Viruses, Viroids, & Prions
In which phase of the T4 lytic cycle are new phage particles put together?
assembly
The process of ______________ occurs when viruses are taken into the cell through engulfment.
endocytosis
The mechanism of entry for an animal virus is primarily determined by whether or not the virus has a(n) ___________ (structure).
envelope
Which types of viruses are released by budding?
enveloped viruses
____________ transduction is the result of packaging errors during the assembly stage of phage replication.
generalized
Which of the following are cytopathic effects of viruses?
inclusion bodies & syncytia
Viruses that infect bacteria are called ____________.
phages
Circular clearings (holes) caused by phage-induced lysis in a bacterial lawn are called _________.
plaques
A(n) _________ is a proteinaceous infectious agent associated with transmissble spongiform encephalopathies.
prion
Which form of transduction results from excision errors during the transition from a lysogenic to lytic cycle?
specialized
Malignant
spreads to nearby tissue
Proto-oncogene
stimulates cell growth
Which of the following are viral protein components that attach to specific receptors on host cells?
tail fibers & spikes
A ___________ phage is a bacteriophage that incorporates its DNA into the host genome as a prophage.
temperate
________ ___________ is the most common method of cultivating animal viruses.
tissure culture
Which term describes the process by which the viral nucleic acid is released from the protective protein coat?
uncoating
A(n) _______ microscopic agent composed of nucleic acid surrounded by a protein coat.
virus
_________ are infections agents that infect only bacterial cells.
Phages
_________ is a name given to a disease-causing agent composed only of protein.
Prion
_________ are non-cellular, infectious agents composed of only a single-stranded RNA molecule.
Viroids
The 2 major categories of viral infections are:
acute & persistent
ID50 is the amount of pathogen required to
infect half of a test population
Tumor suppressor gene
inhibits cell growth
LD50 is the amount of pathogen required to
kill half of a test population
A viral infection in which the viral genome is integrated into a host cell chromosome is categorized as a(n) _________ infection.
latent
A(n) __________ infection is characterized by the incorpation of phage DNA into the host.
lysogenic
A change in the phenotype of a lysogen as a consequence of genetic material carried by a prophage is called
lysogenic conversion
The ___________ cycle ends with the death (lysis) of the bacterial host cell.
lytic
Which term is used to describe the protein layer that is sandwiched between the capsid & envelop in enveloped virus?
matrix
At minimum, all viruses are composed of:
nucleic acids & proteins (capsid)
Because they are dependent on host cells, viruses are classified as ___________ intracellular parasites.
obligate
Phages infect which of the following cells?
only bacterial cells
Plant viruses initially gain entry to host cells by:
passing through wounds in the host cell wall
The concentration fo infectious phage particles in a sample is called the _________.
titer
__________ results from a bacteriophage transferring DNA from 1 bacterium to another.
Transduction
List the steps of an animal virus infection cycle.
-Attachment -Penetration & uncoating -Synthesis of viral proteins & replication of the genome -Assembly -Release
Which of the following are types of bacteriophages?
-lytic phage -filamentous phage -temperate phages
Which of the follwoing methods can be used to quantify animal viruses?
-plaque assay -direct count -quantal assay -hemagglutination
Which of the following occur during the synthesis stage of the T4 lytic cycle?
-synthesis of phage proteins -Degradation of bacterial DNA -Synthesis of phage DNA
Which of the following occurs during the synthesis stage of the T4 lytic cycle?
-synthesis of phage proteins -degradation of bacterial DNA -synthesis of phage DNA
Rank from smalles to largest.
1. Viruses 2. Bacteria 3. Human cells
A single virion could contain a genome of:
DNA or RNA
In whcih ways do newly assembled viruses leave their host cell?
budding & apoptosis
Benign
does not spread to nearby tissue
The 2 methods for cultivating animal viruses are:
embryonated chicken eggs & tissue culture
Animal viruses that do not have an envelope can only enter their host cell by ____________.
endocytosis
