Chap 13
How does the productive extrustion phage lifecycle differ from the productive lytic phage lifecycle? Be sure to include ALL differences in their lifecycles.
Extrusion phages do not make nuclease during the synthesis stage and therefore do not destroy host bacterial DNA. (1pt) The assembly and release steps occur at the same time. (1pt) Large amounts of lysozyme are not made during release (1pt.) The host cell is not killed and the phages squeeze out of the host one at a time. (1pt)
Specific fusion protein is used in enveloped animal viruses
Penetration and Uncoating
What are the components of viruses?
RNA or DNA, protein
bacteriophage
a virus that infects bacteria
what are the two major categories of viral infections?
acute and persistant
Which type of cell death do some viruses trigger as a means of being released?
apoptosis
New virions are constructed
assembly
Viral particles are constructed
assembly
Phage binds to bacterial surface proteins
attachment
Virus binds to glycoproteins on host cell
attachment
Viruses that infect bacteria are called
bacteriaophages- "phages"
The subunits of the protein covering of a virus
capsomere
Shingles is
caused by Varicella virus leaving nerve cells and infecting skin
enveloped viruses can derive their envelopes from
certain host organelles and the host cytoplasmic membrane
the hep B virus often causes an infection that results in a continuous and low level production of virus particles. This type of infection pattern is specifically described as a _________. infections?
chronic
What are classified as persistent infections?
chronic and latent
A type of animal virus infection where the infected person is contagious (infectious to others), regardless of whether or not they have symptoms
chronic infection
Which type(s) of nucleic acid are used by viruses as genetic material?
double stranded DNA single stranded DNA double stranded RNA single stranded RNA
ID the method by which non enveloped virus can gain entry into animal cells
endocytosis of the virus by the host cell
The two processes by which viruses penetrate host cells are _________ or ________________ with the host cell membrane.
endocytosis; fusion
A patient gets diarrhea after eating contaminated food. Which of the following routes of transmission does this represent?
enteric
A virus that is covered by a phospholipid bilayer
enveloped
Describe the structure of an enveloped complex shaped bacteriophage.
enveloped-has a double layer of lipid outside of the capsid-similar to a cell membrane complex-nucleocapsid, tail or sheath, and tail fibers**This structure is only found in phages (not in animal viruses.)
in a lysogenized bacterium, __________ of the prophage results in a lytic infection.
excision
A phage that does not kill its host cell as it exits is
extrusion
TorF lysogens are more susceptible to reinfection by the same type of phage.
false
ID all methods by which an enveloped virus can gain entry into animal cells
fusion of the viral envelope and the cell membrane endocytosis of the virus by the host cell
A small amount of lysozyme is used along with the tail in this step
genome entry
Genetic material enters the host cell
genome entry
Which viral shape is found in phages?
icosahedral
An animal virus infection that is characterized by having initial symptoms, then a long symptomless period followed by having symptoms again is known as a(n)
latent infection
what cycle ends with the death(lysis) of the bacterial host cell?
lytic
A swelling due to abnormal cell growth that is capable of spreading is known as
malignant
one of the early proteins expressed in the T4 lytic cycle is an enzyme called an ___________ that degrades the bacterial DNA.
nuclease
What refers specifically to both the protein covering of a virus and to the nucleic acid inside?
nucleocapsid
most animal DNA viruses will replicate within the host cell's _________.
nucleus
BC they are dependent on host cells, viruses are classified as which of the following?
obligate intracellular parasites
An open space (hole) in a monolayer of host cells. (This open space is present because one virus infected and killed one host cell.)
plaque
What makes viruses challenging to study?
-They can only be seen using an electron microscope -they are obligate intracellular parasites
List the steps of an animal virus infection cycle in the correct order
1-attachment 2-penetration and uncoating 3-synthesis of viral proteins and replications of the genome 4-assembly 5-release
A bacterium that has a piece of viral DNA inserted into its own bacterial chromosome. The virus in this scenario is known as: (Hint: I want the term that refers to the virus only!)
prophage
Genes that stimulate normal cell growth and division in animals are
proto-oncogenes
The three bacterial defense mechanisms against infection by phages are altering _________ sites, _________-modification systems. and ____________ systems.
receptor, restriction, CRISPR
Enveloped viruses use budding
release
Large amount of lysozyme produced
release
Virions leave the host cell
release
Viral genome is copied
replication
Viral transcription and translation occurs
replication
In a phage that has been latent for some time, what determines that the phage will now become lytic?
repressor on excisase is removed
HIV is described as an _________ bc it replicates the RNA genome by using reverse transcript to produce a DNA intermediate.
retrovirus
An enzyme that uses an RNA molecule as a template to make a complementary copy of DNA is called which of the following?
reverse transcriptase
Virus exits the host organism's body
shedding
Viron
single virus particle
Method that allows the DNA of some phages to be inserted in the host bacterial chromosome.
site specific recombination
Upon entry into a new host cell, what determines that the phage will become latent?
slow host cell metabolism
In __________ transduction, only bacterial genes adjacent to the prophage can be transferred; an in ____________ transduction any bacterial gene can be transferred.
specialized; generalized
Viral DNA is copied
synthesis
Viral transcription and translation occurs
synthesis
what are the viral components that attach to specific receptors on host cells?
tail fibers and spikes
What is the purpose of restriction enzymes in bacteria?
to prevent viral infection
Virus enters a new host organism's body
transmission
What term describes the process by which the viral nucleic acid is released from the protective protein coat?
uncoating
What term is used to refer to a single virus particle?
virion
A person is bitten by a rabid racoon and then develops rabies. This is an example of which route of transmission of animal viruses?
zoonoses