Chapter 6: Introduction to Viruses and Prions Flashcards
(31 cards)
All viruses have a general structure called?
Capsid
What is a capsid?
Protein coats that enclose and protects their nuclei acid
The capsid together with the nucleic acid is called?
Nucleocapsid
Some viruses have an external covering that is made up of phospholipid bilateral and its called?
Envelope
Viruses lacking an envelope are called?
Naked
What are the two distinct capsid types?
- Helical
2. Icosahedral
When are viral envelope acquired?
When the virus leaves the host cell- taken from the host cell membrane.
What are spikes?
Exposed proteins on the outside of the envelope
Function of spikes
Essential for attachment of the virus to the host
Are spikes considered a virulence factor?
Yes, because viruses such as H1N1 can attach to the lower respiratory tract and cause pneumonia
Function of the Capsid
Protects the nucleic acid when the virus is outside of the host cell
Function of envelope
Helps virus bind to a cell surface and assist in penetration of the viral DNA or RNA into suitable host cells
An example of a complex virus (atypical viruses)
Poxviruses lack a typical capsid and are covered by a layer of lipoprotein
What are lipoproteins?
Surface proteins that you can find in gram (-) bacteria
What type of virus has a polyhedral nucleocapsid along with a helical tail and attachment fibers?
Bacteriophages
The viral genome consist of?
- DNA or RNA, but NEVER both.
- Genes necessary to invade host cell and redirect cell activity to make new viruses.
Steps of viral replication
Adsorption Penetration Uncoating Synthesis Assembly Release
Adsorption
Binding of virus to specific molecules on the host cells
Penetration
Genome enters the host cell
Uncoating
The viral nucleic acid is released from the capsid
Synthesis
Viral components are produced
Assembly
New viral particles are constructed
Release
Assembled viruses are released by budding (exocytosis) or cell lysis
Penetration of the virus can occur through?
Endocytosis and fusion
