to have about ______ genes in its chromosome.
10
The smallest animal virus, parvovirus, is approximately what size?
20 nanometers
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 any of the following which can be used as primary cell lines.
Any of the answers listed here
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 term refers to the persistence of bacteriophages within host cells?
Lysogeny
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
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
What are viruses called which are capable of converting their RNA genomes into DNA?
Retroviruses
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.
Identify any benefits of viruses to people.
Some viruses control insect pests Some viruses can be modified to deliver genetic cures via gene therapy Some viruses control food pathogens
Which two of the following are cytopathic effects in virally infected animal cells?
Syncytia Inclusions
Which of the following is a multinucleated mass of cells due to the cytopathic effect of viral infection?
Syncytium
Which process involves gene recombination via bacteriophage transfer?
Transduction
True or false: Embryonic tissue can serve as a primary cell line for viral culture.
True
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 four of the following are not found in viroids?
a.) Metabolic pathwaysc.) Mitochondriad.) Envelopee.) Capsid
Which of the following describes the various viral parts coming together to produce virions?
assembly
Which are the three main criteria used in classifying viruses into families?
b.) Genetic makeupd.) Structuree.) Chemical composition
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
The structure represented here as the protein subunit of a helical capsid is termed a ______.
capsomere
Most bacteriophages contain which type of nucleic acid?
dsDNA
Identify all the types of nucleic acid genomes which have been discovered carried by various bacteriophages.
dsDNA ssRNA ssDNA
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
True or false: Bacteriophages infect eukaryotic and prokaryotic microorganisms.
false
______ viruses in the human body are pathogenic.
few
Which of the following term describes the total nucleic content of a virus?
genome
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
Primary cells undergo which type of division to produce a monolayer for animal virus culture?
mitotic
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
A virus that only infects cells of a specific tissue in the body is described as having a ______.
tropism
The process of ___________ occurs when viruses lose their envelope during penetration into a host cell or when the envelope/capsid is are dissolved within a vacuole.
uncoating
Which term describes the process of a virus losing its capsid and exposing viral nucleic acids to the immediate environment?
uncoating
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
Cytomegaloviruses, Epstein Barr viruses, bacteriophages, and the remainder of the approximately 1015 viruses associated with a typical adult can collectively be referred to as that individual's ______
virome
A(n) is a microscopic, acellular agent composed of nucleic acid surrounded by a protein coat.
virus
Cell (tissue) culture is considered an "in _____" (Latin phrase for "in glass") method to propagate virus.
vitro
When an enveloped virus buds off the cell membrane, the membrane differs ______ from the host cell's membrane.
significantly
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
__________phage is a bacteriophage that incorporates itself into the host genome as a lysogenic prophage. Correct Answer Blank 1: temperate
temperate
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
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
Cell culture and_______ culture have the same meaning.
tissue