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