In what year did Stanley Prusiner discover prions?
Which disease did Stanley Prusiner first identify as being caused by prions?
How are prions different from all other known infectious agents?
They lack nucleic acid
How does specialized transduction differ from regular lysogeny?
The prophage in specialized transduction carries with it pieces of the host chromosomal DNA
What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?
The host DNA integrates, with the prophage, into the new recipient chromosome.
How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population?
The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.
How do naked viruses differ from enveloped viruses in their attachment/penetration phase?
Their nucleic acids are injected into the cell.
Which virus employs the use of an RNA-dependent RNA polymerase?
+RNA & -RNA & dsRNA viruses
Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?
Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane?
In viral replication, what can be used directly as messenger RNA?
What structure found of some viruses can be used for identification?
We sometimes are able to generate antibodies (immune system proteins) that bind to and cover up some of the proteins on the outermost portion of a virus while it is in the bloodstream. This renders the virus unable to reproduce. Which step of viral replication are antibodies directly preventing?
Enveloped viruses have a layer of lipids surrounding their capsid. This envelope is made mostly of host cell membrane. In which step does the virus acquire this envelope?
During budding release, the virus "steals" some of the host membrane to use for itself.
What occurs during viral uncoating?
capsid breaks apart releasing viral gemone
How are viruses different from cells?
They require a host in order to reproduce.
What is the function of the structural elements of a virus?
To package and protect the viral genome
Cause plant diseases
short pieces of naked RNA (no capsid)
300-400 nucleotides long
no protein coat
The normal function of the PrP protein in mammals is believed to be:
assisting in normal synaptic development and function.
How do normal prion proteins (PrP) differ from the infectious prion proteins?
Normal PrP have alpha-helices; infectious PrP have beta-pleated sheets.
How does the number of infectious prions increase?
Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion.
Why are the beta-pleated multimers of PrP potentially pathogenic?
They are more stable as multimers and resistant to proteases.
Which of the following statements regarding latent viral infections is true?
Latent infections can persist for years in an individual without causing any symptoms.
What culture line is widely used for culturing viruses that require a human host?
Diploid cell culture lines, developed from human embryos
What determines the host range for a virus?
The presence or absence of particular components on the surface of a host cell that are required for the virus to attach.
What was the first disease associated with a virus & in what year?
Tobacco mosaic disease, 1892
What was the first human disease associated with a virus?
Taxonomy of viruses
family names end in -viridae
genus names end in -virus
group of viruses sharing the same genetic information & host
Phage DNA incorporated in host DNA
During viral infection, random pieces of bacterial DNA are accidentally packaged into viral capsid. Any part of the host chromosome can be transferred to a recipient cell
a part of the host genome becomes incorporated into the virus before it lyses from the host- bacterial genes can spread this way
special DNA phages that undergo absorption and penetration but are not replicated or released immediately (inactive prophage stage)
when a bacterium acquires a new trait from its temperate phage
when a phage modifies the phenotype of a host cell or integrates new genes into the bacterial chromosome
- Papillomavirus: human wart virus
- Orthopoxvirus: smallpox & cowpox
- Simplexvirus (HSV1 & HSV2)
- Varicella zoster virus (chicken pox & shingles)
- Orthohepadnavirus: Hepatitis B
ssRNA sense +strand
- Enterovirus: poliovirus
- Rhinovirus: common cold
ssRNA (2 strands)
Use reverse transcriptase (RT) to produce DNA from viral genome
- Lentivirus (HIV)
ssRNA antisense -strand
multiple RNA strands
Proteinaceous infectious particle
only destroyed by incineration of autoclaving (high heat & high pressure)
Want to see the other 44 Flashcards in Topic 6?JOIN TODAY FOR FREE!