Chapter 13 Exam 2
lysozyme, phage, 200
In the final stage, release, ____ digests the cell wall and releases _______ in a burst size (T4=)
degrades the host cells DNA host cells RNA polymerase
In the third stage, synthesis early proteins are 1. a nuclease that _____ and 2. proteins that modify ____
PrPc
cells produce normal form of prions
lysogenic conversion
change in the phenotype of a lysogen as a consequence of genetic material being carried by a prophage
type of nucleic acid, shape of virus, host infected and strandedness of nucleic acid
classification of viruses can be based on all of the following
nucleocapsid
complete complex of nucleic acid and protein packaged in the virion
viron
complete virus in its inert non-replicating form; also referred to as a viral particle
chronic infection
continuous, low-level production of new virus particles by animal host cells aka a person can transmit the virus to others in the absence of symptoms ex. Hep B
DNA, RNA or reverse transcribing viruses
in animal virus replication, there are 3 strategies for replication, what are they?
pores
in the fourth step of the filamentous phage cycle what do the other proteins form?
lysogen
infected host cell
PrPsc
infectious prion proteins
envelope
lipid layer
viral, chromosome
lysogeny is integration of the ____ genome into the host _____
hijack host
main goal of early proteins
plaque assay
method to determine the number of viral particles in a suspension using a monolayer of tissue culture cells, clear zones around uninfected cells are counted
naked virus
nucleocapsid that lacks envelope and is more resistant to disinfectants
endocytosis
plasma membrane surround the virion, forming a vesicle and the vesicle then releases
neural, neurons
prion proteins accumulate in _______ tissue: causing ____ to die
proteinaceous, protein
prions are _____ infectious agents composed solely of ___
apoptosis
programmed cell death, triggered by naked viruses
so it will not recognize its own promoters
purpose of the early protein that modifies the host cells RNA
transmissable spongiform encephalopathies
refer to all prion diseases because of their spongelike appearance of brain tissue
fusion
virus fuses with plasma membrane, naked viruses cannot use this process for entry
nucleocapsid, envelope, host attachment
enveloped viruses are a _____ enclosed in a ____ in a lipid layer with spikes that help with ______
1. template for mRNA 2. copies of genome
in the filamentous phage cycle, what are the complementary DNA strands used for
pores, coat, nucleocapsids
last step of the filamentous phage cycle involves phage DNA being excreted through ______, proteins ______ the DNA and form _________
prophage
latent form (integrated but doesnt cause disruption) of a temperate phage whose DNA has been inserted into the host's DNA
prions
linked to slow fatal human/animal diseases
partial immunity
lysogen is immune to superinfection; infection by same phage or similar
endocytosis
naked virus must use ____ to enter an animal cell because they have no lipid envelope and therefore cannot fuse to host membranes
nucleocapsid, disinfectants
naked viruses are a _____ only and are more resistant to ____
enveloped virus
nucleocapsid that has envelope
virus
obligate intracellular parasites, infectious agents but not alive
bacteriophages
only ___ trigger cell lysis by the production of a phage-encoded lysozyme
chronic, latent
persistent infections can either be ____or _____
prophage
phage DNA that is latently incorporated into the bacterial host genome
lytic phage
phage exits host and host is lysed (dies); a productive infection
capsid
protein coat that determines that determines the shape of a virus
infectious prion
resistant to proteases; become insoluble, aggregate; usually resistant to heat, chemical treatment
filamentous phage
single-stranded DNA phages that cause productive infections but the host cells are not killed by lysis (grow more slowly)
1. attachment 2. genome entry 3. synthesis of proteins and genome 4. assembly 5. release
stages of lytic phage
1. attachment 2. penetration and uncoating 3. synthesis 4. assembly 5. release
steps of animal virus replication
size
viruses are NOT classified according to?
nuclease to digest the host DNA protein that modifies host RNA polymerase
what are the early viral proteins produced in the T4 lytic cycle?
1. T4 capsomers 2. T4 tail fibers
what are the late viral proteins produced in the T4 lytic cycle?
1. acute 2. persistant
what are the two categories of animal virus infections?
integrate their genomes into the host genome
what can temperate (lysogenic) phages do that lytic phages cannot?
lytic infection
what does excision of a repressor protein in the lysogenic state result in?
inaccurate excision
what mistake in temperate phage replication cycle leads to specialized transduction?
packaging error of phage incorporating fragments of host DNA
what mistake leads to generalized transduction?
