Chapter 13: Viruses - Shape, naming, and multiplication of animal viruses Flashcards
1
Q
What is the polyhedral shape of viruses? (2)`
A
- usually icosahedral
- shape with 20 triangular faces
2
Q
What is the helical shape? (2)
A
- long rods
- can be rigid or flexible
3
Q
What is the shape of an enveloped virus? (2)
A
- roughly spherical
- dictated by lipid bilayer
4
Q
What is the complex shape of viruses? (2)
A
- polyhedral head with a helical tail
- only found in bacteriophages
5
Q
In lecture, what is the most common entity in the world?
A
bacteriophages
6
Q
What are 3 factors that classify viruses?
A
- Nucleic acid type (DNA or RNA, single or double strand, segmented or single)
- capsid structure
- presence of envelope (none = naked)
7
Q
How does capsid structure help classify viruses?
A
they can either be polyhedral or helical
8
Q
How do we name viruses?
A
- Family - ends with suffix - viridae
- genus - ends with suffix - virus
- species - specific epithets are not used
9
Q
What are 6 ways that animal viruses multiply? (6)
A
- Adsorption
- Penetration
- Uncoating
- Biosynthesis
- Maturation and assembly
- release
10
Q
What is adsorption? (2)
A
- attachment to host cell
- viruses have attachment sites that recognize protein or glycoprotein of host
11
Q
What is penetration? (3)
A
- entry into host cell
- Most enveloped viruses enter by fusion
- naked virus enters the cell via endocytosis
12
Q
Since fusion occurs in penetration, what does it mean?
A
- lipids of envelope fuse with host cytoplasmic membrane
13
Q
What occurs in uncoating?
A
- viral nucleic acid is freed from the capsid
14
Q
What occurs in biosynthesis? (4)
A
- viral nucleic acids are replicated
- DNA replicated -> nucleus
- RNA replicated -> cytoplasm
- viral proteins (capsomeres) are synthesized in the cytoplasm
15
Q
What does biosynthesis rely on?
A
- host metabolic machinery
ex. replication and transcription enzymes, ribosomes
