2. Viruses, Viroids, Prions Flashcards
1
Q
Viruses can only replicate when?
A
- Viruses can replicate only inside host cells
(obligate intracellular parasites) - host cells supply the building blocks (nucleic acids, amino acids), the machinery (ribosomes) and the energy required to produce new virus particles.
2
Q
What are virions?
A
viruses exists as inert infectious particles outside of the host
3
Q
What is Capsid?
Capsomeres?
A
- a protein coat that enclosing the nucleic acid inside
- protein subunit that makes up the capsid. it determines the shape of the virus
4
Q
What is Nucleocapsid?
A
nucleic acid+ protein coat
5
Q
What is the Envelope?
Proteins in the envelope are…?
A
- lipid-containing layer with embedded proteins;
- Proteins in the envelope are virus specific and are enclosed on the viral genome.
- in animal viruses, this envelope originates from the cytoplasmic membrane of the host cells
6
Q
Compare Helical virus,
Polyhedral virus,
Complex virus
A
- Helical virus: rod shape, typical of many plant viruses
e. g. tobacco mosaic virus - Polyhedral virus: polyhedron
e. g. Human papilloma virus - Complex virus
e. g. bacteriophages.
7
Q
What are Viroids?
How do they cause diseases?
A
- closed circles of single-stranded RNA containing 240-380 nucleotides.
- Replication is dependent on host machinery, viroids overtakes the host machinery, causing disease.
8
Q
What are Prions?
A
- Prions consist ONLY one protein.
- Cause neurological degenerative disorders:
9
Q
What are Misfolded prion proteins?
A
The misfolded prion proteins (PrPSc) induces misfolding of the PrPC protein. The prion protein does not replicate, it induces accumulation of misfolded PrPSc proteins, which kills the cell. The PrPC protein is primarily found in neurons.