1. attachment 2. assembly 3. genome entry 4. release 5. biosynthesis of viral components
what steps do both temperate and lytic phages have?
tail fibers, bacterial receptors, cell wall
In the first stage (lytic) attachment, phage ___ ____ bind to ___ _____ on _____ ______ ex. T4
maturation, protein scaffolds
In the fourth stage, assembly or ____ some components spontaneously assembly while others require ___
fusion or endocytosis
In the penetration and uncoating step of an animal virus, what are the two ways of entry?
lysozyme, tail, genome
In the second stage (lytic), genome entry, phage enzyme ____ degrades the cell wall, ___ contracts to inject the _____
structural, capsid and tail
In the third stage (lytic), synthesis of late proteins that are ____ ; make up the ___ and ___ are synthesized
proteins, genome
In the third stage (lytic), synthesis of phage _____ and ______
replicates
a temperate phage takes the lysogenic path: the prophage now ______ with host chromosome
lyse, phages
a temperate phage takes the lytic path: lastly, the cells _____ , releasing new_______
lambda, attaches
a temperate phage takes the lytic path: phage _____ first ______ to a bacterium
linear, circularizes
a temperate phage takes the lytic path: second, the phage injects _____ phage DNA, it ______ and enter lytic cycle
replicates, synthesizes
a temperate phage takes the lytic path: third, the phage DNA ______ and ______ phage-encoded proteins
tumor
abnormal cell growth
partial immunity and lysogenic conversion
advantaged of temperate phage (2)
uncoating
after a virus enters the host cell, the nucleic acid separates from its protein coat
latent infection
after initial infection the viral genome can remain silent as a provirus (cannot be eliminated) and be reactivated later ex. cold sores
1. have their nucleic acid enter the host cell 2. have their nucleic acid replicate in the host cell
all phages must have the ability to do what two things?
phage induction
allows phage to escape damaged host
lysogenic infection
an infection that results in the integration of bateriopahge DNA into the chromosome of a bacterial host, no new particles are made
nucleus
animal DNA viruses replicate within the host cell's ____
surface proteins
antigenic drift occurs when mutations accumulate encoding for ___ ___ that can be recognized by the immune system; can result in a person being susceptible to a new variant arising later
segmented, reassortment
antigenic shift results when a ____ virus undergoes ____
lysogeny
bacteria that has prophage integrated into its chromosome
preventing phage attachment
bacterial defense in which bacteria can alter or cover its surface receptors to prevent infection ex. S. aureus makes protein A to cover phage receptors
viral oncogenes
can interfere with host control mechanisms and stimulate cell growth and tumor inducing
1. either DNA or RNA 2. linear, circular or fragmented 3. double or single-stranded
3 characteristics of a nucleic acid
1. icosahedral 2. helical 3. complex
3 shapes of viruses
1. lytic phage 2. temperate phage 3. filamentous phage
3 types of bacteriophages due to host relationship
DNA: DNA polymerase RNA: replicase RT: reverse transcriptase
DNA, RNA and RT, replicase or transcriptase?
HIV, reverse transcriptase
___ is described as a retrovirus because it replicates its RNA genome by using ____ ____ to produce a DNA intermediate
helical, icosahedral
___ viruses have capsomers arranged to form long cylinders, while capsomers of _____ viruses are arranged as a multifaceted, polygonal capsid
proto-oncogenes, tumor suppressor
___-____ and ____ ___ genes work together to stimulate or inhibit growth and cell division of a tumor
PrPsc, PrPc
_____ converts ______ folding to PrPsc
Creutzfeldt-Jakob disease, Bovine spongiform encephalopathy
______ and _________ are examples of prion-related diseases
repressor protein
_______ ________ maintain lysogenic state of the temperate phage
integrase
______directs the incorporation of phage DNA into a bacterial chromosome
temperate
a _____ phage is a bacteriophage that incorporates its DNA into the host genome as a prophage
protease
a phage-encoded enzyme that destroys repressor protein; allows prophage to be excised
DNA, chromosome, latent
a temperate phage takes the lysogenic path: after attaching and injecting phage DNA that circularizes, the phage______ integrates into host ________ by site specific recombination. The cell remains _______.
M13
filamentous phage (extrusion) uses ______ phage as a model
protein, F pili
first step of the filamentous phage cycle involves attachment to ______ on __ ______ of bacteria (E. Coli)
coat, cytoplasmic membrane
fourth step of the filamentous phage cycle involves m13 phage ______ protein molecule inserted into host __________ ____________
protease
how can a repressor protein be excised?
budding
how do most animal viruses release?
capsomers
identical subunits that compose capsids and determine the shape of a virus
type of genome of virus
in animal virus replication, there are 3 strategies for replication based on what?
RNA, DNA
reverse transcriptase uses a ____ molecule to make a complementary strand of _____
single stranded, cytoplasm
second step of the filamentous phage cycle involves _______ _________ DNA genome entering the _________
lytic, lysogenic, lambda
temperate phages can either be ____ or ____ and model phage is:
polymerase, complementary
third step of the filamentous phage cycle involves DNA ________ (of host) synthesizes _________ DNA strands for M13
plaque assays
used to quantitate phage particles in samples
spikes
viral glycoproteins that stick out from the viral envelope and attach to host cell receptors in an animal virus