Chapter 13: Viruses, Viroids, Prions Flashcards
Virus that infects bacteria, often called a phage. This is its real name
Bacteriophage
Infection in which the viral genome is present in the host cell but not active
No new particles being produced
Latent infection
A bacterium that carries phage DNA (prophage) integrated into its genome
Lysogen
A change in 1 or more of the properties of a bacterium upon acquiring a prophage
Lysogenic Conversion
A productive infection that causes the host cell to burst (lysis)
Lytic infection
Infectious protein that causes neurodegenerative disease
Prion
Viral infection in which more viral particles are produced
Productive infection
Infectious agent of plants that consist only of RNA
Viroid
Complete virus in its inert non-replicating form outside a host cell; also referred to as a viral particle
Virion
The genome in virus maybe linear or circular
Single or double stranded
T or F
T
Protein coat that surronds the nucleic acid of a virus
Capsid
Protein units that form a capsid are called
Capsomeres
Viral nucleic acid and its protein coat(caspid) are called
Nucleocapsid
Structures on the outside of the virion that bind to host cell receptors
Spikes
Some viruses have an outer lipid bilayer called an envelope, others don’t.
Does this make them more or less susceptible to soaps and other disinfectants.
Why
More susceptible
The chemicals bind to the lipid layer removing the spikes
Phages are typically enveloped or non-enveloped
Non-enveloped
Non-enveloped viruses consist of (name the parts)
Capsomere
Nucleocaspid (nucleic acid and caspid)
Spikes
Enveloped viruses consist of (name parts)
Spikes
Matrix protein
Nucleocaspid (Nucleic acid & caspid)
Envelope
3 shapes of viruses. Describe shape
Icosahedral
Helical
Complex
Icosahedral: Soccer ball like
Helical: spiral stair case
Complex: Mixture of the two. Tradional Virus shape
What is analogous to Domain in Viruses
Realm
What does the suffix-viridae mean
virus
Are virus names capitalized or italicized
No
Arhtropod-borne RNA virus, carried by vectors such as mosquitoes
Arbovirus
Entric viruses come from what
Feces. Named after “entero” system or intestines
Almost all ______ are Non-enveloped, whereas animal viruses can be either enveloped or not
Bacteriophages
Viruses are classified based primarily on characteristics of their genome type such as….
Nucleic acid and strandedness
Viruses are group by…
Their route of transmission
The state of a phage when it’s DNA is integrated into the genome of the host
Latent state
Bacteriophages that lyse their host are called (2)
Lytic phage / virulent phage
How do phages make Genome entry
Using lysozyme
Synthesis of phage protein and genome happens by the phage. One of the first protiens transcribed is ______ which degrades the host cells DNA
Nuclease
How are phages released from the cell after they have been synthesized
Lysozyme lysis the cell from the inside out
A bacteriophage that can either direct a productive infection that leads to the host cell lysis
Or
Remain silent within the host as a prophage that replicates along with the host cell genome
Is this type of phage
Temperate phage
Latent form of a temperate phage; the phage DNA has generally been inserted into the host’s chromesome
Prophage
Bacterium that carries phage DNA(prophage) integrated into its genome
Lysogen
Temperate phages have two options to spread phages inside their host
Lytic infection
Lysogenic infection
Describe both
Lytic: subsequent production of more viral particles and lysis of the cell
Lysogenic infection: Phage DNA replicates silently as a prophage (integrated into host chromesomes) eventually they get triggered to be excised from the host’s DNA and form viral particles and lysis the cell
Process by which phage DNA is excised from bacterial chromosomal DNA
Phage induction
Which process can Excise phage DNA from the chromesome
SOS repair
The change in phenotype of a lysogen as a result of the specific prophage it carries
Lysogenic conversion
Change in the properties of a bacterium, conferred by a prophage
Lysogenic conversion
Temperate phages either lyse their host or exist within the host as a….
Prophage
Filamentous single-stranded DNA phages are ______ from the host cell without killing the cell
Extruded
_____ results from packaging errors during phage assembly
Generalized transduction
Bacterial progeny that contains a Bacterial genome instead of phage DNA due to an error during packaging
Transducing particle
_____ results from an excision mistake made by a temperate phage during its transition from lysogenic to a lytic cycle
Specialized transduction
Which Transduction involves the transfer of both bacterial and phage DNA
Specialized transduction
Method used to measure the number of viral particles present in a sample
Plaque assay
Circular zones of clearing in the bacterial lawn
Plaques
5 steps of infection cycle of animal virus
Attachment
Genome entry
Synthesis
Assembly
Release
How does virion entry differ from phages
Virions enter fully into the cell
Phages only inject nucleic acid
Enveloped viruses enter the host 2 ways.
Fusion with the host membrane
Endocytosis
3 types of replication of DNA viruses
Double stranded: Similar to DNA replication Central Dogma
Single-Stranded DNA: A complement to the single strand must be made
Retoviruses: 2 copies of single stranded RNA and reverse transcriptase, Converted to double stranded DNA. Integrated into chromesome as a PROVIRUS. This part is transcribed to make a Polyprotein which is then cleaved to produce the parts of the virion
2 copies of single stranded RNA and reverse transcriptase, Converted to double stranded DNA. Integrated into chromesome as a PROVIRUS. This part is transcribed to make a Polyprotein which is then cleaved to produce the parts of the virion
Describes this process
Retoviruses duplication
Minor changes that occur naturally in influenza virus antigens as a result of mutations
Antigenic drift
Segmented viruses do what
Their genomes consist of more than 1 piece of RNA.
