Exam 1 - Ch. 13 - Characterizing and Classifying Prions Flashcards
What causes the diseases that plague most of the industrial world?
Viruses
What are some of the characteristics of viruses?
Miniscule, acellular, it either has DNA or RNA but never both.
What does acellular mean?
No processes of life
A virus in its extracellular state is called what?
A virion
What does a virion look like?
Protein coat surrounding a nucleic acid core.
What is the protein coat of a virion called?
capsid
What is the outer structure of phospholipids that encloses the nucleocapsids of some viruses called?
envelope
What does the capsid and/or envelope do for the virion?
Provides protection for the viral nucleic acid and means of attachment to host’s cells
What happens to the virus once it is inside the host cell?
The capsid is removed and it simply exists as a nucleic acid.
What is it called when the virus removes its capsid?
uncoating
Viruses can be _____ or _____.
Specific or generalists
Most viruses are ____.
Specific, only attack particular host cells
What types of organisms are susceptible to a viral attack?
All types
What are the 3 viral shapes?
Complex
Helical
polyhedral
What viral shape is capsid of many shapes?
complex
What type of virus shape is spiral?
helical
What type of viral shape is a geodesic dome?
polyhedral
What is the most common viral shape?
polyhedral
What virus is famous for it’s bullet shaped capsid?
Rabies
What shape is the bacteriophage?
complex
3 Functions of the viral envelope.
Provides protection
Plays a role in host recognition.
Helps viruses enter hosts cells.
A virus that has an envelope is called?
Enveloped virion
A virus with no envelope is called?
Non-enveloped/naked virion
The projections of viral glycoproteins on the envelope are called?
spikes
Where does the viral envelope come from?
Acquired from host cell during viral replication or release.
4 ways viruses are classified?
Type of nucleic acid,
Presence of an envelope,
Shape,
size
How are viruses named?
name of disease + virus
What is special about viral replication?
They are dependent of hosts’ organelles and enzymes to produce new virion.
What viral replication cycle results in death and lysis of host cell?
Lytic replication
What are the five stages of Lytic replication of a virus.
Attachment of virus to host. Entry into host. Synthesis of new nucleic acids. Assembly of new virions. Release of new virions.
Modified viral replication cycle where infected host cells grow and reproduce normally for generations before the lyse.
Lysogeny
What are temperate phage?
Inactive “hanging out - house guest”
What are prophages?
Inactive phages.
When phages carry genes that alter phenotype of a bacterium, it is called? (viral chromosome incorporates into host’s cell.)
lysogenic conversion.
Viral replication of animal viruses is same as basic replication as bacteriophages but there are some differences. (3)
Presence of envelope around some (a lot have).
Eukaryotic nature of animal cells.
Lack of cell wall in animal cells.
Attachment of animal viruses is by what?
Chemical attraction
Animal viruses do not have tails or tail fibers like bacteriophages, but the doe have what that helps them attach to host?
Glycoprotein spikes or other attachment molecules.
3 mechanisms of entry of animal viruses?
Direct penetration
Membrane fusion
endocytosis
Which mechanism of entry is the easiest?
Direct penetration
What happens that is different in membrane fusion of virus?
Viral glycoprotein remain in cytoplasmic membrane.
What is different about the process of budding in enveloped viruses?
It doesn’t kill the cell.
What is the process of budding in Enveloped viruses?
Virus obtains capsid and picks up glycoprotein on cell surface and buds of leaving host cell.
When animal viruses remain dormant in host cells it is called?
Latent viruses or proviruses
Is incorporation of previous into host DNA permanent?
YES
What is the most common and inexpensive way to culture viruses in the laboratory?
In embryonated chicken eggs.
What are other ways to culture viruses in lab?
In mature organisms (like bacteria, plants, and animals) and in cell (tissue) culture- cells isolated and grown on medium with a broth.
What are proteinaceous infectious agents that lack a nucleic acid called?
prions
Are prions easy to destroy?
No, they are very, very difficult to destroy!
What are the ways to destroy prions?
Incineration and autoclaving in sodium hydroxide
How does a prion cause disease?
Prion PrP converts cellular PrP into Prion PrP by inducing conformation change.
What is the disease-causing form of Prion Pro?
B-Sheets (beta)
What is normal form of cellular PrP?
a-helices (alpha)
Where is the prion disease expression most predominant?
In the nervous system.
What is the characteristic of the brain with a prion disease?
Large vacuoles form in brain - characteristic spongy appearance.
What are 3 prion diseases that cause spongiform encephalopathies?
BSE - mad cow’s disease
vCJD - humans get from eating cows with disease
Kuru
