Exam 2 Viruses Flashcards
What does virus mean and who named it
pasteur named it
Means poison
What was the first virus discovered
The tobacco Mosaic virus in 1935
All viruses are considered obligate blank blank
Intracellular parasites
What are the two components that make up the structure of a virus
One type of nucleic acid either RNA or DNA but not both
Surrounded by a protein coat
What does the host range of a virus refer to?
The spectrum of hosts that the virus can infect
What does it mean to cross host range barriers?
The virus can cross to other species
What are bacteriophage also known as phages?
Viruses that can affect bacteria
Why must a bacteria interact with receptors?
What can receptors do?
In order for a virus to enter a cell, it must interact with receptors
However, receptors can change shape to accommodate the virus
What are oncolytic viruses
Viruses that attack tumors
What type of equipment determines a virus’s size?
An electron microscope and the size is typically 20 to 1,000 nanometers
What is a virion?
A complete fully developed infectious particle
It’s made of a capsule and nucleic acid
It’s considered a fully developed virus
What type of nucleic acid does a virus use?
Rna or DNA but not both
What type of nucleic acid often makes him more virulent virus
Rna
What is the shape of RNA versus DNA in a virus?
Rna is linear
DNA is circular
What is a capsid
The protein coat on the outside of a virus
What is a capsomere?
Subunits of the protein coat
Why is the capsid arrangement important
It is used to identify the virus
What is a virus envelope and how often do we see it
It is a covering over the capsid and some viruses have it but some do not
What is the composition of a virus in chemistry terms
Phospholipid bilayer proteins and a few carbs
What are the two ways of a virus being created by the host cell
Formed by the host cell membrane as the virus exits
Assembled by the host cell
How does The new copies of the virus leave the cell in the lytic cycle
They rupture through the cell membrane
How does the lysogenic cycle create new viruses?
The virus takes over the cell and the viral DNA or RNA tells the cell to make an outer coat for the new viruses
What do the spikes do on a virus
Allow it to attach to the cell membrane of the host cell
What is agglutination?
Clumping of the host cells via attachment to the spikes of a virus
How does a non-envelope virus attach to the host cell?
The capcid attaches to the host cell and injects in the DNA or RNA but not the capsid
What is the capsid?
The protein coat on the outside of the virus
Define morphology
The shape of something
What is the morphology of a helical capsid with example?
The capsid is a hollow of cylinder
Examples are Ebola and rabies
What is the morphology of a polyhedral capsid with example?
Icosahedron meaning 20 triangular faces and 12 corners
Example is polio
What is the morphology of an enveloped capsule with example?
It is usually spherical
If it is helical, an example would be influenza
If it is polyhedral, an example would be herpes
What is making the influenza virus worse?
Mutation
What is the name of the herpes virus
Hsv1
Herpes simplex virus 1 and herpes simplex virus 2
In the taxonomy of viruses, what is symptomatology?
Classifying viruses based on the type of disease they cause
What do we currently base our taxonomy of viruses on Three things
Nucleic acid type such as RNA or DNA
Replication means such as lytic or lysogenic
Morphology
What taxonomy terms do we use when classifying viruses
Order family genus species
What is considered a viral species?
Viruses that share the same genetic information and host range
What are viral plaques?
Dead bacteria killed by viruses.
Clear zones on a medium like a plate indicates area where virus has destroyed the bacteria
What is needed for a virus to be replicated or cultivated?
Living cells
What type of medium is a bacteriophage grown in?
A liquid medium or on a solid
What is a theoretical count of viruses
An educated guess. Every plaque represents one virus Particle
What is a plaque forming unit or PFU
How many plaque spots you have? It will report the theoretical count
What is commonly used for isolation, cultivation and identification of animal viruses initially
Then what did it change to?
Finally, what is used now for this purpose?
Mice rats and guinea pigs initially
It was changed to embryonated eggs
Currently cell cultures are used
How do you determine if a embryonated egg has a virus and how does a virus get in it?
You inject the virus into the eggs duck’s goose or chicken, eggs or common
Growth of the virus is signaled by death or damage to the fetus
How is a cell culture for a virus created?
A slice of tissue is exposed to enzymes which break the cells apart so they are separated
The cells are then suspended in the solution called a culture broth with nutrients to keep them alive
How do you tell normal cells versus
Cells infected with the virus in a cell culture
Normal cells adhere to the glass
Viral infection causes the layer to degenerate and tear off the glass
What are cytopathic effects?
Changes that occur from a viral infection
When was the first virus link to cancer
1908
What is a sarcoma
Cancer of connective tissue
What is a adenocarcinoma?
Cancer of glandular epithelium meaning the glands
What are three reasons why we may not think that viruses cause cancer?
Because they can lay latent
Because they have a long incubation time after infection
Because we think of cancer as not being contagious but viral diseases are
What are oncogenes in viruses?
Cancer inducing genes in viruses
What are mutagenic factors?
Factors that activate cancer-causing genes or oncogenes
What is an oncogenic virus capable of stimulating?
Tumor production
What percent of all cancers are caused by viruses as of right now?
10%
What is transformation with regards to viruses and cancer
Tumor cells develop traits distinct from uninfected cells
The virally infected cells develop new characteristics due to the viral infection and nothing else
What are two examples of transformation that can occur?
Different shapes
DNA abnormalities such as damage to the cell membrane
Define latent
Dormant
Define persistent or chronic
Something that develops slowly over a long period of time
How many and what type of diseases do prions cause?
Nine known diseases
All of them neurological
What does prion stand for?
Proteinaceous infectious particle
Why are plant viruses important and what are some of the signs?
They can hurt our economy
Some signs are they are discolored won’t grow or have stunted growth or wilting
What are plant viruses cultivated in And how are they altered to allow the viruses to grow?
Protoplasts And spheroplasts where the cell walls are partially or completely removed
What is a viroid and what type of living thing does it infect
It is a chain of RNA and it is only a plant pathogen