If 2 strains infect the same cell they can reassort and produce new types
Antigenic shift
Major changes in the antigenic composition of flu viruses that result from reassortment of viral RNA during infection of the same host cell by different strains
Antigenetic shift
Reverse transcriptase does what?
Synthesizes DNA from RNA
Group of viruses that have a single-stranded RNA genome; their enzyme reverse transcriptase synthesizes a DNA copy that is then integrated into the host’s cell chromesome
Retrovirus
Viral assembly involves packaging the ____ into the _____
Nucleic acid/ capsid
Most enveloped viruses are relased from the host cell via
Budding
Non-enveloped viruses are relased from…
Apoptosis
Animal viruses can be divided into 2 categories
Acute
Persistent
Persistent viruses can be divided into
Chronic & Latent
Latent form of a virus in which viral DNA is incorporated into the chromesome of the host
Provirus
Proto-oncogenes do what to growth
Tumor Suppressors?
Stimulate
Supress
Gene whose activity is involved in turning a normal cell into a cancer cell
Oncogene
Oncovirus
Virus that causes cancer
Oncolytic viruses
Target and kill cancer cells
Cell culture or tissue culture are used to
Cultivate most animal viruses
Observable change in a cell in vitro caused by a viral action such as cell lysis
Cytopathic effect
Microscopiclly visible structure within a virally infected cell, representing the site at which the virus replicates
Inclusion body
The titer of the virus is the dilution at which 50% of the inoculated host are killed this is reported as
LD ⁵⁰ leathal dose or ID⁵⁰ infective dose
_____ occurs when individual viral particles attach to surface molecules of multiple RBC connecting cells to form an aggregate
Hemaggulutination
The highest dilution showing maximum aggulation is the ____ of the virus
Titer
Viruses that lyse their host cells can be assayed by….
Counting plaques
_____ are experimental methods for assessing the presence, localization, or biological activity of a substance in living cells and biological matrices.
Assays
______ cause productive infections, but the viral particles are continually extruded from the host in the assembly process, and the cells are not killed.
Filamentous phage
_____ results from a packaging error during the phage assembly. Particles can transfer any gene of a donor to recipient cell
Generalized transduction
____ results from an excision mistake made by a temperate phage during the transition from a lysogenic cycle to lytic cycle. Only genes located near the site at which the temperate phage integrates are transduced
Specialized transduction
_____ are used to quantitate the phage particles in a sample
Plaque assays
Entry and uncoating
In the case of animal viruses, the entire _____ enters the cell
Virion
Entry and uncoating
Enveloped viruses either fuse with the host membrane or are taken in via _____ the same method all Non-enveloped virions enter
Receptor mediated endocytosis
Do viruses use their own DNA polymerase or the host.
What is the advantage
Their own
They can replicate when the host cell isn’t
RNA viruses usually replicate in _____
The cytoplasm
General term for any virally encoded Enzyme that replicates the genome of an RNA virus
Replicase
___ is one of the most precise methods for determining the concentration of animal viruses in a sample
Plaque assay
____ is a measurement of the amount or concentration of a substance in a solution
Titer
_____ estimates the titer by determining the ID⁵⁰ or LD⁵⁰
Quantal assays
_______ do not bind to receptor site however through wound sites
Virions (viruses outside the host) of Viroids (plant disease)
Transmissible spongiform encephalopathy are?
caused by?
Fatal neurodegenerative disease that put sponge-like holes in the brain
Prions
_________ is defined as an experiment for estimating the potency of a drug, material or process by means of the reaction that follows its application to living matter.
Quantal assay
Viruses are classified generally based on…
Type of cell they infect. Pro/Eukaryotes
Bacteriophages attach via
Tail fibers
Integrated phage DNA is called
Prophage
This process called _____ allows phage to enter lytic cycle and escape the cell
Phage Induction
This process is an Excision mistake during transition from lysogenic to lytic cycle of temperate phage
Specialized transduction
______ are used to count phage particles in samples
Plaque assays
Zones of clearing from bacterial lysis are called…
Plaques
Counting plaques yields the ______ which is concentration of phage in the original sample
Titer
Replicase in the replication of RNA viruses generates mutations. This results in antigenic variation called…
Antigenic drift
Some RNA viruses have a segmented genome. When 2 viruses infect a host the 2 strains may “reassort” into 1 strain.
This process is called
Antigenic shift
Release
Most enveloped viruses leave cell via….
Non-enveloped viruses leave….
Budding
Apoptosis
Do phages infect humans
Nope
Capsid outside, DNA inside is this process
Eclipse
Phage encoded repressor does this
Prevents excision
Counting plaque yields ______ concentration of phage in original sample
Tither
Animal viruses penetration is called….
Bacterial virus penetration is called….
Uncoating
Eclipse
_______ is the accumulation of a series of minor genetic mutations.
While _______ involves “mixing” of genes from influenza viruses from different species
Antigenic drift
Antigenic shift
Plaque assay measures the virus ______ which is the concentration of viruses in a sample.
Tither
_____ process contains only bacterial DNA transfer and not viral DNA
Generalized transduction
Temperate phage infection in which the phage DNA replicates silently within the host cell as a prophage, instead of directing a productive infection
Lysogenic infection
_____ occurs if a prophage carries genes that change the phenotype of the host cell.
Lysogenic conversion
Acute infections are akin to ____ lytic infections
Productive
A type of persistent infection Latent infections are akin to _____in bacteriophages in that the virus genome remains in the host cell but is not active
Lysogeny
Many viruses can be detected by their effect on cells in a culture (how they change the cell), called _______
Cytopathic effect
